WO2012020617A1 - Magnetic material, magnetic shaped object, and rotating machine - Google Patents
Magnetic material, magnetic shaped object, and rotating machine Download PDFInfo
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- WO2012020617A1 WO2012020617A1 PCT/JP2011/065675 JP2011065675W WO2012020617A1 WO 2012020617 A1 WO2012020617 A1 WO 2012020617A1 JP 2011065675 W JP2011065675 W JP 2011065675W WO 2012020617 A1 WO2012020617 A1 WO 2012020617A1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/047—Alloys characterised by their composition
- H01F1/053—Alloys characterised by their composition containing rare earth metals
- H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
- H01F1/0555—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together
- H01F1/0558—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together bonded together
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/047—Alloys characterised by their composition
- H01F1/053—Alloys characterised by their composition containing rare earth metals
- H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
- H01F1/058—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IVa elements, e.g. Gd2Fe14C
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/047—Alloys characterised by their composition
- H01F1/053—Alloys characterised by their composition containing rare earth metals
- H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
- H01F1/059—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and Va elements, e.g. Sm2Fe17N2
Definitions
- the present invention relates to a structure and composition with high magnetic properties as a permanent magnet of a 4f transition element-3d transition element alloy.
- the index as a high-performance permanent magnet material includes three elements of Curie temperature, magnetization, and magnetic anisotropy.
- a method of inserting atoms into a parent phase crystal is known.
- N nitrogen
- Sm 2 Fe 17 the magnetic properties of the parent phase are improved.
- R 2 Fe 17 R is a 4f transition element
- Nd 2 Fe 14 B which has the highest performance as the parent phase of the permanent magnet material, still has a large amount of rare earth element used (Nd element with respect to Fe element is 14.3% in terms of element composition ratio). It is important to improve the magnetic properties in a composition having a smaller amount of rare earth element than this.
- Sm 2 Fe 17 N 3 described in Patent Document 1 has improved magnetic properties as compared with the parent phase, it still has a small magnetic moment and magnetic anisotropy.
- Gd 2 Fe 17 F 3 described in Non-Patent Document 1 makes a calculation prediction regarding an increase in magnetic moment and an increase in magnetic anisotropy energy, it does not discuss the stability of the crystal structure, but actually It is unclear whether it exists as a stable system. There is no mention of the Curie temperature.
- Non-Patent Document 2 Since R 2 Fe 17 F x described in Non-Patent Document 2 has not been subjected to elemental analysis of the F element, it is unclear whether the increase in the Curie temperature is due to the effect of F atoms, and the Curie temperature The maximum rise is as low as about 40 ° C.
- An object of the present invention is to provide a magnet material that is more excellent in magnetic properties such as magnetic moment and magnetic anisotropy than conventional magnet materials.
- the magnetic properties of the alloy are improved by arranging F atoms and N, H, or C atoms at the intrusion positions in the crystal lattice of the alloy. I found out that I can do it.
- the present invention includes the following configurations.
- the magnet material of the present invention includes a binary alloy represented by the chemical formula R—Fe (wherein R is a 4f transition element or Y), or a chemical formula R—Fe—T (wherein R is T is a 3d transition element excluding Fe, or Al, Si, Ga, Mo, Nb or W. However, when T is W, R is a 4f transition element other than W or Y. )), Which contains F atoms and N, H, or C atoms at the intrusion position in the crystal lattice.
- the heat treatment temperature dependence of TC and the heat treatment temperature dependence of (c) coercive force H c and (d) reversal magnetic field distribution SFD of the entire sample at liquid nitrogen temperature and room temperature are shown.
- the correlation between the Curie temperature increase rate ⁇ T C / T C and the expansion rate ⁇ v / v of the unit cell volume in Sm 2 Fe 17 H ⁇ F x is shown.
- Ammonium fluoride shows a 300 ° C.
- FIG. 6 is a (001) plane view schematically showing displacement of Fe atoms when F atoms enter a hexagonal crystal lattice. It is a (003) plane view schematically showing the displacement of Fe atoms when F atoms enter the hexagonal crystal lattice.
- the 3d transition metal group having relatively strong itinerary is described by the Hubbard model, and in the 4f rare earth metal group having strong localization, the Anderson model is often used.
- the electronic state and magnetic structure are determined by the competition between the gain of kinetic energy reduction due to the spatial spread of electrons and the increase of Coulomb energy due to the proximity of electrons.
- the electronic state and magnetic structure are determined by further considering the interaction between conduction electrons and localized electrons in the Hubbard model.
- the principles of the present invention generally relate to Kanamori conditions derived from a single Hubbard model of 3d transition metals. The Kanamori condition is obtained by removing the overestimation of Coulomb energy with respect to the Stoner condition.
- U is the Coulomb energy
- G (0,0) is a parameter between two electrons having a wave vector of 0 and is about the reciprocal of the 3d bandwidth
- D (E F ) is the electron density of states at the Fermi level.
- the Kanamori condition indicates that in order for ferromagnetism to occur, the bandwidth needs to be quite large, and at the same time the state density of the Fermi level must be locally increased. Since the electronic state density increases with the increase of the crystal lattice, the electronic state density changes due to the volume change of the unit cell. Therefore, when a volume change is introduced into the unit cell by forced or spontaneous force, it is expected that a large change in magnetism occurs due to a change in the density of states in the vicinity of the Fermi level.
- the Bethe-Slater (or Neel-Slater) curve showing the interatomic distance dependence of the magnitude of the exchange interaction in 3d transition metal alloys shows that itinerant electron magnetic interactions oscillate with interatomic distance It is a curve.
- ⁇ -Fe hereinafter simply referred to as Fe
- Co and Ni have a wide interatomic distance. It is known that too. This is because in Fe, the itinerant nature of electrons is too strong and there are few localized electrons, so the exchange interaction is small, and in Co and Ni, the localization is too strong and the overlap of wave functions is small, so the exchange interaction is small. Means.
- F atoms and other nonmagnetic atoms penetrate into the alloy of the 4f transition element-Fe element of the parent phase, so that near the Fermi level of Fe. A decrease in the density of states and an increase in the localization of Fe occur, causing the effects of increased magnetization and increased Curie temperature. Furthermore, the penetration of atoms including F atoms and the strong electronegativity of F atoms cause an improvement in magnetic anisotropy.
- the magnetic characteristics of the parent phase can be obtained by introducing nonmagnetic atoms including F atoms. Improve dramatically.
- the N atom has the chemical formula R 2 (Fe, T) 17 N x (0 ⁇ x ⁇ 3), the chemical formula R 3 (Fe, T) 29 N y (0 ⁇ y ⁇ 4), the chemical formula R ( It is known to arrange as Fe, T) 12 N z (0 ⁇ z ⁇ 1), and F atoms are arranged in the same manner as N atoms.
- the introduced amount of nonmagnetic atoms is too large, the Fe band width becomes too narrow due to too strong localization, so that the Kanamori condition is not satisfied and the ferromagnetism is weakened.
- the magnetization due to nonmagnetic atoms including F atoms and the Curie temperature increase and increase notably only in a crystal structure having a site where the distance between Fe atoms is short.
- the value at which the positive / negative exchange interaction between Fe atoms is switched is about 0.245 nm (the distance between Fe atoms at which the exchange interaction is maximized is about 0.260 nm).
- the effect of increasing ferromagnetism by introducing F atoms is remarkable.
- ammonium fluoride (NH 4 F), acidic ammonium fluoride (NH 4 F ⁇ HF), ammonium silicofluoride ((NH 4 F) 2 SiF 6 ), ammonium borofluoride (NH 4 BF 4 ) and other methods using gas generated by pyrolysis and sublimation, and nitrogen trifluoride (NF 3 ), boron trifluoride (BF 3 ), sulfur hexafluoride (SF 6 ) hydrogen fluoride, There is a method using a gas such as fluorine. Depending on the reactivity of each gas, they can be mixed or used simultaneously.
- a ferromagnetic fluorine compound magnet having the following characteristics is synthesized by performing fluorination heat treatment at a temperature lower than 400 ° C., preferably lower than 350 ° C. by sublimation of NH 4 F with respect to Sm 2 Fe 17. Succeeded in doing.
- the principle of the present invention mainly depends on the above-described characteristics of Fe, and when a nonmagnetic atom including an F atom enters, a geometrical effect is generated as the crystal lattice volume increases, and a magnetic moment is large. There is an increase and an increase in Curie temperature.
- the increase in magnetization and the increase in the Curie temperature are also caused by the effect of Fe localization due to the strong electronegativity of fluorine atoms. Since there is a difference in the spatial size of the intrusion position depending on the type of 4f transition element, the increase rate of magnetization and the Curie temperature increase rate are different depending on the type of 4f transition element.
- the present invention is a binary system of the chemical formula R—Fe (wherein R is a 4f transition element or Y) in which an F atom and an N atom, H atom or C atom are arranged at the intrusion position in the crystal lattice.
- R-Fe-T (wherein R is as defined above, T is a 3d transition element excluding Fe, or Al, Si, Ga, Mo, Nb or W, provided that T is W
- R is a 4f transition element other than W or Y.
- a magnet material including a ternary alloy wherein R is a 4f transition element or Y.
- a magnetic material comprising an alloy wherein R is a lanthanoid, particularly preferably a magnetic material comprising an alloy wherein R is Sm, Er, Tm, Pr, Nd, Tb or Dy, most preferably R is Sm or Nd.
- the present invention relates to a magnet material containing an alloy.
- the present invention preferably relates to a magnet material containing an alloy in which T is a 3d transition element excluding Fe, and particularly preferably relates to a magnet material containing an alloy in which T is Ti.
- the magnetic properties can be improved by arranging F atoms and N, H, or C atoms at the intrusion position in the crystal lattice of the alloy.
- F-Atom and H-Atom Containing Alloy As one embodiment of the present invention, a binary system of the chemical formula R—Fe in which F atoms and H atoms are arranged at the intrusion positions in the crystal lattice, or a chemical formula R—Fe—T 3 Examples thereof include a magnet material containing a base alloy.
- a method for introducing F atoms and H atoms into the intrusion position in the crystal lattice for example, ammonium fluoride (NH 4 F), ammonium acid fluoride (NH 4 F ⁇ HF), ammonium silicofluoride ((NH 4 F) 2 SiF 6 ), ammonium borofluoride (NH 4 BF 4 ) and the like, and a method of simultaneously performing hydrogenation and fluorination by heat treatment using hydrogen fluoride gas generated by thermal decomposition and sublimation. It is also possible to carry out the already known hydrogenation method and fluorination method separately. In that case, it is desirable to carry out hydrogenation in advance, since subsequent fluorination easily occurs. However, since hydrogen atoms and fluorine atoms only need to coexist at an intrusion position in the crystal lattice with an appropriate occupation ratio, they may be hydrogenated after fluorination.
- the alloy used in the present invention preferably uses the chemical formula R 2 (Fe, T) 17 , the chemical formula R 3 (Fe, T) 29 , and the chemical formula R (Fe, T) 12 phase. These alloys are distinguished on the basis of the CaCu 5 structure by their three-dimensional stacking method.
- the present invention is applicable to all phases having a crystal structure based on the CaCu 5 structure. Therefore, the present invention can be applied to the chemical formula RT 5 , chemical formula RT 7 phase, and more complex multi-component systems.
- the upper limit of ⁇ + x, ⁇ + y, and ⁇ + z is limited by the number of intrusion positions.
- the composition of the alloy in the present invention is determined by an electron probe microanalyzer (EPMA) and a time-of-flight secondary ion mass spectrometer (TOF-SIMS).
- R is Pr, Nd, Tb or Dy, and 0.5 ⁇ z (that is, 0 ⁇ ⁇ 0.5, 0.5 ⁇ z ⁇ 1, and 0.5 ⁇ In the case of ⁇ + z ⁇ 1), the alloy has uniaxial magnetic anisotropy.
- the alloy containing F atoms and H atoms is at least one of rare earth fluoride, rare earth oxyfluoride, iron, and iron fluoride depending on the temperature of the heat treatment for introducing F atoms and H atoms. including.
- a binary alloy of the chemical formula R—Fe in which an F atom and an N atom are arranged at an intrusion position in a crystal lattice, or a chemical formula R—Fe—T A magnetic material containing a ternary alloy of Arranging F atoms and N atoms makes it possible to increase the Curie temperature, increase the magnetic moment, and improve the magnetic anisotropy.
- the upper limit of ⁇ + x, ⁇ + y, and ⁇ + z is limited by the number of intrusion positions.
- the composition of the alloy in the present invention is determined by EPMA, TOF-SIMS.
- R is Pr, Nd, Tb, or Dy, and 0.5 ⁇ ⁇ + z (that is, 0 ⁇ ⁇ 1, 0 ⁇ z ⁇ 1, and 0.5 ⁇ ⁇ + z ⁇ 1)
- the alloy has uniaxial magnetic anisotropy.
- the method for introducing the F atom and the N atom is not particularly limited.
- a method of heat-treating the alloy in the presence of nitrogen trifluoride can be mentioned.
- the alloy in the present invention contains at least one of rare earth nitride, rare earth fluoride, rare earth oxyfluoride, iron, and iron fluoride depending on the heat treatment temperature.
- F- and C-atom-containing alloys As one embodiment of the present invention, a binary system of chemical formula R—Fe in which F atoms and C atoms are arranged at penetration positions in the crystal lattice, or 3 of chemical formula R—Fe—T Examples thereof include a magnet material containing a base alloy. Arranging F atoms and C atoms makes it possible to improve the thermal stability of the crystal lattice, increase the Curie temperature, increase the magnetic moment, and improve the magnetic anisotropy.
- the upper limit of ⁇ + x, ⁇ + y, and ⁇ + z is limited by the number of intrusion positions.
- the composition of the alloy in the present invention is determined by EPMA, TOF-SIMS.
- R is Pr, Nd, Tb or Dy, and 0.5 ⁇ ⁇ + z (that is, 0 ⁇ ⁇ 1, and 0 ⁇ z ⁇ 1, and 0.5 ⁇ ⁇ + z ⁇ 1)
- the alloy has uniaxial magnetic anisotropy.
- the method for introducing the F atom and the C atom is not particularly limited.
- a method of heat-treating the alloy using a hydrocarbon gas and a fluorine gas, or using a fluorocarbon can be mentioned.
- the F atom and C atom containing alloy contains at least one of rare earth fluoride, rare earth oxyfluoride, iron, and iron fluoride depending on the heat treatment temperature.
- Magnetic powder preparation Preparation of parent phase alloy: R and Fe are mixed and dissolved in a vacuum or in an inert gas or a reducing gas atmosphere to homogenize the composition (dissolution casting method). The obtained R—Fe based master alloy is coarsely pulverized in an inert gas using a ball mill.
- a reduction diffusion method in which samarium oxide powder and iron powder are mixed with granular metallic calcium and heated in an inert gas atmosphere can be used. Since the diffusion distance of Sm 2 Fe 17 is not higher than the peritectic temperature and the iron powder particle size is selected, the diffusion distance of Sm can be controlled to some extent.
- the casting method does not require indispensable uniform heat treatment. Since the Sm 2 Fe 17 alloy is obtained directly as a powder, a coarse pulverization step is not necessary. Further, in order to obtain a raw material powder having a smaller particle size, a microcrystalline oxide can be obtained by precipitating a hydroxide from a sulfuric acid aqueous solution of Sm and Fe and firing in the air. Magnetic powder having a particle size of several ⁇ m that does not require fine pulverization can be produced.
- ultra-quenched ribbon powder having a grain size of several ⁇ m to several tens of ⁇ m composed of a polycrystal having a crystal grain size of several tens to several hundreds of nm is required.
- the ribbon powder is obtained by a liquid superquenching method in which a molten mother alloy is jetted and cooled in an inert gas or reducing gas atmosphere such as argon gas on the surface of a rotating roll such as a single roll or a twin roll.
- a hydrogenation, decomposition, dehydrogenation, and recombination (HDR) method is also useful.
- a parent phase alloy can be produced by a nanoparticle process or a thin film process.
- the vapor phase method includes a thermal CVD method, a plasma CVD method, a molecular beam epitaxy method, a sputtering method, an EB vapor deposition method, a reactive vapor deposition method, a laser ablation method, a resistance heating vapor deposition method and the like.
- the liquid phase method includes coprecipitation method, microwave heating method, micelle method, reverse micelle method, hydrothermal synthesis method, sol-gel method and the like.
- the mother alloy or mother alloy powder obtained by the above method needs to be coarsely pulverized as necessary.
- the HDDR method is also effective, and forming a fine structure by this method is effective in coercive force expression.
- the coercive force is also exhibited by pulverization after the hydrogen fluoride gas treatment.
- Fluorination treatment, hydrogenation treatment, nitrogenation treatment, and carbonization treatment As a method for introducing a fluorine atom and a hydrogen atom, a nitrogen atom, or a carbon atom, there are methods as described in Examples 1 to 3 below, and all are solid-gas reactions by gas. In the solid-gas reaction process, in order to obtain a uniform composition, it is important to uniformly contact the surface of the powder with the gas. In particular, since a problem occurs when a large amount of powder is gas-treated, it is preferable to constantly flow and agitate the powder using a fluidized bed or the like. In addition, since the element intrusion reaction is diffusion-controlled, a powder having a uniform concentration distribution can be obtained more quickly as the particle size of the powder is smaller. However, if the particle size is too small, a stable flow becomes impossible, so there is a limit naturally, and a particle size of 10 ⁇ m to several 100 ⁇ m is appropriate.
- the coarse powder obtained in the element intrusion step is preferably finely pulverized to a mean particle size of 2 to 3 ⁇ m by a jet mill or a ball mill. In principle, it is desirable to pulverize to a single domain critical particle size of about 0.3 ⁇ m. Since the particle size after pulverization is very fine, it may be necessary to inactivate the particle surface by various methods.
- the magnetic powder for nanocomposites and HDDR magnetic powder exhibit coercive force without being finely pulverized, but the particle size may be affected when molded as a magnet body, and fine pulverization may be necessary.
- the particle size of the magnetic particles is related to the coercive force, adjusting the particle size distribution by fine pulverization and classification also leads to adjustment of the coercive force distribution, in the sense of increasing the performance and reliability of the magnetic particles. It is important.
- a magnet molded product including a magnet material and a binder is exemplified.
- Binder examples of the binder for hardening the magnetic powder include an inorganic binder and an organic binder.
- a low melting point metal or a resin can be used.
- the resin includes a thermosetting resin and a thermoplastic resin.
- EP (epoxy) resin can be used as the thermosetting resin
- PA polyamide, nylon
- PPS polyphenylene sulfide
- NBR acrylonitrile butadiene rubber
- CPE chlorinated
- Polyethylene polyethylene
- EVA ethylene vinyl acetate
- SiO 2 precursor CH 3 O— (Si (CH 3 O) 2 —O) m —CH 3 (m is 3 to 5, average is 4)
- water Dehydrated methyl alcohol and dibutyltin dilaurate can be mixed, impregnated and solidified.
- the problem is the orientation of the magnetic powder. It is important to orient the crystal axes of the particles in the desired direction during molding and to increase the density as in the case of an isotropic magnet.
- the magnetization reversal mechanism is roughly divided into a nucleation type and a pinning type. In the former case, the smaller the crystal grain size, the better the coercive force. In the latter case, the coercive force is determined by the shape and number of pinning sites.
- the magnet material of the present invention is expected to have both magnetization reversal mechanisms depending on the production method. It is considered that the coercive force is mainly determined by the nucleation type in the case of a crystal structure of several ⁇ m obtained by rapid cooling, and by the pinning type in the case of a crystal structure of several tens to several hundreds of nm obtained by liquid superquenching.
- the direction of the magnetic powder during molding is important for increasing the coercive force.
- the orientation of the magnetic powder by applying a magnetic field is added.
- the degree of orientation varies depending on the type of resin used, and it is important that each magnetic powder can move freely overcoming the viscosity of the binder when a magnetic field is applied.
- Injection molding is characterized by the ability to form complex shapes without post-processing.
- PA resin or PPS resin is used as the binder.
- a ferromagnetic fluorine compound bond magnetic powder as a raw material and a PA resin or PPS resin are kneaded together with an additive with a kneader to form a compound in a pellet form.
- This compound is put into an injection molding machine, heated and melted in a cylinder, and then injected into a mold for molding. It is necessary to adjust the viscosity of the resin.
- anisotropic magnetic powder the magnetic powder can be oriented by forming a magnetic circuit necessary for the mold. In order to produce a high-performance anisotropic injection-molded magnet, it is necessary to sufficiently orient the molten compound when it is injected into the mold.
- Rotating machine includes a rotating machine having a rotor containing a magnet material.
- the PC peripheral device include a spindle motor (for HDD, CD-ROM / DVD, and FDD) and a stepping motor (CD-ROM / DVD pickup, FDD head drive).
- the OA include a facsimile, a copy, a scanner, and a printer.
- the automobile include a fuel pump, an airbag sensor, an ABS sensor, an instrument, a position control motor, and an ignition device.
- PC game machines equipped with HDDs and DVDs, and TV set boxes that are devices that download and use digital data from the Internet or cable TV.
- home appliances include mobile phones, digital cameras, video cameras, MP3 players, PDAs, stereos, and the like.
- Other examples include air conditioners, vacuum cleaners, and power tools.
- the magnet material of the present invention has a large magnetovolume effect, a Villari effect is expected in which the strength of magnetization changes when a pressure is applied to the magnetic material. It belongs to the magnetostriction phenomenon in a broad sense and can be used industrially for sensors and actuators.
- Chlorination also includes a method of chlorination along with hydrogenation, nitrogenation, carbonization or fluorination.
- a feature of the present invention is that the magnetic modification occurs due to the geometric effect accompanying the increase of the crystal lattice volume due to the penetration of F atoms. Therefore, the same effect can be expected even with Cl atoms belonging to the same group instead of F atoms.
- the chlorination reaction can be carried out in the same manner as described in Examples 1 to 3 below.
- ammonium chloride (NH 4 Cl, decomposed at 338 ° C.) thermal decomposition product, nitrogen trichloride, boron trichloride, hydrogen chloride, chlorine or the like is used as the chloride gas.
- these may be mixed and used simultaneously.
- chlorination using ammonium chloride is preferably carried out at 300 ° C. or higher, particularly preferably at a decomposition temperature of 338 ° C. or higher. This does not apply when using nitrogen trichloride, boron trichloride, hydrogen chloride, or chlorine other than ammonium chloride.
- the method for introducing these elements is not particularly limited.
- Example 1 Alloy containing F and H atoms
- the R (Sm or Nd) -Fe main phase alloy takes into account the evaporation of rare earths and mixes Fe with Sm or Nd more frequently than the stoichiometric ratio. Then, it was dissolved in a vacuum, an inert gas or a reducing gas atmosphere to make the composition uniform. It was prepared by quenching after heat treatment for phase formation. Since Sm 2 Fe 17 , Sm 3 Fe 28 Ti, and NdFe 11 Ti are precipitated by the peritectic reaction of Fe, it is difficult to avoid a trace amount of ⁇ -Fe in the obtained alloy.
- the obtained ingot of Sm 2 Fe 17 was pulverized using a jet mill in an inert gas so that the average particle diameter was 10 ⁇ m or less.
- Ammonium fluoride (NH 4 F, solubility in water 45.3 mg / 100 ml (25 ° C.)) and Sm 2 Fe 17 , Sm 3 Fe 28 Ti and NdFe 11 Ti magnetic powders prepared by jet milling
- Hydrogen fluoride gas treatment was carried out using hydrogen fluoride gas generated by thermal decomposition and sublimation of acidic ammonium fluoride (NH 4 F ⁇ HF, solubility in water 77.7 g / 100 ml (25 ° C.)).
- Hydrogen fluoride gas treatment was performed in a gas flow format using a tubular furnace. In order to absorb the generated surplus gas, a trap mechanism was provided downstream of the reactor. The sample was spread thinly on a glassy carbon (GC) boat. However, the material of the sample container may be platinum or nickel other than carbon. A GC boat containing ammonium fluoride powder was disposed upstream and downstream. The amount of ammonium fluoride charged depends on the size of the reaction space, the gas flow rate, the heat treatment temperature, and the heat treatment time.
- a quartz tube having a radius of 28 mm and a length of 1200 mm was used, and 10 g of ammonium fluoride and ammonium acid fluoride were arranged upstream and 10 g respectively downstream of the magnetic powder 20 g.
- Ar was flowed at 200 ml / min. To heat the electric furnace. Heat treatment was performed at 150 ° C., 200 ° C., 250 ° C., and 300 ° C. so that the reaction time was 24 hours.
- the low temperature side where the decomposition / oxidation reaction of Sm 2 Fe 17 is relatively small is selected, and the temperature is preferably lower than 300 ° C.
- the temperature is preferably lower than 300 ° C.
- sufficient diffusion can be expected even in a short time because hydrogenation and fluorination proceed simultaneously.
- it greatly depends on the magnetic powder size, the crystal grain size, the surface state of the magnetic powder, the structure shape, and the like. It is expected that hydrogen fluoride and fluorination will be accelerated by mixing ammonium fluoride and acidic ammonium fluoride and magnetic powder and placing them on the GC boat, but the hydrogen fluoride generation source and magnetic powder are in direct contact with each other.
- vacuum replacement may be performed at the end of the heat treatment for the purpose of removing unreacted products.
- the sample was stored in a vacuum container in a polyethylene container because unreacted material may be attached.
- glass bottles may be used if the amount of unreacted material does not matter.
- FIG. 1 shows (a) Sm 2 Fe 17 magnetic powder, (b) 150 ° C. 24 h heat treated magnetic powder, (c) 200 ° C. 24 h heat treated magnetic powder, (d) 250 ° C. 24 h heat treated magnetic powder, (e) 300 ° C. 24 h heat treated magnetic powder, (F) The powder X-ray diffraction pattern at room temperature of the heat-treated magnetic powder at 350 ° C. for 24 hours is shown. In order to observe the structural change of the product due to the difference in heat treatment temperature, powder X-ray diffraction was performed.
- the diffraction peaks are SmFe 3 for ⁇ , Fe for ⁇ , FeF 2 (rutile type, space group P4 2 / mnm) ⁇ , SmF 3 ( ⁇ -YF 3 type, space group Pnma) and SmOF (strained CaF 2 type, space).
- Group R-3m is indicated by ⁇
- Sm 2 Fe 17 is indicated by no mark.
- SmOF samarium oxyfluoride is represented by SmOF because phases of various composition ratios and structures are known, and their diffraction peaks are located in diffuse diffraction and are difficult to distinguish.
- FIG. 2 shows (a) secondary electron image, (b) C, (c) N, (d) in a crystal grain cross section of 250 ° C. 24 h heat treated magnetic powder measured by an electron probe micro analyzer (EPMA). Element concentration distribution images of O, (e) F, (f) Fe, (g) Pr, and (h) Sm are shown, respectively. However, the element concentration is expressed in weight percentage (wt%).
- EPMA electron probe micro analyzer
- the F concentration tends to be high in the region where the O concentration is high. It is estimated that the outer periphery of the magnetic powder is easily oxidized, and the oxidized phase is fluorinated by heat treatment to produce SmF 3 , SmOF and the like. Further, it has been observed that the O concentration in the outer periphery of the magnetic powder is higher in the 250 ° C. 24 h heat treated magnetic powder than in the Sm 2 Fe 17 magnetic powder, and oxidation is considered to occur mainly during the heat treatment. The effect of moisture adhering to the magnetic powder surface is suggested.
- FIG. 3 shows a place A, a place B, and a place C (measured using spectral crystals (a) LS7A (diffraction grating), (b) RAP (rubidium acid phthalate), and (c) LS5A (diffraction grating).
- energy spectrum near FK alpha in FIGS. 2 (a) see secondary electron image), and elemental quantitative results are shown, respectively.
- the unit of the horizontal axis is converted from wavelength to energy and displayed.
- the elemental ratio at any location Sm has a Fe ⁇ 2:17, also, F atom location A, and Detection was not possible at location B, and 17 at% was detected at location C.
- the electron beam beam diameter is 1 ⁇ m
- the penetration of the electron beam into the metal material, and the escape depth of the characteristic X-ray is about 2 ⁇ m to 3 ⁇ m
- Sm 2 Fe 17 is decomposed at the place C
- FeF 2 , SmF 3 , SmOF, etc. are presumed to be mixed.
- a temperature-programmed desorption gas analysis was performed to infer invading elements from the analysis of the element species generated from the entire sample.
- FIG. 4 shows the temperature dependence of the desorption gas of (a) Sm 2 Fe 17 magnetic powder and (b) 250 ° C. 24 h heat-treated magnetic powder, respectively.
- the Curie temperature of the purchased Sm 2 Fe 17 magnetic powder is about 4 ° C. to 12 ° C. higher than the literature value, and supports the presence of H atoms contained in a trace amount.
- TOF-SIMS time-of-flight secondary ion mass spectrometer
- FIG. 5 shows (a) total ions, (b) Fe + , (c) FeH + , (d) FeOH + , (e) Sm + , (f) SmF + , and 250 ° C. for 24 h.
- G Ion images of H + , (h) Na + , (i) Al + , (j) Si + , and (k) Ca + are shown, respectively. From the ion images of (b) Fe + and (e) Sm + , it was observed that the Fe element and the Sm element showed a non-uniform composition distribution.
- FIG. 6 shows (a) total ions, (b) FeO ⁇ , (c) FeO 2 ⁇ , (d) FeO 2 H ⁇ , (250 ° C. for 24 h heat treated magnetic powder measured using TOF-SIMS.
- e The ion images of H ⁇ , (f) C ⁇ , (g) O ⁇ , (h) OH ⁇ , (i) F ⁇ , (j) CN ⁇ , and (k) Cl ⁇ are shown, respectively.
- There is a correlation between the ion images of (e) H ⁇ and (g) O ⁇ and the O concentration tends to increase corresponding to the H concentration.
- the first is to separate the heterogeneous phase of the synthesized magnetic powder with a ball mill or jet mill, etc., and to separate it according to the structure and composition by methods such as magnetic attraction and centrifugation, and then the weight and chemical composition of the target phase before and after treatment. It depends on the analysis method.
- Second using TOF-SIMS and elemental determination in the target phase.
- the third is the identification of F atom position and occupancy by wide-angle X-ray absorption fine structure (EXAFS) measurement and X-ray / neutron Rietveld analysis.
- EXAFS wide-angle X-ray absorption fine structure
- X-ray / neutron Rietveld analysis since it is a magnetic material, it can also be identified from magnetic measurements. By combining the above methods, it is possible to identify with higher accuracy.
- FIG. 7 shows the temperature dependence of the magnetization of Sm 2 Fe 17 magnetic powder heat-treated at various temperatures in a 0.5T magnetic field.
- the magnetization of Sm 2 Fe 17 magnetic powder is a temperature change of a standard ferromagnet according to mean field theory. However, an increase in magnetization at 200 ° C. or higher means that Fe is generated by phase decomposition by a trace amount of oxygen contained in dilute He as a measurement atmosphere.
- the Curie temperature is 120 ° C. from the polarization point. It was observed that the Curie temperature increased according to the heat treatment temperature and reached a maximum of 260 (140 ° C. increase) in the heat treated magnetic powder at 200 ° C. for 24 hours. In the case of heat treated magnetic powder at 200 ° C.
- the magnetization jump in this temperature region is a change in magnetic anisotropy related to the localization of Fe. It is a magnetic transition having a scale as an evaluation criterion of atom penetration other than the Curie temperature. That is, it has a certain correlation with the expansion rate of the crystal lattice.
- Sm 2 Fe 17 is completely phase-decomposed into Fe, SmF 3 , SmOF, etc., and what is observed is the temperature change of Fe. If the temperature dependence of the magnetization is significantly different from the Brillouin function in this thermomagnetic property evaluation, it is suggested that multiple phases contribute to the temperature dependence of the magnetization. Provides a measure of whether the diffusion is uniform.
- FIG. 8 shows (a) crystal lattice constant expansion rate ⁇ a / a axis, ⁇ c / c axis, and unit cell volume expansion rate ⁇ v / v, and (b) Curie temperature increase in Sm 2 Fe 17 H x F y .
- the dependence of the rate ⁇ T C / T C on the heat treatment temperature is shown.
- SFD switching field distribution
- the standard for the expansion rate and the rate of increase is Sm 2 Fe 17 magnetic powder.
- SFD is a dimensionless quantity derived by dividing the half width of the peak obtained by differential analysis of the magnetic field dependence of magnetization by the coercive force. This amount gives a measure of the distribution of the magnetization reversal field of the permanent magnet material. In the case of the low coercive force as in this case, the smaller the value, the harder the magnetic material, and the larger the value, the softer the magnetic.
- ⁇ a / a of the crystal lattice constant takes a maximum value when the heat treatment temperature is 200 ° C. and gradually decreases with heat treatment at a higher temperature.
- the c-axis expansion ratio ⁇ c / c of the crystal lattice constant takes a minimum value when the heat treatment temperature is 200 ° C. and gradually increases with heat treatment at a higher temperature. This is presumed that atoms invaded by heat treatment at 200 ° C. for 24 hours are desorbed by heat treatment at a higher temperature.
- the Curie temperature rise rate also exhibits the same behavior as the a-axis expansion rate ⁇ a / a and the unit cell volume expansion rate ⁇ v / v of the crystal lattice constant, and the maximum value when the heat treatment temperature is 200 ° C. However, it was observed that the temperature decreased gradually with heat treatment at higher temperatures.
- FIG. 9 shows the correlation between the Curie temperature increase rate ⁇ T C / T C and the unit cell volume expansion rate ⁇ v / v in Sm 2 Fe 17 fluorinated with HF.
- the unit cell volume is a value at room temperature.
- the origin was forcibly passed to reduce the approximation error (increase the R factor).
- ammonium silicofluoride (NH 4 F) 2 SiF 6 ) and ammonium borofluoride (NH 4 BF 4 ) are used to react. The degree of was adjusted.
- the expansion rate of the unit cell volume is correlated with the amount of penetration of H atoms and F atoms.
- the slope of Sm 2 Fe 17 H x F y tends to be larger than that of Sm 2 Fe 17 H x C y N z. is there.
- This difference in magnetovolume effect may reflect the degree of localization of Fe atoms due to the strong electronegativity of F atoms.
- the above correlation is also observed in principle in the chemical formula R 2 (Fe, T) 17 F x , the chemical formula R 3 (Fe, T) 29 F y , and the chemical formula R (Fe, T) 12 F z . It is expected.
- the coercive force is slight, but it is estimated that a significant coercive force is exhibited by grinding from about 2 ⁇ m to about 3 ⁇ m.
- the particle size is 1 ⁇ m or more.
- FIG. 10 shows the magnetic field dependence of magnetization before and after pulverization of Sm 3 Fe 28 Ti heat-treated with ammonium fluoride and ammonium acid fluoride at 300 ° C. for 1 h.
- the pulverization was performed by wet pulverization in a cyclohexane solvent using a ball mill. After removing the solvent, it was aligned with stearic acid and measured. However, secondary agglomeration of magnetic powder is caused by ball milling and the degree of magnetic powder orientation is lowered, and saturation magnetization is evaluated to be low due to contamination with impurities. Sufficient dispersion and crushing treatment and removal of impurities are necessary.
- the magnetic anisotropy changes from in-plane anisotropy to uniaxial anisotropy, and has the potential as a permanent magnet material. This is because the 4f electron orbit responsible for the magnetism of Sm has a cigar shape, and the same effect is expected for Er and Tm.
- the crystal field acting on the rare earth element is considered, in the chemical formula R 2 (Fe, T) 17 H ⁇ F x (1 ⁇ x), the chemical formula R 3 (Fe, T) 29 H ⁇ F y (2 ⁇ y)
- the rare earth element R is Sm, Er, or Tm, uniaxial magnetic anisotropy is obtained.
- the rare earth element R is Pr, Nd, Tb, Dy in the chemical formula R (Fe, T) 12 H ⁇ F z (0.5 ⁇ z)
- the uniaxial magnetic anisotropy is obtained.
- the above-described method can be used. Uniaxial magnetic anisotropy can be evaluated by orientation and fixation in a magnetic field, and it is desirable to evaluate a single-phase sample that has been pulverized, crushed and separated in order to increase accuracy.
- FIG. 11 shows the heat treatment temperature dependence of hydrogenation and fluorination of the liquid nitrogen temperature and the magnetic anisotropy energy of Sm 3 Fe 28 Ti at room temperature.
- a sample oriented using a stearic acid (melting point 68 ° C. to 71 ° C.) in a 2T magnetic field was evaluated in the vertical direction and the parallel direction, and the enclosed area was derived as the magnetic anisotropy energy.
- the measuring device can only apply a magnetic field up to ⁇ 6T, the intersection of both curves was calculated by extrapolation using the saturation asymptotic rule, and the enclosed area was derived. Therefore, there are some errors.
- Uniaxial magnetic anisotropy can also be analyzed using micromagnetic evaluation means such as ferromagnetic resonance, Mossbauer, neutrons, and nuclear magnetic resonance.
- Example 2 F atom and N atom containing alloy
- Sm 2 Fe 17 it has been intensively studied and clarified that fluorine atoms are discharged out of the crystal lattice at a temperature higher than 300 ° C. and nitrogen atoms are taken into the crystal lattice from around 300 ° C. Therefore, it is difficult to carry out nitrogenation and fluorination at the same time, and it is necessary to carry out nitrogenation first in view of the stability of the system.
- the R (Sm or Nd) —Fe-based main phase alloy was produced in the same manner as in Example 1. Of course, it is not limited by the manufacturing method of the alloy. Nitrogenation and fluorination used nitrogen trifluoride (NF 3 , purity 99.99% or more) gas. As the reaction apparatus, a Ni reaction vessel having a sufficient wall thickness was used. In addition, Ni-based alloys such as Inconel and Monel can be used. Stainless steel was used for the sample container. In advance, a sample container was placed in the reaction container, and nitrogen trifluoride was introduced at a temperature higher than the working temperature, and a passivation process was performed for a sufficient time.
- Nitrogenation and fluorination used nitrogen trifluoride (NF 3 , purity 99.99% or more) gas.
- NF 3 nitrogen trifluoride
- Stainless steel was used for the sample container. In advance, a sample container was placed in the reaction container, and nitrogen trifluoride was introduced at a temperature higher than the working temperature, and
- Nitrogen trifluoride was introduced and held for 1 hour, furnace cooled to a temperature T 2 for fluorination, and held for 4 hours.
- the selection of the processing temperatures T 1 and T 2 and the selection of each holding time dominate the penetration rate occupancy and the atomic diffusion.
- the position where the fluorine atom penetrates disappears and the fluorination does not occur. Therefore, appropriate adjustment is necessary.
- sufficient exhaust treatment was performed, and the furnace was cooled in an Ar atmosphere and released to the atmosphere at 40 ° C. or lower.
- Table 1 shows the Curie temperature of Sm 2 Fe 17 heat-treated at each temperature. Thus, it was found that the Curie temperature differs depending on the difference in heat treatment temperature. Since the difference in the heat treatment temperature causes a difference in the degree of nitridation and fluorination, it indicates that the Curie temperature rises by nitridation and fluorination. By fluorination, the Curie temperature of Sm 2 Fe 17 N 3 exceeds 470 ° C.
- FIG. 13 shows powder X-ray diffraction patterns of Sm 2 Fe 17 , Sm 2 Fe 17 N 3 , and Sm 2 Fe 17 N ⁇ F x .
- N atoms and F atoms were detected from the region presumed to be the parent phase at the center of the crystal grains. It is unavoidable to avoid some decomposition and generation of Sm and Fe due to non-uniformity of the Sm 2 Fe 17 phase during nitrogenization and fluorination, and the outer periphery of the magnetic powder after fluorination has SmN, SmF 3 , SmOF, Fe, FeN, FeF 2 and FeF 3 were present.
- rare earth nitride rare earth fluoride, rare earth oxyfluoride, iron, and iron fluoride is included when nitriding and fluorinating rare earth iron It will be.
- O atoms are caused by moisture adhering to the outer periphery of the magnetic powder and oxidation during heat treatment, and are unavoidably mixed. Desirably, it is an atom to be excluded.
- N atoms and F atoms penetrate and diffuse from the outer periphery of the crystal grains, so that N and F atoms inevitably have a concentration gradient from the grain boundary toward the parent phase center. Will have. Since the diffusion rate of F atoms is slower than that of N atoms, the concentration non-uniformity tends to be large in F atoms.
- Sm 2 Fe 17 N ⁇ F x can be synthesized by heat-treating Sm 2 Fe 17 in a nitrogen trifluoride atmosphere, and an increase in the Curie temperature was confirmed. Besides increasing the Curie temperature, we observed an increase in magnetic moment and an improvement in magnetic anisotropy. Separately conducted with regard Sm 3 Fe 28 Ti, and NdFe 11 Ti, it was observed almost the same tendency.
- the measured magnetic powder had an average particle size of 10 ⁇ m, the coercive force was slight, but it is estimated that a significant coercive force is exhibited by grinding from about 2 ⁇ m to about 3 ⁇ m. In principle, it is desirable to pulverize to a single domain critical particle size (about 0.3 ⁇ m). However, since problems in process such as oxidation occur, it is desirable that the particle size is 1 ⁇ m or more.
- the magnetic anisotropy changes from in-plane anisotropy to uniaxial anisotropy, and has the potential as a permanent magnet material.
- the rare earth element R is Pr, Nd, Tb, Dy in the chemical formula R (Fe, T) 12 N ⁇ F z (0.5 ⁇ ⁇ + z)
- the uniaxial magnetic anisotropy is obtained.
- Uniaxial magnetic anisotropy can be evaluated by the method described in Example 1. In order to experimentally obtain the values of ⁇ , ⁇ , ⁇ , x, y, and z of the prepared sample, the analysis method described in Example 1 can be used.
- Example 3 F-atom and C-atom-containing alloy
- Sm 2 Fe 17 it has been intensively studied and clarified that fluorine atoms are discharged out of the crystal lattice at a temperature higher than 300 ° C., and carbon atoms are taken into the crystal lattice from around 300 ° C. Therefore, it is difficult to carry out carbonization and fluorination at the same time, and it is necessary to carry out carbonization first in view of the stability of the system. Moreover, since carbonization increases the thermal stability of the crystal lattice more than nitrogenation, it is desirable to carry out carbonization first.
- the R (Sm or Nd) —Fe-based main phase alloy was produced in the same manner as in Example 1. Of course, it is not limited by the manufacturing method of the alloy.
- butane C 4 H 10 , purity 99.5% or more
- fluorine F 2 , purity 99.5% or more
- Carried out A sample 5 g was thinly spread and placed in a stainless steel container (5 cm ⁇ 7 cm). The operation of evacuation (0.4 kPa) and Ar (purity 99.9995% or more) replacement was performed three times. After raising the temperature to 120 ° C. in dilute Ar, vacuuming and Ar replacement were performed again for the purpose of removing moisture.
- T 1 is preferably 300 ° C. or higher
- T 2 is preferably 300 ° C. or lower. In this example, T 1 was selected to be 350 ° C., and T 2 was selected to be 250 ° C. After holding, sufficient exhaust treatment was performed, and the furnace was cooled in an Ar atmosphere and released to the atmosphere at 40 ° C. or lower.
- Sm 2 Fe 17 C ⁇ F x can be synthesized by heat-treating Sm 2 Fe 17 using butane and fluorine gas, and an increase in the Curie temperature was confirmed. Besides increasing the Curie temperature, we observed an increase in magnetic moment and an improvement in magnetic anisotropy. Separately conducted with regard Sm 3 Fe 28 Ti, and NdFe 11 Ti, it was observed almost the same tendency.
- the measured magnetic powder had an average particle size of 10 ⁇ m, the coercive force was slight, but it is estimated that a significant coercive force is exhibited by grinding from about 2 ⁇ m to about 3 ⁇ m. In principle, it is desirable to pulverize to a single domain critical particle size (about 0.3 ⁇ m). However, since problems in process such as oxidation occur, it is desirable that the particle size is 1 ⁇ m or more.
- the magnetic anisotropy changes from in-plane anisotropy to uniaxial anisotropy, and has the potential as a permanent magnet material.
- Uniaxial magnetic anisotropy can be evaluated by the method described in Example 1.
- ⁇ , ⁇ In order to experimentally obtain the values of ⁇ , x, y, and z, the analysis method described in Example 1 can be used.
- Example 4 Magnetic powder production (1) Formation of parent phase alloy: In this example, magnetic powder obtained by pulverizing an SmFe-based ribbon obtained by quenching a mother alloy with a composition adjusted was used as the magnetic powder of the 4f transition element-3d transition element of the parent phase.
- the SmFe-based master alloy was mixed with Sm and Fe and dissolved in a vacuum or in an inert gas or reducing gas atmosphere to make the composition uniform (dissolution casting method).
- the obtained master alloy was coarsely pulverized in an inert gas using a ball mill so that the average particle diameter was about 10 ⁇ m.
- Example 5 Chlorination Magnetic powder produced in Example 1 was used as magnetic powder. That is, magnetic powders of Sm 2 Fe 17 , Sm 3 Fe 28 Ti, and NdFe 11 Ti produced by jet mill grinding were used.
- the hydrogen chloride gas treatment was carried out in a gas flow format using a tubular furnace using ammonium chloride.
- a trap mechanism was provided downstream of the reactor.
- the sample was spread out thinly on a glassy carbon (GC) boat.
- GC glassy carbon
- a GC boat containing ammonium fluoride powder was disposed upstream and downstream. The amount of ammonium chloride charged depends on the size of the reaction space, the gas flow rate, the heat treatment temperature, and the heat treatment time.
- a quartz tube having a radius of 28 mm and a length of 1200 mm was used, and 10 g of ammonium chloride was arranged upstream and downstream of 20 g of magnetic powder.
- Ar was flowed at 200 ml / min.
- Heat treatment was performed at 250 ° C., 300 ° C., 350 ° C., 400 ° C., and 450 ° C. so that the reaction time was 24 hours.
- the heat treatment temperature a low temperature at which the decomposition / oxidation reaction of Sm 2 Fe 17 is relatively small is desirable, but a temperature higher than 300 ° C. at which ammonium chloride is decomposed is selected.
- vacuum substitution may be performed at the end of the heat treatment for the purpose of removing unreacted products.
- the sample was stored in a vacuum container in a polyethylene container because unreacted material may be attached.
- the chlorinated magnetic powder is extremely stable at room temperature, it may be a glass bottle. Since this method is a solid-gas reaction, non-uniformity of the reaction becomes a problem. Therefore, it is desirable to introduce a fluidized bed or the like so that the reaction proceeds evenly.
- Example 6 Nanocoat treatment
- a fluorination treatment was examined on the magnetic powder constructed around a thin fluoride film.
- a processing solution for forming a rare earth fluoride or alkaline earth metal fluoride coating film was prepared as follows.
- the process of forming the rare earth fluoride or alkaline earth metal fluoride coating film on the magnetic powder was performed by the following method.
- the magnetic powder was produced by the same method as in Example 1. In this example, Sm 2 Fe 17 and Nd 2 Fe 17 phase magnetic powders were used. It grind
- the magnetic powder from which the solvent had been removed was transferred to a quartz boat and heat-treated at 200 ° C. for 30 minutes and 350 ° C. for 30 minutes under a reduced pressure of 1 ⁇ 10 ⁇ 3 Pa. As a result, 2 wt% of PrF 3 was treated with respect to the magnetic powder weight.
- the magnetic powder having a PrF 3 film formed thereon by the above method was hydrogenated, nitrogenated or carbonized, and fluorinated by the same method as in Examples 1 to 3. It was found that the reaction occurs uniformly by forming a film of PrF 3 around the magnetic powder. We also observed signs that hydrogen with a small ion radius was preferentially taken into the magnetic powder. Details of the effect of the PrF 3 film are unknown at present, but it is presumed that it contributes effectively for purposes such as reaction uniformity, atomic selective diffusion, and decomposition suppression.
- Example 7 Change in particle size
- the chemical reaction proceeds by atomic diffusion generated from the outer periphery of the magnetic powder accompanying the solid-gas reaction
- the crystal particle size is uniform in chemical reaction, that is, the element It greatly affects the uniformity of concentration distribution.
- particle size control is necessary in mass production.
- the diffusion rate of F atoms in the Fe-based alloy is extremely slow, particle size control is a factor that cannot be ignored. Therefore, in this example, the particle size dependence of magnetic properties was examined.
- the magnetic powder was produced by the same method as in Example 1, and the particle size was adjusted using a jet mill and a ball mill.
- typical Sm 2 Fe 17 magnetic powder was prepared.
- FIG. 13A is a perspective view schematically showing a position of an F atom that has entered a hexagonal crystal lattice having a Th 2 Zn 17 type structure.
- R is a 4f transition element or Y (the same applies to FIGS. 13B and 13C).
- FIG. 13B is a perspective view schematically showing the position of an F atom that has entered the monoclinic crystal lattice having an Nd 3 (Fe, Ti) 29 type structure.
- T is a 3d transition element other than Fe, or Al, Si, Ga, Mo, Nb, or W (the same applies to FIG. 13C).
- FIG. 13C is a perspective view schematically showing the position of an F atom that has entered a tetragonal crystal lattice having a ThMn 12 type structure.
- FIG. 14A is a (001) plane view schematically showing the displacement of Fe atoms when F atoms enter the hexagonal crystal lattice.
- FIG. 14B is a (003) plane view schematically showing displacement of Fe atoms when F atoms enter the hexagonal crystal lattice.
- the elements constituting the crystal lattice are Sm, Fe, and F.
- Fe is located at the apex of the hexagon.
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Abstract
An objective of the present invention is to improve such magnetic characteristics of a magnetic material as magnetic moment and magnetic anisotropy. A magnetic material is employed that includes either a binary alloy denoted by a chemical formula of the form R-Fe (where R is either a 4f transition element or yttrium (Y)), or a ternary alloy of the chemical formula R-Fe-T (where R is as per the foregoing description, and T is either a 3d transition element excluding iron (Fe), or else T is aluminum (Al), silicon (Si), gallium (Ga), molybdenum (Mo), niobium (Nb), or tungsten (W), provided that if T is W, then R is either a 4f transition element other than W, or Y). The alloys include either fluorine (F) atoms, nitrogen (N) atoms, hydrogen (H) atoms, or carbon (C) atoms in doping locations in the crystal lattices thereof.
Description
本発明は、4f遷移元素-3d遷移元素合金の永久磁石としての高磁気特性化の構造及び組成に関するものである。
The present invention relates to a structure and composition with high magnetic properties as a permanent magnet of a 4f transition element-3d transition element alloy.
高性能永久磁石材料としての指標には、キュリー温度,磁化及び磁気異方性の3要素が挙げられる。これらの3要素を飛躍的に向上させる方法の1つとして、母相の結晶に原子を挿入する方法が知られている。例えば、特許文献1にあるように、Sm2Fe17に非磁性元素である窒素(N)の原子を侵入させることにより、母相の磁気特性が向上する。また、非特許文献1にあるように、非磁性元素がフッ素(F)の場合、R2Fe17(Rは4f遷移元素)で最も磁気特性が向上することが計算により予測されている。実際に、非特許文献2にあるように、F原子を侵入させることで、キュリー温度が上昇することが知られている。
The index as a high-performance permanent magnet material includes three elements of Curie temperature, magnetization, and magnetic anisotropy. As one of the methods for dramatically improving these three elements, a method of inserting atoms into a parent phase crystal is known. For example, as disclosed in Patent Document 1, by introducing nitrogen (N) atoms, which are nonmagnetic elements, into Sm 2 Fe 17 , the magnetic properties of the parent phase are improved. As described in Non-Patent Document 1, when the non-magnetic element is fluorine (F), it is predicted by calculation that R 2 Fe 17 (R is a 4f transition element) improves the magnetic characteristics most. Actually, as described in Non-Patent Document 2, it is known that the Curie temperature rises by invading F atoms.
永久磁石材料の母相として既存の最高性能を誇るNd2Fe14Bは、希少資源である希土類元素の使用量(Fe元素に対するNd元素が元素構成比で14.3%)が依然として多い。これよりも希土類元素の量が少ない組成においては、磁気特性を向上させることが重要である。特許文献1に記載のSm2Fe17N3は、母相よりも磁気特性が改善されたとはいえ、依然として磁気モーメント及び磁気異方性が小さい。非特許文献1に記載のGd2Fe17F3は、磁気モーメントの増加及び磁気異方性エネルギーの増加に関して計算上の予測をしているが、結晶構造の安定性を議論しておらず実際の系として安定に存在するかは不明である。また、キュリー温度に対する言及もない。非特許文献2に記載のR2Fe17Fxは、F元素の元素分析を実施していないため、キュリー温度の上昇がF原子の効果であるか否かは不明であり、また、キュリー温度の上昇が最大でも約40℃と低い。
Nd 2 Fe 14 B, which has the highest performance as the parent phase of the permanent magnet material, still has a large amount of rare earth element used (Nd element with respect to Fe element is 14.3% in terms of element composition ratio). It is important to improve the magnetic properties in a composition having a smaller amount of rare earth element than this. Although Sm 2 Fe 17 N 3 described in Patent Document 1 has improved magnetic properties as compared with the parent phase, it still has a small magnetic moment and magnetic anisotropy. Although Gd 2 Fe 17 F 3 described in Non-Patent Document 1 makes a calculation prediction regarding an increase in magnetic moment and an increase in magnetic anisotropy energy, it does not discuss the stability of the crystal structure, but actually It is unclear whether it exists as a stable system. There is no mention of the Curie temperature. Since R 2 Fe 17 F x described in Non-Patent Document 2 has not been subjected to elemental analysis of the F element, it is unclear whether the increase in the Curie temperature is due to the effect of F atoms, and the Curie temperature The maximum rise is as low as about 40 ° C.
本発明は、従来の磁石材料よりも磁気モーメント、磁気異方性等の磁気特性に優れた磁石材料を提供することを目的とする。
An object of the present invention is to provide a magnet material that is more excellent in magnetic properties such as magnetic moment and magnetic anisotropy than conventional magnet materials.
上述の課題を解決するために本発明者が鋭意検討した結果、合金の結晶格子内の侵入位置にF原子と、N原子,H原子またはC原子とを配置することによって合金の磁気特性を向上できることを見出した。
As a result of intensive studies by the present inventor in order to solve the above-mentioned problems, the magnetic properties of the alloy are improved by arranging F atoms and N, H, or C atoms at the intrusion positions in the crystal lattice of the alloy. I found out that I can do it.
本発明は下記の構成を包含する。
本発明の磁石材料は、化学式R-Fe(式中、Rは4f遷移元素またはYである。)で表される2元系の合金、あるいは化学式R-Fe-T(式中、Rは前記の通りであり、TはFeを除く3d遷移元素、またはAl,Si,Ga,Mo,NbもしくはWである。但し、TがWである場合、RはW以外の4f遷移元素またはYである。)の3元系の合金を含み、前記合金は、結晶格子内の侵入位置にF原子と、N原子、H原子またはC原子とを含むものである。 The present invention includes the following configurations.
The magnet material of the present invention includes a binary alloy represented by the chemical formula R—Fe (wherein R is a 4f transition element or Y), or a chemical formula R—Fe—T (wherein R is T is a 3d transition element excluding Fe, or Al, Si, Ga, Mo, Nb or W. However, when T is W, R is a 4f transition element other than W or Y. )), Which contains F atoms and N, H, or C atoms at the intrusion position in the crystal lattice.
本発明の磁石材料は、化学式R-Fe(式中、Rは4f遷移元素またはYである。)で表される2元系の合金、あるいは化学式R-Fe-T(式中、Rは前記の通りであり、TはFeを除く3d遷移元素、またはAl,Si,Ga,Mo,NbもしくはWである。但し、TがWである場合、RはW以外の4f遷移元素またはYである。)の3元系の合金を含み、前記合金は、結晶格子内の侵入位置にF原子と、N原子、H原子またはC原子とを含むものである。 The present invention includes the following configurations.
The magnet material of the present invention includes a binary alloy represented by the chemical formula R—Fe (wherein R is a 4f transition element or Y), or a chemical formula R—Fe—T (wherein R is T is a 3d transition element excluding Fe, or Al, Si, Ga, Mo, Nb or W. However, when T is W, R is a 4f transition element other than W or Y. )), Which contains F atoms and N, H, or C atoms at the intrusion position in the crystal lattice.
本発明によれば、従来の磁石材料よりも磁気特性に優れた磁石材料を提供することができる。
According to the present invention, it is possible to provide a magnet material that has better magnetic properties than conventional magnet materials.
遷移金属を基にした磁性材料では、バンド分極により磁性が発現する。比較的遍歴性の強い3d遷移金属基ではハバードモデル、局在性の強い4f希土類金属基ではアンダーソンモデルによってそれぞれ記述されることが多い。ハバードモデルは電子が空間的に広がることによる運動エネルギー低下の利得と、電子同士が近づくことによるクーロンエネルギーの増加との競合により電子状態や磁気構造が決定する。また、アンダーソンモデルでは、ハバードモデルに更に伝導電子と局在電子の相互作用を考慮し、電子状態や磁気構造が決定する。本発明の原理は、一般的には3d遷移金属の単一ハバードモデルから導出される金森条件に関係する。金森条件はストーナ条件に対しクーロンエネルギーの過大評価を取り除いたものであり、強磁性発現の目安を与え、次式で表わされる。
In magnetic materials based on transition metals, magnetism is manifested by band polarization. In many cases, the 3d transition metal group having relatively strong itinerary is described by the Hubbard model, and in the 4f rare earth metal group having strong localization, the Anderson model is often used. In the Hubbard model, the electronic state and magnetic structure are determined by the competition between the gain of kinetic energy reduction due to the spatial spread of electrons and the increase of Coulomb energy due to the proximity of electrons. In the Anderson model, the electronic state and magnetic structure are determined by further considering the interaction between conduction electrons and localized electrons in the Hubbard model. The principles of the present invention generally relate to Kanamori conditions derived from a single Hubbard model of 3d transition metals. The Kanamori condition is obtained by removing the overestimation of Coulomb energy with respect to the Stoner condition.
ただし、Uはクーロンエネルギー、G(0,0)は波数ベクトル0を有する2電子間のパラメータであり3dバンド幅の逆数程度の大きさ、D(EF)はフェルミ準位における電子の状態密度をそれぞれ示す。金森条件は、強磁性が生じるためには、バンド幅がかなり大きく、かつ同時にフェルミ準位の状態密度が局所的に大きくなっていることが必要であることを示している。電子状態密度は結晶格子の増大とともに大きくなるため、単位胞の体積変化により電子状態密度は変化する。したがって、強制的や自発的な力により単位胞に体積変化を導入した場合、フェルミ準位付近での状態密度が変化することで大きな磁性の変化が生ずることが期待される。
Where U is the Coulomb energy, G (0,0) is a parameter between two electrons having a wave vector of 0 and is about the reciprocal of the 3d bandwidth, and D (E F ) is the electron density of states at the Fermi level. Respectively. The Kanamori condition indicates that in order for ferromagnetism to occur, the bandwidth needs to be quite large, and at the same time the state density of the Fermi level must be locally increased. Since the electronic state density increases with the increase of the crystal lattice, the electronic state density changes due to the volume change of the unit cell. Therefore, when a volume change is introduced into the unit cell by forced or spontaneous force, it is expected that a large change in magnetism occurs due to a change in the density of states in the vicinity of the Fermi level.
例えば、3d遷移金属合金における交換相互作用の大きさの原子間距離依存性を示すベーテ・スレータ(またはネール・スレータ)曲線は、遍歴電子磁性の相互作用が原子間距離に応じ振動することを示す曲線である。ベーテ・スレータ曲線において交換相互作用の大きさを正で最大にするためには、α-Fe(以下、単にFeと表記する)は原子間距離が短すぎ、Co,Niは原子間距離が広すぎることが知られている。これは、Feでは電子の遍歴性が強すぎ局在電子が少ないために交換相互作用が小さく、またCo,Niでは局在性が強すぎ波動関数の重なりが小さいために交換相互作用が小さいことを意味する。つまり、Feでは原子間距離を拡げ局在性を増すことにより、またCo,Niでは原子間距離を縮め遍歴性を増すことにより、それぞれ交換相互作用の増大が可能であることを意味する。また、このほかにアンダーソンモデルから予測でき、また実際に観測されているRKKY相互作用では、原子に局在した電子の電場により周囲の伝導電子がスピン偏極を受け、それにより隣の原子の局在電子と相互作用をする。RKKY相互作用も原子間距離に応じ交換相互作用が振動する。
For example, the Bethe-Slater (or Neel-Slater) curve showing the interatomic distance dependence of the magnitude of the exchange interaction in 3d transition metal alloys shows that itinerant electron magnetic interactions oscillate with interatomic distance It is a curve. In order to maximize the magnitude of the exchange interaction in the Bethe-Slater curve, α-Fe (hereinafter simply referred to as Fe) has a short interatomic distance, and Co and Ni have a wide interatomic distance. It is known that too. This is because in Fe, the itinerant nature of electrons is too strong and there are few localized electrons, so the exchange interaction is small, and in Co and Ni, the localization is too strong and the overlap of wave functions is small, so the exchange interaction is small. Means. That is, it is possible to increase the exchange interaction by increasing the interatomic distance and increasing the localization in Fe, and by reducing the interatomic distance and increasing the itinerant in Co and Ni. In addition, in the RKKY interaction that can be predicted from the Anderson model and is actually observed, the surrounding conduction electrons are subjected to spin polarization by the electric field of the electrons localized in the atoms, thereby causing the local atoms to be localized. Interacts with electrons. In the RKKY interaction, the exchange interaction oscillates according to the interatomic distance.
本発明の強磁性フッ素化合物は、母相の4f遷移元素-Fe元素の合金にF原子と他の非磁性原子(H,C,N)が侵入することで、Feのフェルミ準位付近での状態密度の低下、及びFeの局在性の増大が生じ、磁化増加、及びキュリー温度上昇の効果を引き起こす。さらにF原子を含めた原子の侵入、及びF原子の強い電気陰性度により、磁気異方性の改善が生じる。特に、化学式R2(Fe,T)17,化学式R3(Fe,T)29,化学式R(Fe,T)12(Rは4f遷移元素またはYであり、TはFeを除く3d遷移元素、またはAl,Si,Ga,Mo,NbもしくはWである)などのCaCu5構造を基調とした結晶構造を有する相全般に対し、F原子を含めた非磁性原子の導入により母相の磁気特性が飛躍的に向上する。一般にこれらの構造では、N原子が化学式R2(Fe,T)17Nx(0<x≦3),化学式R3(Fe,T)29Ny(0<y≦4),化学式R(Fe,T)12Nz(0<z≦1)のように配置することが知られており、F原子はN原子と同様に配置する。非磁性原子の導入量が多すぎる場合、強すぎる局在性によりFeバンド幅が狭くなりすぎるため、金森条件を満足せず強磁性は弱まることになる。すなわち、F原子を含めた非磁性原子による磁化、及びキュリー温度は、Fe原子間距離が短いサイトを有する結晶構造においてのみ顕著に増加及び上昇するのである。一般にFe原子間の交換相互作用の正負が切り替わる値は約0.245nmである(交換相互作用が最大値となるFe原子間距離は、0.260nm付近である)。0.245nmよりも短いFe原子間距離を有する結晶構造において、F原子導入による強磁性増大効果が顕著である。
In the ferromagnetic fluorine compound of the present invention, F atoms and other nonmagnetic atoms (H, C, N) penetrate into the alloy of the 4f transition element-Fe element of the parent phase, so that near the Fermi level of Fe. A decrease in the density of states and an increase in the localization of Fe occur, causing the effects of increased magnetization and increased Curie temperature. Furthermore, the penetration of atoms including F atoms and the strong electronegativity of F atoms cause an improvement in magnetic anisotropy. In particular, the chemical formula R 2 (Fe, T) 17 , the chemical formula R 3 (Fe, T) 29 , the chemical formula R (Fe, T) 12 (R is a 4f transition element or Y, T is a 3d transition element excluding Fe, In addition, with respect to all phases having a crystal structure based on the CaCu 5 structure such as Al, Si, Ga, Mo, Nb or W), the magnetic characteristics of the parent phase can be obtained by introducing nonmagnetic atoms including F atoms. Improve dramatically. In general, in these structures, the N atom has the chemical formula R 2 (Fe, T) 17 N x (0 <x ≦ 3), the chemical formula R 3 (Fe, T) 29 N y (0 <y ≦ 4), the chemical formula R ( It is known to arrange as Fe, T) 12 N z (0 <z ≦ 1), and F atoms are arranged in the same manner as N atoms. When the introduced amount of nonmagnetic atoms is too large, the Fe band width becomes too narrow due to too strong localization, so that the Kanamori condition is not satisfied and the ferromagnetism is weakened. That is, the magnetization due to nonmagnetic atoms including F atoms and the Curie temperature increase and increase notably only in a crystal structure having a site where the distance between Fe atoms is short. In general, the value at which the positive / negative exchange interaction between Fe atoms is switched is about 0.245 nm (the distance between Fe atoms at which the exchange interaction is maximized is about 0.260 nm). In a crystal structure having an Fe interatomic distance shorter than 0.245 nm, the effect of increasing ferromagnetism by introducing F atoms is remarkable.
母相をフッ素化する方法として、フッ化アンモニウム(NH4F),酸性フッ化アンモニウム(NH4F・HF),ケイフッ化アンモニウム((NH4F)2SiF6),ほうフッ化アンモニウム(NH4BF4)などの熱分解・昇華で発生するガスを利用する方法、及び三フッ化窒素(NF3),三フッ化ホウ素(BF3),六フッ化硫黄(SF6)フッ化水素,フッ素などのガスを利用する方法がある。各ガス同士の反応性によるが、これらを混合したり、同時に使用することも可能である。
As a method for fluorinating the mother phase, ammonium fluoride (NH 4 F), acidic ammonium fluoride (NH 4 F · HF), ammonium silicofluoride ((NH 4 F) 2 SiF 6 ), ammonium borofluoride (NH 4 BF 4 ) and other methods using gas generated by pyrolysis and sublimation, and nitrogen trifluoride (NF 3 ), boron trifluoride (BF 3 ), sulfur hexafluoride (SF 6 ) hydrogen fluoride, There is a method using a gas such as fluorine. Depending on the reactivity of each gas, they can be mixed or used simultaneously.
例えば、Sm2Fe17に対しNH4Fの昇華により400℃よりも低い温度、望ましくは350℃よりも低い温度でフッ素化熱処理を行うことで、下記の特徴を有する強磁性フッ素化合物磁石を合成することに成功した。本発明の原理は、上述のFeの特徴に主として依存しており、F原子を含めた非磁性原子が侵入することで結晶格子体積の増加に伴う幾何学的な効果が生じ、磁気モーメントの大きな増加とキュリー温度の上昇が得られることにある。
For example, a ferromagnetic fluorine compound magnet having the following characteristics is synthesized by performing fluorination heat treatment at a temperature lower than 400 ° C., preferably lower than 350 ° C. by sublimation of NH 4 F with respect to Sm 2 Fe 17. Succeeded in doing. The principle of the present invention mainly depends on the above-described characteristics of Fe, and when a nonmagnetic atom including an F atom enters, a geometrical effect is generated as the crystal lattice volume increases, and a magnetic moment is large. There is an increase and an increase in Curie temperature.
さらに、磁化の増加及びキュリー温度の上昇は、フッ素原子の強い電気陰性度によるFeの局在化の効果によっても生じる。4f遷移元素の種類に応じ侵入位置の空間的大きさに違いがあるため、磁化の増加率及びキュリー温度上昇率は4f遷移元素の種類に応じ異なることが特徴である。
Furthermore, the increase in magnetization and the increase in the Curie temperature are also caused by the effect of Fe localization due to the strong electronegativity of fluorine atoms. Since there is a difference in the spatial size of the intrusion position depending on the type of 4f transition element, the increase rate of magnetization and the Curie temperature increase rate are different depending on the type of 4f transition element.
以下、本発明について詳細に説明する。
Hereinafter, the present invention will be described in detail.
本発明は、結晶格子内の侵入位置にF原子と、N原子,H原子またはC原子とを配置した化学式R-Fe(式中、Rは4f遷移元素またはYである。)の2元系、あるいは化学式R-Fe-T(式中、Rは前記の通りであり、TはFeを除く3d遷移元素、またはAl,Si,Ga,Mo,NbもしくはWである。但し、TがWである場合、RはW以外の4f遷移元素またはYである。)の3元系の合金を含む磁石材料に関する。
The present invention is a binary system of the chemical formula R—Fe (wherein R is a 4f transition element or Y) in which an F atom and an N atom, H atom or C atom are arranged at the intrusion position in the crystal lattice. Or the chemical formula R-Fe-T (wherein R is as defined above, T is a 3d transition element excluding Fe, or Al, Si, Ga, Mo, Nb or W, provided that T is W In some cases, R is a 4f transition element other than W or Y.) relates to a magnet material including a ternary alloy.
好ましくは、Rがランタノイドである合金を含む磁石材料、特に好ましくは、RがSm,Er,Tm,Pr,Nd,TbまたはDyである合金を含む磁石材料、最も好ましくは、RがSmまたはNdである合金を含む磁石材料に関する。また、好ましくは、TがFeを除く3d遷移元素である合金を含む磁石材料、特に好ましくは、TがTiである合金を含む磁石材料に関する。
Preferably, a magnetic material comprising an alloy wherein R is a lanthanoid, particularly preferably a magnetic material comprising an alloy wherein R is Sm, Er, Tm, Pr, Nd, Tb or Dy, most preferably R is Sm or Nd. The present invention relates to a magnet material containing an alloy. In addition, the present invention preferably relates to a magnet material containing an alloy in which T is a 3d transition element excluding Fe, and particularly preferably relates to a magnet material containing an alloy in which T is Ti.
合金の結晶格子内の侵入位置にF原子と、N原子,H原子またはC原子とを配置することにより磁気特性を向上させることができる。
The magnetic properties can be improved by arranging F atoms and N, H, or C atoms at the intrusion position in the crystal lattice of the alloy.
1.F原子及びH原子含有合金
本発明の一実施態様としては、結晶格子内の侵入位置にF原子とH原子とを配置した化学式R-Feの2元系、または化学式R-Fe-Tの3元系の合金を含む磁石材料が挙げられる。 1. F-Atom and H-Atom Containing Alloy As one embodiment of the present invention, a binary system of the chemical formula R—Fe in which F atoms and H atoms are arranged at the intrusion positions in the crystal lattice, or a chemical formula R—Fe—T 3 Examples thereof include a magnet material containing a base alloy.
本発明の一実施態様としては、結晶格子内の侵入位置にF原子とH原子とを配置した化学式R-Feの2元系、または化学式R-Fe-Tの3元系の合金を含む磁石材料が挙げられる。 1. F-Atom and H-Atom Containing Alloy As one embodiment of the present invention, a binary system of the chemical formula R—Fe in which F atoms and H atoms are arranged at the intrusion positions in the crystal lattice, or a chemical formula R—Fe—
結晶格子内の侵入位置にF原子とH原子とを導入する方法としては、例えば、フッ化アンモニウム(NH4F),酸性フッ化アンモニウム(NH4F・HF),ケイフッ化アンモニウム((NH4F)2SiF6),ほうフッ化アンモニウム(NH4BF4)などの熱分解・昇華により発生するフッ化水素ガスを用いた熱処理により水素化及びフッ素化を同時に実施する方法が挙げられる。また、既に知られている水素化法及びフッ素化法を別々に実施することも可能である。その場合、水素化を先に実施しておくことでその後のフッ素化が容易に生じるので望ましい。しかしながら、水素原子とフッ素原子が結晶格子内の侵入位置に適当な占有率で共存していればよいため、フッ素化した後に水素化してもよい。
As a method for introducing F atoms and H atoms into the intrusion position in the crystal lattice, for example, ammonium fluoride (NH 4 F), ammonium acid fluoride (NH 4 F · HF), ammonium silicofluoride ((NH 4 F) 2 SiF 6 ), ammonium borofluoride (NH 4 BF 4 ) and the like, and a method of simultaneously performing hydrogenation and fluorination by heat treatment using hydrogen fluoride gas generated by thermal decomposition and sublimation. It is also possible to carry out the already known hydrogenation method and fluorination method separately. In that case, it is desirable to carry out hydrogenation in advance, since subsequent fluorination easily occurs. However, since hydrogen atoms and fluorine atoms only need to coexist at an intrusion position in the crystal lattice with an appropriate occupation ratio, they may be hydrogenated after fluorination.
本発明に用いる合金は、化学式R2(Fe,T)17,化学式R3(Fe,T)29,化学式R(Fe,T)12相を用いることが望ましい。これら合金はCaCu5構造を基本に、その3次元的な積み方の違いにより区別される。本発明は、CaCu5構造を基本とした結晶構造を有する相全般に対して適用可能である。そのため、化学式RT5,化学式RT7相や、より複雑な多元系に対して適用可能である。
The alloy used in the present invention preferably uses the chemical formula R 2 (Fe, T) 17 , the chemical formula R 3 (Fe, T) 29 , and the chemical formula R (Fe, T) 12 phase. These alloys are distinguished on the basis of the CaCu 5 structure by their three-dimensional stacking method. The present invention is applicable to all phases having a crystal structure based on the CaCu 5 structure. Therefore, the present invention can be applied to the chemical formula RT 5 , chemical formula RT 7 phase, and more complex multi-component systems.
しかしながら、本発明における合金としては、
(1)化学式R2Fe17HαFx(0<α<5、かつ0<x≦3、かつ0<α+x≦5)、
(2)化学式R3(Fe,T)29HβFy(0<β<6、かつ0<y≦4、かつ0<β+y≦6)または
(3)化学式R(Fe,T)12HγFz(0<γ<1、かつ0<z<1、かつ0<γ+z≦1)
で表されるものが好ましい。 However, as an alloy in the present invention,
(1) Chemical formula R 2 Fe 17 H α F x (0 <α <5, 0 <x ≦ 3, and 0 <α + x ≦ 5),
(2) Chemical formula R 3 (Fe, T) 29 H β F y (0 <β <6 and 0 <y ≦ 4 and 0 <β + y ≦ 6) or (3) Chemical formula R (Fe, T) 12 H γ F z (0 <γ <1, 0 <z <1, and 0 <γ + z ≦ 1)
The thing represented by these is preferable.
(1)化学式R2Fe17HαFx(0<α<5、かつ0<x≦3、かつ0<α+x≦5)、
(2)化学式R3(Fe,T)29HβFy(0<β<6、かつ0<y≦4、かつ0<β+y≦6)または
(3)化学式R(Fe,T)12HγFz(0<γ<1、かつ0<z<1、かつ0<γ+z≦1)
で表されるものが好ましい。 However, as an alloy in the present invention,
(1) Chemical formula R 2 Fe 17 H α F x (0 <α <5, 0 <x ≦ 3, and 0 <α + x ≦ 5),
(2) Chemical formula R 3 (Fe, T) 29 H β F y (0 <β <6 and 0 <y ≦ 4 and 0 <β + y ≦ 6) or (3) Chemical formula R (Fe, T) 12 H γ F z (0 <γ <1, 0 <z <1, and 0 <γ + z ≦ 1)
The thing represented by these is preferable.
α+x,β+y、及びγ+zの上限は、侵入位置の数により制限される。本発明における合金の組成は、電子線マイクロアナライザ(Electron probe micro analyzer、EPMA)、飛行時間型2次イオン質量分析計(Time-of-flight secondary ion mass spectrometer、TOF-SIMS)により決定される。
The upper limit of α + x, β + y, and γ + z is limited by the number of intrusion positions. The composition of the alloy in the present invention is determined by an electron probe microanalyzer (EPMA) and a time-of-flight secondary ion mass spectrometer (TOF-SIMS).
上記(1)の化学式において、RがSm,ErまたはTmであり、1≦x(つまり、0<α≦4、かつ1≦x≦3、かつ1<α+x≦5)の場合、合金は1軸磁気異方性となる。上記(2)の化学式において、RがSm、ErまたはTmであり、2≦y(つまり、0<β≦4、かつ2≦y≦4、かつ2<β+y≦6)の場合、合金は1軸磁気異方性となる。上記(3)の化学式において、RがPr,Nd,TbまたはDyであり、0.5≦z(つまり、0<γ≦0.5、かつ0.5≦z<1、かつ0.5<γ+z≦1)の場合、合金は1軸磁気異方性となる。
In the chemical formula (1), when R is Sm, Er or Tm and 1 ≦ x (that is, 0 <α ≦ 4, 1 ≦ x ≦ 3, and 1 <α + x ≦ 5), the alloy is 1 It becomes axial magnetic anisotropy. In the chemical formula (2), when R is Sm, Er or Tm and 2 ≦ y (that is, 0 <β ≦ 4, 2 ≦ y ≦ 4, and 2 <β + y ≦ 6), the alloy is 1 It becomes axial magnetic anisotropy. In the chemical formula (3), R is Pr, Nd, Tb or Dy, and 0.5 ≦ z (that is, 0 <γ ≦ 0.5, 0.5 ≦ z <1, and 0.5 < In the case of γ + z ≦ 1), the alloy has uniaxial magnetic anisotropy.
F原子及びH原子を含有する合金は、F原子及びH原子を導入するための熱処理の温度に依存して、希土類フッ化物,希土類酸フッ化物,鉄、及び鉄フッ化物の少なくともいずれか1種を含む。
The alloy containing F atoms and H atoms is at least one of rare earth fluoride, rare earth oxyfluoride, iron, and iron fluoride depending on the temperature of the heat treatment for introducing F atoms and H atoms. including.
2.F原子及びN原子含有合金
本発明の一実施態様としては、結晶格子内の侵入位置にF原子とN原子とを配置した化学式R-Feの2元系の合金、または化学式R-Fe-Tの3元系の合金を含む磁石材料が挙げられる。F原子とN原子を配置することでキュリー温度の上昇,磁気モーメントの増加、及び磁気異方性の改善が可能となる。 2. F-Atom and N-Atom Containing Alloy As an embodiment of the present invention, a binary alloy of the chemical formula R—Fe in which an F atom and an N atom are arranged at an intrusion position in a crystal lattice, or a chemical formula R—Fe—T A magnetic material containing a ternary alloy of Arranging F atoms and N atoms makes it possible to increase the Curie temperature, increase the magnetic moment, and improve the magnetic anisotropy.
本発明の一実施態様としては、結晶格子内の侵入位置にF原子とN原子とを配置した化学式R-Feの2元系の合金、または化学式R-Fe-Tの3元系の合金を含む磁石材料が挙げられる。F原子とN原子を配置することでキュリー温度の上昇,磁気モーメントの増加、及び磁気異方性の改善が可能となる。 2. F-Atom and N-Atom Containing Alloy As an embodiment of the present invention, a binary alloy of the chemical formula R—Fe in which an F atom and an N atom are arranged at an intrusion position in a crystal lattice, or a chemical formula R—Fe—T A magnetic material containing a ternary alloy of Arranging F atoms and N atoms makes it possible to increase the Curie temperature, increase the magnetic moment, and improve the magnetic anisotropy.
本発明における合金としては、
(4)化学式R2Fe17NαFx(0<α<3、かつ0<x<3、かつ0<α+x≦3)、
(5)化学式R3(Fe,T)29NβFy(0<β<4、かつ0<y<4、かつ0<β+y≦4)または
(6)化学式R(Fe,T)12NγFz(0<γ<1、かつ0<z<1、かつ0<γ+z≦1)
で表されるものが好ましい。 As an alloy in the present invention,
(4) Chemical formula R 2 Fe 17 N α F x (0 <α <3 and 0 <x <3 and 0 <α + x ≦ 3),
(5) Chemical formula R 3 (Fe, T) 29 N β F y (0 <β <4 and 0 <y <4 and 0 <β + y ≦ 4) or (6) Chemical formula R (Fe, T) 12 N γ F z (0 <γ <1, 0 <z <1, and 0 <γ + z ≦ 1)
The thing represented by these is preferable.
(4)化学式R2Fe17NαFx(0<α<3、かつ0<x<3、かつ0<α+x≦3)、
(5)化学式R3(Fe,T)29NβFy(0<β<4、かつ0<y<4、かつ0<β+y≦4)または
(6)化学式R(Fe,T)12NγFz(0<γ<1、かつ0<z<1、かつ0<γ+z≦1)
で表されるものが好ましい。 As an alloy in the present invention,
(4) Chemical formula R 2 Fe 17 N α F x (0 <α <3 and 0 <x <3 and 0 <α + x ≦ 3),
(5) Chemical formula R 3 (Fe, T) 29 N β F y (0 <β <4 and 0 <y <4 and 0 <β + y ≦ 4) or (6) Chemical formula R (Fe, T) 12 N γ F z (0 <γ <1, 0 <z <1, and 0 <γ + z ≦ 1)
The thing represented by these is preferable.
α+x,β+y、及びγ+zの上限は、侵入位置の数により制限される。本発明における合金の組成は、EPMA,TOF-SIMSにより決定される。
The upper limit of α + x, β + y, and γ + z is limited by the number of intrusion positions. The composition of the alloy in the present invention is determined by EPMA, TOF-SIMS.
上記(4)の化学式において、RがSm,ErまたはTmであり、1≦α+x(つまり、0<α<3、かつ0<x<3、かつ1≦α+x≦3)の場合、合金は1軸磁気異方性となる。上記(5)の化学式において、RがSm,ErまたはTmであり、2≦β+y(つまり、0<β<4、かつ0<y<4、かつ2≦β+y≦4)の場合、合金は1軸磁気異方性となる。上記(6)の化学式において、RがPr,Nd,TbまたはDyであり、0.5≦γ+z(つまり、0<γ<1、かつ0<z<1、かつ0.5≦γ+z≦1)の場合、合金は1軸磁気異方性となる。
In the chemical formula (4) above, when R is Sm, Er or Tm and 1 ≦ α + x (that is, 0 <α <3 and 0 <x <3 and 1 ≦ α + x ≦ 3), the alloy is 1 It becomes axial magnetic anisotropy. In the chemical formula (5) above, when R is Sm, Er or Tm and 2 ≦ β + y (that is, 0 <β <4 and 0 <y <4 and 2 ≦ β + y ≦ 4), the alloy is 1 It becomes axial magnetic anisotropy. In the chemical formula (6), R is Pr, Nd, Tb, or Dy, and 0.5 ≦ γ + z (that is, 0 <γ <1, 0 <z <1, and 0.5 ≦ γ + z ≦ 1) In this case, the alloy has uniaxial magnetic anisotropy.
窒素原子とフッ素原子が結晶格子内の侵入位置に適当な占有率で共存していればよいため、F原子とN原子とを導入する方法としては特に限定されない。例えば、合金を三フッ化窒素の存在下で熱処理する方法を挙げることができる。
Since a nitrogen atom and a fluorine atom only need to coexist at an intrusion position in the crystal lattice with an appropriate occupation ratio, the method for introducing the F atom and the N atom is not particularly limited. For example, a method of heat-treating the alloy in the presence of nitrogen trifluoride can be mentioned.
本発明における合金は、熱処理温度に依存して、希土類窒化物,希土類フッ化物,希土類酸フッ化物,鉄、及び鉄フッ化物の少なくともいずれか1種を含む。
The alloy in the present invention contains at least one of rare earth nitride, rare earth fluoride, rare earth oxyfluoride, iron, and iron fluoride depending on the heat treatment temperature.
3.F原子及びC原子含有合金
本発明の一実施態様としては、結晶格子内の侵入位置にF原子とC原子とを配置した化学式R-Feの2元系、または化学式R-Fe-Tの3元系の合金を含む磁石材料が挙げられる。F原子とC原子を配置することで結晶格子の熱安定性の向上,キュリー温度の上昇,磁気モーメントの増加、及び磁気異方性の改善が可能となる。 3. F- and C-atom-containing alloys As one embodiment of the present invention, a binary system of chemical formula R—Fe in which F atoms and C atoms are arranged at penetration positions in the crystal lattice, or 3 of chemical formula R—Fe—T Examples thereof include a magnet material containing a base alloy. Arranging F atoms and C atoms makes it possible to improve the thermal stability of the crystal lattice, increase the Curie temperature, increase the magnetic moment, and improve the magnetic anisotropy.
本発明の一実施態様としては、結晶格子内の侵入位置にF原子とC原子とを配置した化学式R-Feの2元系、または化学式R-Fe-Tの3元系の合金を含む磁石材料が挙げられる。F原子とC原子を配置することで結晶格子の熱安定性の向上,キュリー温度の上昇,磁気モーメントの増加、及び磁気異方性の改善が可能となる。 3. F- and C-atom-containing alloys As one embodiment of the present invention, a binary system of chemical formula R—Fe in which F atoms and C atoms are arranged at penetration positions in the crystal lattice, or 3 of chemical formula R—Fe—T Examples thereof include a magnet material containing a base alloy. Arranging F atoms and C atoms makes it possible to improve the thermal stability of the crystal lattice, increase the Curie temperature, increase the magnetic moment, and improve the magnetic anisotropy.
本発明における合金としては、
(7)化学式R2Fe17CαFx(0<α<3、かつ0<x<3、かつ0<α+x≦3)、
(8)化学式R3(Fe,T)29CβFy(0<β<4、かつ0<y<4、かつ0<β+y≦4)または
(9)化学式R(Fe,T)12CγFz(0<γ<1、かつ0<z<1、かつ0<γ+z≦1)
で表されるものが好ましい。 As an alloy in the present invention,
(7) Chemical formula R 2 Fe 17 C α F x (0 <α <3, and 0 <x <3, and 0 <α + x ≦ 3),
(8) Chemical formula R 3 (Fe, T) 29 C β F y (0 <β <4 and 0 <y <4 and 0 <β + y ≦ 4) or (9) Chemical formula R (Fe, T) 12 C γ F z (0 <γ <1, 0 <z <1, and 0 <γ + z ≦ 1)
The thing represented by these is preferable.
(7)化学式R2Fe17CαFx(0<α<3、かつ0<x<3、かつ0<α+x≦3)、
(8)化学式R3(Fe,T)29CβFy(0<β<4、かつ0<y<4、かつ0<β+y≦4)または
(9)化学式R(Fe,T)12CγFz(0<γ<1、かつ0<z<1、かつ0<γ+z≦1)
で表されるものが好ましい。 As an alloy in the present invention,
(7) Chemical formula R 2 Fe 17 C α F x (0 <α <3, and 0 <x <3, and 0 <α + x ≦ 3),
(8) Chemical formula R 3 (Fe, T) 29 C β F y (0 <β <4 and 0 <y <4 and 0 <β + y ≦ 4) or (9) Chemical formula R (Fe, T) 12 C γ F z (0 <γ <1, 0 <z <1, and 0 <γ + z ≦ 1)
The thing represented by these is preferable.
α+x,β+y、及びγ+zの上限は、侵入位置の数により制限される。本発明における合金の組成はEPMA,TOF-SIMSにより決定される。
The upper limit of α + x, β + y, and γ + z is limited by the number of intrusion positions. The composition of the alloy in the present invention is determined by EPMA, TOF-SIMS.
上記(7)の化学式において、RがSm,ErまたはTmであり、1≦α+x(つまり、0<α<3、かつ0<x<3、かつ1≦α+x≦3)の場合、合金は1軸磁気異方性となる。上記(8)の化学式において、RがSm,ErまたはTmであり、2≦β+y(つまり、0<β<4、かつ0<y<4、かつ2≦β+y≦4)の場合、合金は1軸磁気異方性となる。上記(9)の化学式において、RがPr,Nd,TbまたはDyであり、0.5≦γ+z(つまり、0<γ<1、かつ0<z<1、かつ0.5≦γ+z≦1)の場合、合金は1軸磁気異方性となる。
In the chemical formula (7), when R is Sm, Er or Tm and 1 ≦ α + x (that is, 0 <α <3 and 0 <x <3 and 1 ≦ α + x ≦ 3), the alloy is 1 It becomes axial magnetic anisotropy. In the chemical formula (8), when R is Sm, Er or Tm and 2 ≦ β + y (that is, 0 <β <4 and 0 <y <4 and 2 ≦ β + y ≦ 4), the alloy is 1 It becomes axial magnetic anisotropy. In the chemical formula (9), R is Pr, Nd, Tb or Dy, and 0.5 ≦ γ + z (that is, 0 <γ <1, and 0 <z <1, and 0.5 ≦ γ + z ≦ 1) In this case, the alloy has uniaxial magnetic anisotropy.
炭素原子とフッ素原子が結晶格子内の侵入位置に適当な占有率で共存していればよいため、F原子とC原子とを導入する方法としては特に限定されない。例えば、合金を炭化水素ガス及びフッ素ガスを使用して、またはフルオロカーボンを使用して熱処理する方法を挙げることができる。
Since the carbon atom and the fluorine atom only need to coexist at the penetration position in the crystal lattice with an appropriate occupation ratio, the method for introducing the F atom and the C atom is not particularly limited. For example, a method of heat-treating the alloy using a hydrocarbon gas and a fluorine gas, or using a fluorocarbon can be mentioned.
F原子及びC原子含有合金は、熱処理温度に依存して、希土類フッ化物,希土類酸フッ化物,鉄、及び鉄フッ化物の少なくともいずれか1種を含む。
The F atom and C atom containing alloy contains at least one of rare earth fluoride, rare earth oxyfluoride, iron, and iron fluoride depending on the heat treatment temperature.
4.磁粉作製
(1)母相合金の作製:
RとFeを混合して真空あるいは不活性ガス中または還元ガス雰囲気中で溶解し組成を均一化する(溶解鋳造法)。得られたR-Fe系母合金をボールミルを用い不活性ガス中で粗粉砕する。 4). Magnetic powder preparation (1) Preparation of parent phase alloy:
R and Fe are mixed and dissolved in a vacuum or in an inert gas or a reducing gas atmosphere to homogenize the composition (dissolution casting method). The obtained R—Fe based master alloy is coarsely pulverized in an inert gas using a ball mill.
(1)母相合金の作製:
RとFeを混合して真空あるいは不活性ガス中または還元ガス雰囲気中で溶解し組成を均一化する(溶解鋳造法)。得られたR-Fe系母合金をボールミルを用い不活性ガス中で粗粉砕する。 4). Magnetic powder preparation (1) Preparation of parent phase alloy:
R and Fe are mixed and dissolved in a vacuum or in an inert gas or a reducing gas atmosphere to homogenize the composition (dissolution casting method). The obtained R—Fe based master alloy is coarsely pulverized in an inert gas using a ball mill.
上記の方法以外にも安価な方法としては、酸化サマリウム粉と鉄粉を粒状金属カルシウムと混合して、不活性ガス雰囲気中で加熱反応させる還元拡散法などが使用できる。Sm2Fe17の包晶温度以下で拡散反応させると共に、鉄粉粒度を選択することでSmの拡散距離をある程度制御できるので、残留のα-Fe相の少ない単相合金が製造しやすく、溶解鋳造法では不可欠な均一化熱処理が不要である。Sm2Fe17合金が直接粉末として得られるため、粗粉砕工程も不要である。また、粒径のより小さな原料粉を得るためには、SmとFeの硫酸水溶液から水酸化物を沈殿させ、大気焼成することで微結晶酸化物を得ることができる。微粉砕を必要としない粒径数μmの磁粉を作製できる。
As an inexpensive method other than the above method, a reduction diffusion method in which samarium oxide powder and iron powder are mixed with granular metallic calcium and heated in an inert gas atmosphere can be used. Since the diffusion distance of Sm 2 Fe 17 is not higher than the peritectic temperature and the iron powder particle size is selected, the diffusion distance of Sm can be controlled to some extent. The casting method does not require indispensable uniform heat treatment. Since the Sm 2 Fe 17 alloy is obtained directly as a powder, a coarse pulverization step is not necessary. Further, in order to obtain a raw material powder having a smaller particle size, a microcrystalline oxide can be obtained by precipitating a hydroxide from a sulfuric acid aqueous solution of Sm and Fe and firing in the air. Magnetic powder having a particle size of several μm that does not require fine pulverization can be produced.
一方、ナノコンポジット磁石用磁粉としては、結晶粒径が数10nmから数100nmの多結晶から構成される粒径が数μm~数10μmの超急冷薄帯粉が必要である。薄帯粉は単ロールや双ロールなどの回転するロールの表面に、溶解させた母合金をアルゴンガスなどの不活性ガスあるいは還元ガス雰囲気で噴射急冷する液体超急冷法によって得られる。微細な合金組織を得る方法としては、水素化・分解・脱水素化・再結合(Hydrogenation Decomposition Desorption Recombination、HDDR)法も有用である。
On the other hand, as the magnetic powder for nanocomposite magnet, ultra-quenched ribbon powder having a grain size of several μm to several tens of μm composed of a polycrystal having a crystal grain size of several tens to several hundreds of nm is required. The ribbon powder is obtained by a liquid superquenching method in which a molten mother alloy is jetted and cooled in an inert gas or reducing gas atmosphere such as argon gas on the surface of a rotating roll such as a single roll or a twin roll. As a method for obtaining a fine alloy structure, a hydrogenation, decomposition, dehydrogenation, and recombination (HDR) method is also useful.
また、ナノ粒子プロセスや薄膜プロセスによっても母相合金の作製が可能である。例えば、気相法では、熱CVD法,プラズマCVD法,分子線エピタキシー法,スパッタ法,EB蒸着法,反応性蒸着法,レーザアブレーション法,抵抗加熱蒸着法などがある。また液相法では、共沈法,マイクロ波加熱法,ミセル法,逆ミセル法,水熱合成法,ゾルゲル法などがある。
Also, a parent phase alloy can be produced by a nanoparticle process or a thin film process. For example, the vapor phase method includes a thermal CVD method, a plasma CVD method, a molecular beam epitaxy method, a sputtering method, an EB vapor deposition method, a reactive vapor deposition method, a laser ablation method, a resistance heating vapor deposition method and the like. The liquid phase method includes coprecipitation method, microwave heating method, micelle method, reverse micelle method, hydrothermal synthesis method, sol-gel method and the like.
以上の方法で得られた母合金や母合金粉は、必要に応じて粗粉砕する必要がある。例えば、不活性ガス雰囲気中や還元ガス雰囲気中でボールミル、またはジェットミルにより機械的に粉砕する方法がある。また、HDDR法も有効であり、この方法により微細組織を形成することは、保磁力発現において有効である。当然ながら、フッ化水素ガス処理後に、粉砕することでも保磁力は発現する。
The mother alloy or mother alloy powder obtained by the above method needs to be coarsely pulverized as necessary. For example, there is a method of mechanically pulverizing with a ball mill or a jet mill in an inert gas atmosphere or a reducing gas atmosphere. The HDDR method is also effective, and forming a fine structure by this method is effective in coercive force expression. Of course, the coercive force is also exhibited by pulverization after the hydrogen fluoride gas treatment.
(2)フッ素化処理,水素化処理,窒素化処理、及び炭素化処理:
フッ素原子と、水素原子,窒素原子または炭素原子とを導入する方法としては、以下の実施例1~3に記載するような方法があるが、いずれもガスによる固気反応である。固気反応の工程では、均一な組成を得るために、粉体の表面を満遍なくガスに接触させることが重要である。特に、大量の粉体をガス処理する際に問題となるため、流動床などにより粉体を絶えず流動・撹拌することが好ましい。また、元素侵入反応は拡散律速なので、粉体の粒度が小さいほど迅速に一様な濃度分布を有する粉体を得ることができる。しかし、粒度が小さすぎると安定な流動が不可能になるので自ずと限界があり、10μmから数100μmの粒径が適当である。 (2) Fluorination treatment, hydrogenation treatment, nitrogenation treatment, and carbonization treatment:
As a method for introducing a fluorine atom and a hydrogen atom, a nitrogen atom, or a carbon atom, there are methods as described in Examples 1 to 3 below, and all are solid-gas reactions by gas. In the solid-gas reaction process, in order to obtain a uniform composition, it is important to uniformly contact the surface of the powder with the gas. In particular, since a problem occurs when a large amount of powder is gas-treated, it is preferable to constantly flow and agitate the powder using a fluidized bed or the like. In addition, since the element intrusion reaction is diffusion-controlled, a powder having a uniform concentration distribution can be obtained more quickly as the particle size of the powder is smaller. However, if the particle size is too small, a stable flow becomes impossible, so there is a limit naturally, and a particle size of 10 μm to several 100 μm is appropriate.
フッ素原子と、水素原子,窒素原子または炭素原子とを導入する方法としては、以下の実施例1~3に記載するような方法があるが、いずれもガスによる固気反応である。固気反応の工程では、均一な組成を得るために、粉体の表面を満遍なくガスに接触させることが重要である。特に、大量の粉体をガス処理する際に問題となるため、流動床などにより粉体を絶えず流動・撹拌することが好ましい。また、元素侵入反応は拡散律速なので、粉体の粒度が小さいほど迅速に一様な濃度分布を有する粉体を得ることができる。しかし、粒度が小さすぎると安定な流動が不可能になるので自ずと限界があり、10μmから数100μmの粒径が適当である。 (2) Fluorination treatment, hydrogenation treatment, nitrogenation treatment, and carbonization treatment:
As a method for introducing a fluorine atom and a hydrogen atom, a nitrogen atom, or a carbon atom, there are methods as described in Examples 1 to 3 below, and all are solid-gas reactions by gas. In the solid-gas reaction process, in order to obtain a uniform composition, it is important to uniformly contact the surface of the powder with the gas. In particular, since a problem occurs when a large amount of powder is gas-treated, it is preferable to constantly flow and agitate the powder using a fluidized bed or the like. In addition, since the element intrusion reaction is diffusion-controlled, a powder having a uniform concentration distribution can be obtained more quickly as the particle size of the powder is smaller. However, if the particle size is too small, a stable flow becomes impossible, so there is a limit naturally, and a particle size of 10 μm to several 100 μm is appropriate.
母相の分解反応があるために、400℃よりも低い温度、好ましくは350℃よりも低い温度、より好ましくは300℃よりも低い温度でフッ素化することとなり、加熱による反応速度向上が望めない。また、拡散律速なので、加圧による反応速度向上も望めない。ただし、加圧により分解を抑えて反応温度を多少上げることは考えられる。水素化によりマイクロクラックが入り元素侵入を助けるので、水素ガスとの混合は微細組織形成の意味において効果的である。F原子の拡散速度は、他の水素原子,窒素原子と比較し、著しく遅いため、粉末中のフッ素濃度分布を均一化する目的で、フッ素化処理後に不活性ガス雰囲気下で熱処理をすることが効果的な場合がある。
Since there is a decomposition reaction of the parent phase, fluorination will occur at a temperature lower than 400 ° C., preferably lower than 350 ° C., more preferably lower than 300 ° C., and an increase in reaction rate due to heating cannot be expected. . Moreover, since it is diffusion-controlled, the reaction rate improvement by pressurization cannot be expected. However, it is conceivable to raise the reaction temperature somewhat by suppressing the decomposition by pressurization. Since microcracks enter by hydrogenation and assist in element entry, mixing with hydrogen gas is effective in terms of forming a fine structure. The diffusion rate of F atoms is extremely slow compared to other hydrogen atoms and nitrogen atoms, so heat treatment can be performed in an inert gas atmosphere after fluorination for the purpose of uniformizing the fluorine concentration distribution in the powder. May be effective.
(3)粉砕工程:
保磁力を発現させるためには、元素侵入工程で得られた粗粉末をジェットミル、またはボールミルなどで平均粒径2~3μmまで微粉砕することが好ましい。原理的には、単磁区臨界粒径0.3μm程度まで微粉砕化することが望ましい。微粉砕後の粒径は非常に細かいため、粒子表面を各種の方法で不活性化する処理が必要な場合がある。 (3) Grinding process:
In order to develop a coercive force, the coarse powder obtained in the element intrusion step is preferably finely pulverized to a mean particle size of 2 to 3 μm by a jet mill or a ball mill. In principle, it is desirable to pulverize to a single domain critical particle size of about 0.3 μm. Since the particle size after pulverization is very fine, it may be necessary to inactivate the particle surface by various methods.
保磁力を発現させるためには、元素侵入工程で得られた粗粉末をジェットミル、またはボールミルなどで平均粒径2~3μmまで微粉砕することが好ましい。原理的には、単磁区臨界粒径0.3μm程度まで微粉砕化することが望ましい。微粉砕後の粒径は非常に細かいため、粒子表面を各種の方法で不活性化する処理が必要な場合がある。 (3) Grinding process:
In order to develop a coercive force, the coarse powder obtained in the element intrusion step is preferably finely pulverized to a mean particle size of 2 to 3 μm by a jet mill or a ball mill. In principle, it is desirable to pulverize to a single domain critical particle size of about 0.3 μm. Since the particle size after pulverization is very fine, it may be necessary to inactivate the particle surface by various methods.
ナノコンポジット用磁粉やHDDR磁粉では、微粉砕しなくとも保磁力が発現するが、磁石体として成形するときに粒径が影響することがあり、微粉砕が必要な場合がある。また、磁粉粒径が保磁力の大きさに関係するために、微粉砕及び分級により粒度分布を整えることは保磁力分布を調整することにもつながり、磁粉の性能、及び信頼性を上げる意味において大切である。
The magnetic powder for nanocomposites and HDDR magnetic powder exhibit coercive force without being finely pulverized, but the particle size may be affected when molded as a magnet body, and fine pulverization may be necessary. In addition, since the particle size of the magnetic particles is related to the coercive force, adjusting the particle size distribution by fine pulverization and classification also leads to adjustment of the coercive force distribution, in the sense of increasing the performance and reliability of the magnetic particles. It is important.
5.磁石作製
本発明における一実施形態としては、磁石材料とバインダーとを含む磁石成形品が挙げられる。 5. Magnet Production As an embodiment of the present invention, a magnet molded product including a magnet material and a binder is exemplified.
本発明における一実施形態としては、磁石材料とバインダーとを含む磁石成形品が挙げられる。 5. Magnet Production As an embodiment of the present invention, a magnet molded product including a magnet material and a binder is exemplified.
(1)バインダー:
磁粉を固めるためのバインダーとしては無機バインバーや有機バインダーがあり、例えば、低融点金属または樹脂を使うことができる。樹脂には、熱硬化性樹脂と熱可塑性樹脂とがある。熱硬化性樹脂としては、EP(エポキシ)樹脂が利用でき、また熱可塑性樹脂としてはPA(ポリアミド,ナイロン)樹脂,PPS(ポリフェニレンサルファイド)樹脂,エラストマーとしてNBR(アクリロニトリルブタジエンゴム),CPE(塩素化ポリエチレン)樹脂やEVA(エチレンビニルアセテート)樹脂などが利用できる。また、無機化合物で固めることもでき、SiO2前駆体の溶液であるCH3O-(Si(CH3O)2-O)m-CH3(mは3~5、平均は4),水,脱水メチルアルコール、及びジラウリン酸ジブチル錫を混合し、含浸させ固化する方法も利用できる。 (1) Binder:
Examples of the binder for hardening the magnetic powder include an inorganic binder and an organic binder. For example, a low melting point metal or a resin can be used. The resin includes a thermosetting resin and a thermoplastic resin. EP (epoxy) resin can be used as the thermosetting resin, PA (polyamide, nylon) resin, PPS (polyphenylene sulfide) resin as thermoplastic resin, NBR (acrylonitrile butadiene rubber), CPE (chlorinated) as elastomer. Polyethylene) resin and EVA (ethylene vinyl acetate) resin can be used. It can also be hardened with an inorganic compound, and is a solution of SiO 2 precursor, CH 3 O— (Si (CH 3 O) 2 —O) m —CH 3 (m is 3 to 5, average is 4), water , Dehydrated methyl alcohol and dibutyltin dilaurate can be mixed, impregnated and solidified.
磁粉を固めるためのバインダーとしては無機バインバーや有機バインダーがあり、例えば、低融点金属または樹脂を使うことができる。樹脂には、熱硬化性樹脂と熱可塑性樹脂とがある。熱硬化性樹脂としては、EP(エポキシ)樹脂が利用でき、また熱可塑性樹脂としてはPA(ポリアミド,ナイロン)樹脂,PPS(ポリフェニレンサルファイド)樹脂,エラストマーとしてNBR(アクリロニトリルブタジエンゴム),CPE(塩素化ポリエチレン)樹脂やEVA(エチレンビニルアセテート)樹脂などが利用できる。また、無機化合物で固めることもでき、SiO2前駆体の溶液であるCH3O-(Si(CH3O)2-O)m-CH3(mは3~5、平均は4),水,脱水メチルアルコール、及びジラウリン酸ジブチル錫を混合し、含浸させ固化する方法も利用できる。 (1) Binder:
Examples of the binder for hardening the magnetic powder include an inorganic binder and an organic binder. For example, a low melting point metal or a resin can be used. The resin includes a thermosetting resin and a thermoplastic resin. EP (epoxy) resin can be used as the thermosetting resin, PA (polyamide, nylon) resin, PPS (polyphenylene sulfide) resin as thermoplastic resin, NBR (acrylonitrile butadiene rubber), CPE (chlorinated) as elastomer. Polyethylene) resin and EVA (ethylene vinyl acetate) resin can be used. It can also be hardened with an inorganic compound, and is a solution of SiO 2 precursor, CH 3 O— (Si (CH 3 O) 2 —O) m —CH 3 (m is 3 to 5, average is 4), water , Dehydrated methyl alcohol and dibutyltin dilaurate can be mixed, impregnated and solidified.
(2)成形方法:
等方性磁粉を用いてボンド磁石を製造する場合には、いかにして生産性良く密度を高められるかが重要な点である。磁粉の着磁特性にもよるが、成形体ができれば任意の着磁が原理的に可能であり、必要な着磁パターンを実現することができる。 (2) Molding method:
When manufacturing a bonded magnet using isotropic magnetic powder, how to increase the density with high productivity is an important point. Although it depends on the magnetization characteristics of the magnetic powder, any magnetization is possible in principle as long as a molded body is formed, and a necessary magnetization pattern can be realized.
等方性磁粉を用いてボンド磁石を製造する場合には、いかにして生産性良く密度を高められるかが重要な点である。磁粉の着磁特性にもよるが、成形体ができれば任意の着磁が原理的に可能であり、必要な着磁パターンを実現することができる。 (2) Molding method:
When manufacturing a bonded magnet using isotropic magnetic powder, how to increase the density with high productivity is an important point. Although it depends on the magnetization characteristics of the magnetic powder, any magnetization is possible in principle as long as a molded body is formed, and a necessary magnetization pattern can be realized.
異方性磁粉を用いてボンド磁石を製造する際に問題になるのは、磁粉の配向である。成形時に粒子の結晶軸を目的とする方向に配向させ、かつ等方性磁石と同様に、密度を高めることが重要である。
When manufacturing a bonded magnet using anisotropic magnetic powder, the problem is the orientation of the magnetic powder. It is important to orient the crystal axes of the particles in the desired direction during molding and to increase the density as in the case of an isotropic magnet.
磁化反転機構は、核発生型とピンニング型とに大別される。前者の場合は、結晶粒径が小さいほど保磁力が向上し、後者の場合は、ピンニングサイトの形状や数により保磁力が決定する。本発明の磁石材料は、作製方法により両方の磁化反転機構を有することが期待される。急冷によって得られる数μmの結晶組織の場合は核発生型、また液体超急冷によって得られる数10~数100nmの結晶組織の場合はピンニング型によって、保磁力が主として決定されると考えられる。磁粉が形状異方性を有する場合には、成形する際の磁粉の向きが保磁力を増加させる上では重要である。一般には、反磁場係数の小さい(パーミアンス係数の大きい)方向を着磁方向となるように成形することが望ましい。
The magnetization reversal mechanism is roughly divided into a nucleation type and a pinning type. In the former case, the smaller the crystal grain size, the better the coercive force. In the latter case, the coercive force is determined by the shape and number of pinning sites. The magnet material of the present invention is expected to have both magnetization reversal mechanisms depending on the production method. It is considered that the coercive force is mainly determined by the nucleation type in the case of a crystal structure of several μm obtained by rapid cooling, and by the pinning type in the case of a crystal structure of several tens to several hundreds of nm obtained by liquid superquenching. When the magnetic powder has shape anisotropy, the direction of the magnetic powder during molding is important for increasing the coercive force. In general, it is desirable to form a direction in which the demagnetizing factor is small (the permeance factor is large) as the magnetization direction.
(3)製造工程:
圧縮成形と射出成形がある。圧縮成形では、磁粉の密度を高めることができるため、高いエネルギー積を実現できる。例えば、原料となる強磁性フッ素化合物のボンド磁石用磁粉とEP樹脂を添加剤と一緒に混練してコンパウンドとし、それを金型に投入してプレス成型する。その後、加熱硬化させた上で、余分な粉末を洗浄して落として表面コートをする。コンパウンド製造時の重要な要素は、粉末粒子の選択,粉末粒子の表面処理,樹脂の選択,混練条件の選択などである。粒子径の分布を最適化することで密度を高めることが可能である。また、密度を高めるために液状樹脂を使って磁粉間の滑り性を高めることは効果的である。異方性磁粉を使用する場合には、磁場印加による磁粉の配向が追加される。使用する樹脂の種類により配向度は異なり、磁場印加時に個々の磁粉がバインダーの粘性に打ち勝って自由に動けることが重要である。 (3) Manufacturing process:
There are compression molding and injection molding. In compression molding, since the density of magnetic powder can be increased, a high energy product can be realized. For example, a magnetic material for a bond magnet of a ferromagnetic fluorine compound as a raw material and an EP resin are kneaded together with an additive to form a compound, which is put into a mold and press-molded. Thereafter, after heat-curing, the excess powder is washed and dropped to coat the surface. Important factors during compound production are selection of powder particles, surface treatment of powder particles, selection of resin, selection of kneading conditions, and the like. It is possible to increase the density by optimizing the particle size distribution. In order to increase the density, it is effective to increase the slipping property between the magnetic particles by using a liquid resin. When using anisotropic magnetic powder, the orientation of the magnetic powder by applying a magnetic field is added. The degree of orientation varies depending on the type of resin used, and it is important that each magnetic powder can move freely overcoming the viscosity of the binder when a magnetic field is applied.
圧縮成形と射出成形がある。圧縮成形では、磁粉の密度を高めることができるため、高いエネルギー積を実現できる。例えば、原料となる強磁性フッ素化合物のボンド磁石用磁粉とEP樹脂を添加剤と一緒に混練してコンパウンドとし、それを金型に投入してプレス成型する。その後、加熱硬化させた上で、余分な粉末を洗浄して落として表面コートをする。コンパウンド製造時の重要な要素は、粉末粒子の選択,粉末粒子の表面処理,樹脂の選択,混練条件の選択などである。粒子径の分布を最適化することで密度を高めることが可能である。また、密度を高めるために液状樹脂を使って磁粉間の滑り性を高めることは効果的である。異方性磁粉を使用する場合には、磁場印加による磁粉の配向が追加される。使用する樹脂の種類により配向度は異なり、磁場印加時に個々の磁粉がバインダーの粘性に打ち勝って自由に動けることが重要である。 (3) Manufacturing process:
There are compression molding and injection molding. In compression molding, since the density of magnetic powder can be increased, a high energy product can be realized. For example, a magnetic material for a bond magnet of a ferromagnetic fluorine compound as a raw material and an EP resin are kneaded together with an additive to form a compound, which is put into a mold and press-molded. Thereafter, after heat-curing, the excess powder is washed and dropped to coat the surface. Important factors during compound production are selection of powder particles, surface treatment of powder particles, selection of resin, selection of kneading conditions, and the like. It is possible to increase the density by optimizing the particle size distribution. In order to increase the density, it is effective to increase the slipping property between the magnetic particles by using a liquid resin. When using anisotropic magnetic powder, the orientation of the magnetic powder by applying a magnetic field is added. The degree of orientation varies depending on the type of resin used, and it is important that each magnetic powder can move freely overcoming the viscosity of the binder when a magnetic field is applied.
射出成形では、複雑な形状のものを後加工なしで成形することができるという特徴がある。バインダーとしてはPA樹脂やPPS樹脂などが用いられる。例えば、原料となる強磁性フッ素化合物のボンド磁粉とPA樹脂またはPPS樹脂とを添加剤と一緒にニーダで混練してペレット状にコンパウンドとする。このコンパウンドを射出成形機に投入して、シリンダー内で加熱溶融させた上で、金型内に射出して成形する。樹脂の粘度調整が必要である。異方性磁粉を使用する場合には、金型に必要な磁気回路を構成しておくことで磁粉の配向が可能となる。高性能の異方性射出成形磁石を製造するためには、溶融したコンパウンドを金型に射出した時に十分配向させる必要がある。
Injection molding is characterized by the ability to form complex shapes without post-processing. As the binder, PA resin or PPS resin is used. For example, a ferromagnetic fluorine compound bond magnetic powder as a raw material and a PA resin or PPS resin are kneaded together with an additive with a kneader to form a compound in a pellet form. This compound is put into an injection molding machine, heated and melted in a cylinder, and then injected into a mold for molding. It is necessary to adjust the viscosity of the resin. When using anisotropic magnetic powder, the magnetic powder can be oriented by forming a magnetic circuit necessary for the mold. In order to produce a high-performance anisotropic injection-molded magnet, it is necessary to sufficiently orient the molten compound when it is injected into the mold.
6.回転機
本発明における一実施形態としては、磁石材料を含む回転子を有する回転機が挙げられる。例えば、PC周辺機器としては、スピンドルモータ(HDD用,CD-ROM/DVD用,FDD用)やステッピングモータ(CD-ROM/DVD用のピックアップ,FDD用のヘッド駆動)が挙げられる。OAとしては、ファクシミリ,コピー,スキャナ,プリンタなどが挙げられる。自動車としては、燃料ポンプ,エアバックセンサ,ABSセンサ,計器,位置制御モータ,点火装置などが挙げられる。HDDやDVDを搭載したPCゲーム機やインターネットやケーブルテレビからデジタルデータをダウンロードして使う装置であるTVセットボックスも挙げられる。家電としては、携帯電話,デジタルカメラ,ビデオカメラ,MP3プレーヤ,PDA,ステレオなどが挙げられる。その他にも、エアコン,掃除機,電動工具などが挙げられる。 6). Rotating machine One embodiment of the present invention includes a rotating machine having a rotor containing a magnet material. For example, examples of the PC peripheral device include a spindle motor (for HDD, CD-ROM / DVD, and FDD) and a stepping motor (CD-ROM / DVD pickup, FDD head drive). Examples of the OA include a facsimile, a copy, a scanner, and a printer. Examples of the automobile include a fuel pump, an airbag sensor, an ABS sensor, an instrument, a position control motor, and an ignition device. There are also PC game machines equipped with HDDs and DVDs, and TV set boxes that are devices that download and use digital data from the Internet or cable TV. Examples of home appliances include mobile phones, digital cameras, video cameras, MP3 players, PDAs, stereos, and the like. Other examples include air conditioners, vacuum cleaners, and power tools.
本発明における一実施形態としては、磁石材料を含む回転子を有する回転機が挙げられる。例えば、PC周辺機器としては、スピンドルモータ(HDD用,CD-ROM/DVD用,FDD用)やステッピングモータ(CD-ROM/DVD用のピックアップ,FDD用のヘッド駆動)が挙げられる。OAとしては、ファクシミリ,コピー,スキャナ,プリンタなどが挙げられる。自動車としては、燃料ポンプ,エアバックセンサ,ABSセンサ,計器,位置制御モータ,点火装置などが挙げられる。HDDやDVDを搭載したPCゲーム機やインターネットやケーブルテレビからデジタルデータをダウンロードして使う装置であるTVセットボックスも挙げられる。家電としては、携帯電話,デジタルカメラ,ビデオカメラ,MP3プレーヤ,PDA,ステレオなどが挙げられる。その他にも、エアコン,掃除機,電動工具などが挙げられる。 6). Rotating machine One embodiment of the present invention includes a rotating machine having a rotor containing a magnet material. For example, examples of the PC peripheral device include a spindle motor (for HDD, CD-ROM / DVD, and FDD) and a stepping motor (CD-ROM / DVD pickup, FDD head drive). Examples of the OA include a facsimile, a copy, a scanner, and a printer. Examples of the automobile include a fuel pump, an airbag sensor, an ABS sensor, an instrument, a position control motor, and an ignition device. There are also PC game machines equipped with HDDs and DVDs, and TV set boxes that are devices that download and use digital data from the Internet or cable TV. Examples of home appliances include mobile phones, digital cameras, video cameras, MP3 players, PDAs, stereos, and the like. Other examples include air conditioners, vacuum cleaners, and power tools.
また、本発明の磁石材料は、大きな磁気体積効果を有しているため、磁性体に圧力を加えるとその磁化の強さが変化するビラリ効果(Villari effect)が期待される。広義の意
味で磁歪現象に属し、工業的にはセンサやアクチュエータに利用できる。 In addition, since the magnet material of the present invention has a large magnetovolume effect, a Villari effect is expected in which the strength of magnetization changes when a pressure is applied to the magnetic material. It belongs to the magnetostriction phenomenon in a broad sense and can be used industrially for sensors and actuators.
味で磁歪現象に属し、工業的にはセンサやアクチュエータに利用できる。 In addition, since the magnet material of the present invention has a large magnetovolume effect, a Villari effect is expected in which the strength of magnetization changes when a pressure is applied to the magnetic material. It belongs to the magnetostriction phenomenon in a broad sense and can be used industrially for sensors and actuators.
7.塩素化
本発明には、水素化,窒素化,炭素化またはフッ素化と共に塩素化を行う方法も含まれる。本発明の特徴は、F原子の侵入による結晶格子体積の増加に伴う幾何学的な効果を原因として磁性の改質が生じることである。そのため、F原子ではなく同族であるCl原子でも同様の効果が期待できる。 7. Chlorination The present invention also includes a method of chlorination along with hydrogenation, nitrogenation, carbonization or fluorination. A feature of the present invention is that the magnetic modification occurs due to the geometric effect accompanying the increase of the crystal lattice volume due to the penetration of F atoms. Therefore, the same effect can be expected even with Cl atoms belonging to the same group instead of F atoms.
本発明には、水素化,窒素化,炭素化またはフッ素化と共に塩素化を行う方法も含まれる。本発明の特徴は、F原子の侵入による結晶格子体積の増加に伴う幾何学的な効果を原因として磁性の改質が生じることである。そのため、F原子ではなく同族であるCl原子でも同様の効果が期待できる。 7. Chlorination The present invention also includes a method of chlorination along with hydrogenation, nitrogenation, carbonization or fluorination. A feature of the present invention is that the magnetic modification occurs due to the geometric effect accompanying the increase of the crystal lattice volume due to the penetration of F atoms. Therefore, the same effect can be expected even with Cl atoms belonging to the same group instead of F atoms.
塩素化反応は以下の実施例1~3に記載する方法と同様に行うことができる。ただし、塩化ガスとして、塩化アンモニウム(NH4Cl、338℃で分解)の熱分解物,三塩化窒素,三塩化ホウ素,塩化水素,塩素などが使用される。当然ながら、これらを混合して使用したり、同時に使用してもよい。例えば、塩化アンモニウムを用いた塩素化では、300℃以上で実施することが好ましく、分解温度338℃以上で実施することが特に好ましい。塩化アンモニウム以外の三塩化窒素,三塩化ホウ素,塩化水素、または塩素を使用する場合はこの限りでない。
The chlorination reaction can be carried out in the same manner as described in Examples 1 to 3 below. However, ammonium chloride (NH 4 Cl, decomposed at 338 ° C.) thermal decomposition product, nitrogen trichloride, boron trichloride, hydrogen chloride, chlorine or the like is used as the chloride gas. Of course, these may be mixed and used simultaneously. For example, chlorination using ammonium chloride is preferably carried out at 300 ° C. or higher, particularly preferably at a decomposition temperature of 338 ° C. or higher. This does not apply when using nitrogen trichloride, boron trichloride, hydrogen chloride, or chlorine other than ammonium chloride.
水素原子,窒素原子,炭素原子またはフッ素原子と、塩素原子とが結晶格子内の侵入位置に適当な占有率で共存していればよいため、これらの元素の導入方法は特に限定されない。
Since a hydrogen atom, a nitrogen atom, a carbon atom, a fluorine atom, and a chlorine atom need only coexist at an intrusion position in the crystal lattice with an appropriate occupation ratio, the method for introducing these elements is not particularly limited.
〔実施例〕
以下、実施例を用いて本発明をより詳細に説明するが、本発明の技術的範囲はこれにより限定されるものではない。 〔Example〕
EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, the technical scope of this invention is not limited by this.
以下、実施例を用いて本発明をより詳細に説明するが、本発明の技術的範囲はこれにより限定されるものではない。 〔Example〕
EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, the technical scope of this invention is not limited by this.
実施例1:F原子及びH原子を含有する合金
R(SmまたはNd)-Fe系主相合金は、希土類の蒸発を加味し、FeにSmまたはNdを化学量論比よりも多目に混合して真空あるいは不活性ガス中または還元ガス雰囲気中で溶解し組成を均一化した。相形成のための熱処理後、急冷することにより作製した。Sm2Fe17,Sm3Fe28Ti、及びNdFe11TiはFeの包晶反応によって析出するため、得られる合金には微量のα-Feの混入が避け難い。得られたSm2Fe17のインゴットは、平均粒径が10μm以下となるように不活性ガス中でジェットミルを使用し粉砕した。ジェットミル粉砕により作製したSm2Fe17,Sm3Fe28Ti、及びNdFe11Tiの各磁粉に対し、フッ化アンモニウム(NH4F、水への溶解度45.3mg/100ml(25℃))及び酸性フッ化アンモニウム(NH4F・HF、水への溶解度77.7g/100ml(25℃))の熱分解・昇華により発生するフッ化水素ガスを使用してフッ化水素ガス処理を実施した。 Example 1: Alloy containing F and H atoms The R (Sm or Nd) -Fe main phase alloy takes into account the evaporation of rare earths and mixes Fe with Sm or Nd more frequently than the stoichiometric ratio. Then, it was dissolved in a vacuum, an inert gas or a reducing gas atmosphere to make the composition uniform. It was prepared by quenching after heat treatment for phase formation. Since Sm 2 Fe 17 , Sm 3 Fe 28 Ti, and NdFe 11 Ti are precipitated by the peritectic reaction of Fe, it is difficult to avoid a trace amount of α-Fe in the obtained alloy. The obtained ingot of Sm 2 Fe 17 was pulverized using a jet mill in an inert gas so that the average particle diameter was 10 μm or less. Ammonium fluoride (NH 4 F, solubility in water 45.3 mg / 100 ml (25 ° C.)) and Sm 2 Fe 17 , Sm 3 Fe 28 Ti and NdFe 11 Ti magnetic powders prepared by jet milling Hydrogen fluoride gas treatment was carried out using hydrogen fluoride gas generated by thermal decomposition and sublimation of acidic ammonium fluoride (NH 4 F · HF, solubility in water 77.7 g / 100 ml (25 ° C.)).
R(SmまたはNd)-Fe系主相合金は、希土類の蒸発を加味し、FeにSmまたはNdを化学量論比よりも多目に混合して真空あるいは不活性ガス中または還元ガス雰囲気中で溶解し組成を均一化した。相形成のための熱処理後、急冷することにより作製した。Sm2Fe17,Sm3Fe28Ti、及びNdFe11TiはFeの包晶反応によって析出するため、得られる合金には微量のα-Feの混入が避け難い。得られたSm2Fe17のインゴットは、平均粒径が10μm以下となるように不活性ガス中でジェットミルを使用し粉砕した。ジェットミル粉砕により作製したSm2Fe17,Sm3Fe28Ti、及びNdFe11Tiの各磁粉に対し、フッ化アンモニウム(NH4F、水への溶解度45.3mg/100ml(25℃))及び酸性フッ化アンモニウム(NH4F・HF、水への溶解度77.7g/100ml(25℃))の熱分解・昇華により発生するフッ化水素ガスを使用してフッ化水素ガス処理を実施した。 Example 1: Alloy containing F and H atoms The R (Sm or Nd) -Fe main phase alloy takes into account the evaporation of rare earths and mixes Fe with Sm or Nd more frequently than the stoichiometric ratio. Then, it was dissolved in a vacuum, an inert gas or a reducing gas atmosphere to make the composition uniform. It was prepared by quenching after heat treatment for phase formation. Since Sm 2 Fe 17 , Sm 3 Fe 28 Ti, and NdFe 11 Ti are precipitated by the peritectic reaction of Fe, it is difficult to avoid a trace amount of α-Fe in the obtained alloy. The obtained ingot of Sm 2 Fe 17 was pulverized using a jet mill in an inert gas so that the average particle diameter was 10 μm or less. Ammonium fluoride (NH 4 F, solubility in water 45.3 mg / 100 ml (25 ° C.)) and Sm 2 Fe 17 , Sm 3 Fe 28 Ti and NdFe 11 Ti magnetic powders prepared by jet milling Hydrogen fluoride gas treatment was carried out using hydrogen fluoride gas generated by thermal decomposition and sublimation of acidic ammonium fluoride (NH 4 F · HF, solubility in water 77.7 g / 100 ml (25 ° C.)).
フッ化水素ガス処理は管状炉によるガスフロー形式で実施した。発生する余剰ガスを吸収するために、反応装置の下流にはトラップ機構を設けた。グラッシーカーボン(Glass carbon、GC)ボート上に試料を薄く広げ配置した。ただし、試料容器の材質は炭素以外にも白金やニッケルなどでも構わない。上流と下流には、フッ化アンモニウム粉を入れたGCボートを配置した。フッ化アンモニウムの仕込み量は、反応空間の大きさ,流すガスの流量,熱処理温度,熱処理時間による。今回は、半径28mm,長さ1200mmの石英管を使用し、磁粉20gに対し、フッ化アンモニウム、及び酸性フッ化アンモニウムを上流にそれぞれ10g、下流にそれぞれ10g、配置した。ロータリーポンプにより真空排気した後、Arを200ml/min.で流し、電気炉を加熱した。150℃,200℃,250℃、及び300℃において反応時間が24時間となるように熱処理を実施した。
Hydrogen fluoride gas treatment was performed in a gas flow format using a tubular furnace. In order to absorb the generated surplus gas, a trap mechanism was provided downstream of the reactor. The sample was spread thinly on a glassy carbon (GC) boat. However, the material of the sample container may be platinum or nickel other than carbon. A GC boat containing ammonium fluoride powder was disposed upstream and downstream. The amount of ammonium fluoride charged depends on the size of the reaction space, the gas flow rate, the heat treatment temperature, and the heat treatment time. This time, a quartz tube having a radius of 28 mm and a length of 1200 mm was used, and 10 g of ammonium fluoride and ammonium acid fluoride were arranged upstream and 10 g respectively downstream of the magnetic powder 20 g. After evacuating with a rotary pump, Ar was flowed at 200 ml / min. To heat the electric furnace. Heat treatment was performed at 150 ° C., 200 ° C., 250 ° C., and 300 ° C. so that the reaction time was 24 hours.
熱処理温度の選定では、Sm2Fe17の分解・酸化反応が比較的小さい低温側を選定し、望ましくは300℃よりも低温である。また、熱処理時間の選定では、水素化、及びフッ素化が同時に進行するため短時間でも十分な拡散が期待できる。ただし、磁粉サイズ,結晶粒径,磁粉の表面状態,組織形状などに大きく依存する。フッ化アンモニウム、及び酸性フッ化アンモニウムと磁粉を混合してGCボート上に配置する方が、水素化及びフッ素化の促進が期待されるが、フッ化水素発生源と磁粉とが直に接することで、強すぎる酸化還元拡散反応が生じ、磁粉の外周部は希土類フッ化物,希土類酸フッ化物,鉄フッ化物,鉄などに分解する。使用する磁粉の粒径などにより適宜選択する必要がある。
In selecting the heat treatment temperature, the low temperature side where the decomposition / oxidation reaction of Sm 2 Fe 17 is relatively small is selected, and the temperature is preferably lower than 300 ° C. Further, in the selection of the heat treatment time, sufficient diffusion can be expected even in a short time because hydrogenation and fluorination proceed simultaneously. However, it greatly depends on the magnetic powder size, the crystal grain size, the surface state of the magnetic powder, the structure shape, and the like. It is expected that hydrogen fluoride and fluorination will be accelerated by mixing ammonium fluoride and acidic ammonium fluoride and magnetic powder and placing them on the GC boat, but the hydrogen fluoride generation source and magnetic powder are in direct contact with each other. Thus, an excessively strong redox diffusion reaction occurs, and the outer periphery of the magnetic powder is decomposed into rare earth fluoride, rare earth oxyfluoride, iron fluoride, iron, and the like. It is necessary to select appropriately depending on the particle size of the magnetic powder to be used.
混合の際は未反応生成物を除去する目的で、熱処理の最後に真空置換を実施しても構わない。試料は未反応物が付着している可能性があるため、ポリエチレン容器に入れ真空梱包状態で保存した。ただし、水素化、及びフッ素化した磁粉は室温においては極めて安定であるため、未反応物の付着量が問題にならない場合は、ガラス瓶でも構わない。
When mixing, vacuum replacement may be performed at the end of the heat treatment for the purpose of removing unreacted products. The sample was stored in a vacuum container in a polyethylene container because unreacted material may be attached. However, since hydrogenated and fluorinated magnetic powders are extremely stable at room temperature, glass bottles may be used if the amount of unreacted material does not matter.
本方法は、固気反応かつ低温反応であるため、反応の不均一性が問題となる。そのため、流動床などを導入し、満遍なく反応が進行するようにすることが望ましい。
Since this method is a solid-gas reaction and a low-temperature reaction, non-uniformity of the reaction becomes a problem. Therefore, it is desirable to introduce a fluidized bed or the like so that the reaction proceeds evenly.
以下では、代表的なSm2Fe17に対する分析結果を示す。Sm3Fe28Ti、及びNdFe11Tiにおいても概ね似た結果を得た。
The following shows the analytical results for representative Sm 2 Fe 17. Similar results were obtained with Sm 3 Fe 28 Ti and NdFe 11 Ti.
図1は、(a)Sm2Fe17磁粉,(b)150℃24h熱処理磁粉,(c)200℃24h熱処理磁粉,(d)250℃24h熱処理磁粉,(e)300℃24h熱処理磁粉、及び(f)350℃24h熱処理磁粉の室温における粉末X線回折パターンをそれぞれ示す。熱処理温度の違いによる生成物の構造変化を観測するため、粉末X線回折を実施した。回折ピークはSmFe3を○、Feを△、FeF2(ルチル型、空間群P42/mnm)を▽、SmF3(β-YF3型、空間群Pnma)とSmOF(歪CaF2型、空間群R-3m)を□、及びSm2Fe17を無印でそれぞれ示す。ただし、サマリウム酸フッ化物は、様々な組成比・構造の相が知られており、それらの回折ピークの位置が散漫回折の中に位置し区別が困難であることから、SmOFで代表した。(a)Sm2Fe17磁粉は、主相のSm2Fe17以外にも微量のFe及びSmFe3に対応する回折ピークを観測した。Sm2Fe17はFeと液相の包晶反応によって生成し、かつFeの融点と包晶温度の差が大きいため、Fe初相が凝固終了後も残存する。高温熱処理により相成長させているが、微量の異相生成は避け難い。(b)150℃24h熱処理磁粉、及び(c)200℃24h熱処理磁粉では、FeF2の生成を観測した。(d)250℃24h熱処理磁粉,(e)300℃24h熱処理磁粉、及び(f)350℃24h熱処理磁粉では、FeF2の回折ピークは、散漫回折に埋もれ明瞭に観測することができず、ピーク分割解析を実施しても確認できなかった。さらに、熱処理温度の上昇に伴い25度付近から35度付近、及び45度付近の各散漫回折が大きくなるのを観測した。低角側はSmF3,SmOFなど、また高角側はFeの散漫回折にそれぞれ対応する。150℃よりも高温の酸化雰囲気中での熱処理により、Sm2Fe17の一部が分解しSm及びFeが微細結晶粒として析出し、さらにそれらの一部が酸化及びフッ素化したと推定される。このように、異相として少なくとも希土類フッ化物,希土類酸フッ化物,鉄、及び鉄フッ化物が発生する。散漫回折の反値幅をScherrer法により解析した結果、平均的な析出結晶の大きさは5nm程度であり、熱処理温度依存性はほとんど観測できなかった。
FIG. 1 shows (a) Sm 2 Fe 17 magnetic powder, (b) 150 ° C. 24 h heat treated magnetic powder, (c) 200 ° C. 24 h heat treated magnetic powder, (d) 250 ° C. 24 h heat treated magnetic powder, (e) 300 ° C. 24 h heat treated magnetic powder, (F) The powder X-ray diffraction pattern at room temperature of the heat-treated magnetic powder at 350 ° C. for 24 hours is shown. In order to observe the structural change of the product due to the difference in heat treatment temperature, powder X-ray diffraction was performed. The diffraction peaks are SmFe 3 for ◯, Fe for △, FeF 2 (rutile type, space group P4 2 / mnm) ▽, SmF 3 (β-YF 3 type, space group Pnma) and SmOF (strained CaF 2 type, space). Group R-3m) is indicated by □, and Sm 2 Fe 17 is indicated by no mark. However, samarium oxyfluoride is represented by SmOF because phases of various composition ratios and structures are known, and their diffraction peaks are located in diffuse diffraction and are difficult to distinguish. (A) In Sm 2 Fe 17 magnetic powder, diffraction peaks corresponding to a small amount of Fe and SmFe 3 were observed in addition to Sm 2 Fe 17 of the main phase. Sm 2 Fe 17 is produced by the peritectic reaction of Fe and liquid phase, and the difference between the melting point and the peritectic temperature of Fe is large, so the Fe initial phase remains even after the solidification. Although phase growth is performed by high-temperature heat treatment, it is difficult to avoid a small amount of foreign phase formation. The formation of FeF 2 was observed in (b) 150 ° C. 24 h heat treated magnetic powder and (c) 200 ° C. 24 h heat treated magnetic powder. In (d) 250 ° C. 24 h heat treated magnetic powder, (e) 300 ° C. 24 h heat treated magnetic powder, and (f) 350 ° C. 24 h heat treated magnetic powder, the diffraction peak of FeF 2 is buried in diffuse diffraction and cannot be clearly observed. It was not able to be confirmed even if division analysis was carried out. Furthermore, it was observed that the diffuse diffraction increases from around 25 degrees to around 35 degrees and around 45 degrees as the heat treatment temperature increases. The low angle side corresponds to SmF 3 , SmOF, etc., and the high angle side corresponds to the diffuse diffraction of Fe. By heat treatment in an oxidizing atmosphere higher than 150 ° C., it is estimated that a part of Sm 2 Fe 17 was decomposed and Sm and Fe were precipitated as fine crystal grains, and a part of them was oxidized and fluorinated. . Thus, at least rare earth fluoride, rare earth oxyfluoride, iron, and iron fluoride are generated as heterogeneous phases. As a result of analyzing the reciprocal width of the diffuse diffraction by the Scherrer method, the average size of the precipitated crystals was about 5 nm, and the heat treatment temperature dependence was hardly observed.
図2は、電子線マイクロアナライザ(Electron probe micro analyzer、EPMA)により測定した250℃24h熱処理磁粉の結晶粒断面における(a)2次電子像,(b)C,(c)N,(d)O,(e)F,(f)Fe,(g)Pr、及び(h)Smの元素濃度分布像をそれぞれ示す。ただし、元素濃度は重量百分率(wt%)で表示している。Sm2Fe17への侵入元素として知られる(b)C原子、及び(c)N原子は、EPMAの分解能(C原子:0.0x-1wt%、N原子:~1wt%)では結晶粒内において熱処理前後で同じ濃度であり、熱処理によるC原子,N原子の侵入は確認できなかった。(d)O原子,(e)F原子,(f)Fe原子、及び(h)Sm原子は、熱処理することによって結晶粒内で非一様な分布を示すことを観測した。粉末X線回折における散漫回折の半値幅から5nm程度の微細な結晶粒としてSmF3,SmOF、及びFeの存在を観測しており(図1参照)、EPMAの観測スケールではそれらの相は混相として同じ領域に観測される。特に、OとFの濃度分布には磁粉外周部において相関のある領域が確認でき、O濃度の高い領域ではF濃度も高い傾向を示す。磁粉外周部は酸化しやすく、酸化した相が熱処理によりフッ素化しSmF3,SmOFなどが生成すると推定される。また、Sm2Fe17磁粉よりも250℃24h熱処理磁粉の方が磁粉外周部におけるO濃度が高くなっていることを観測しており、酸化は熱処理時に主として生じると考えられる。磁粉表面に付着した水分の影響が示唆される。各元素の濃度比を考慮すると、(e)Fの濃度分布像において青い領域がSm2Fe17の対称性を有する相に対応すると推定される。ただし、FKαではFeLαの裾に被るため、Fの濃度の低い領域でFeの元素濃度分布の影響を被る(図3参照)。
FIG. 2 shows (a) secondary electron image, (b) C, (c) N, (d) in a crystal grain cross section of 250 ° C. 24 h heat treated magnetic powder measured by an electron probe micro analyzer (EPMA). Element concentration distribution images of O, (e) F, (f) Fe, (g) Pr, and (h) Sm are shown, respectively. However, the element concentration is expressed in weight percentage (wt%). (B) C atoms and (c) N atoms, which are known as intruding elements into Sm 2 Fe 17 , are within the crystal grains at the resolution of EPMA (C atoms: 0.0x-1 wt%, N atoms: ˜1 wt%). In FIG. 5, the concentration was the same before and after the heat treatment, and the penetration of C atoms and N atoms by the heat treatment could not be confirmed. It was observed that (d) O atoms, (e) F atoms, (f) Fe atoms, and (h) Sm atoms show non-uniform distribution within the crystal grains by heat treatment. Presence of SmF 3 , SmOF, and Fe is observed as fine crystal grains of about 5 nm from the half-value width of diffuse diffraction in powder X-ray diffraction (see Fig. 1), and these phases are mixed in the EPMA observation scale. Observed in the same area. In particular, in the O and F concentration distribution, a correlated region can be confirmed in the outer periphery of the magnetic powder, and the F concentration tends to be high in the region where the O concentration is high. It is estimated that the outer periphery of the magnetic powder is easily oxidized, and the oxidized phase is fluorinated by heat treatment to produce SmF 3 , SmOF and the like. Further, it has been observed that the O concentration in the outer periphery of the magnetic powder is higher in the 250 ° C. 24 h heat treated magnetic powder than in the Sm 2 Fe 17 magnetic powder, and oxidation is considered to occur mainly during the heat treatment. The effect of moisture adhering to the magnetic powder surface is suggested. Considering the concentration ratio of each element, (e) it is presumed that the blue region in the F concentration distribution image corresponds to a phase having Sm 2 Fe 17 symmetry. However, since incurred hem of the FK alpha FeL alpha, suffer the effects of element concentration distribution of Fe with low concentrations of F region (see FIG. 3).
図3は、分光結晶(a)LS7A(回折格子),(b)RAP(酸性フタル酸ルビジウム)、及び(c)LS5A(回折格子)を使用し計測した場所A,場所B、及び場所C(図2(a)2次電子像参照)におけるFKα近傍のエネルギースペクトル、及び元素定量結果をそれぞれ示す。ただし、スペクトル形状を左右対称にするため、横軸の単位を波長からエネルギーに変換して表示している。関数近似に際し、エネルギー範囲が狭いため装置の分解能関数の畳み込みを無視し3つのLorentz関数(FKα,FeLα1,FeLα2)により近似した。また、分光結晶であるため(a)では2λを観測している。結果、いずれの分光結晶においてもFeLαのピークの裾がFKαに被ることが判明した。F原子の検出下限は、重量百分率換算で3wt%程度から4wt%程度であることがわかった。Sm2Fe17Fx構造を仮定した場合、x≦2~2.7では検出することができないことになる。場所A,場所B、及び場所Cにおいて標準試料を用い定量しZAF補正した結果、いずれの場所においても元素比はSm:Fe~2:17となっており、また、F原子は場所A、及び場所Bにおいて検出することはできず、場所Cにおいて17at%検出した。電子線ビーム径が1μmであること、かつ金属材料に対する電子線の潜り込み、及び特性X線の脱出深度が2μmから3μm程度であることを考慮すると、場所CではSm2Fe17が分解し、FeF2,SmF3,SmOFなど複数の相が混在していると推定される。
FIG. 3 shows a place A, a place B, and a place C (measured using spectral crystals (a) LS7A (diffraction grating), (b) RAP (rubidium acid phthalate), and (c) LS5A (diffraction grating). energy spectrum near FK alpha in FIGS. 2 (a) see secondary electron image), and elemental quantitative results are shown, respectively. However, in order to make the spectrum shape symmetrical, the unit of the horizontal axis is converted from wavelength to energy and displayed. In the function approximation, since the energy range is narrow, convolution of the resolution function of the apparatus is ignored and approximation is performed by three Lorentz functions (FK α , FeL α1 , FeL α2 ). Further, since it is a spectral crystal, 2λ is observed in (a). Result, the skirt of the peak of FeL alpha in any of analyzing crystal was found to be incurred FK alpha. The lower limit of detection of F atoms was found to be about 3 wt% to about 4 wt% in terms of weight percentage. Assuming the Sm 2 Fe 17 F x structure, it cannot be detected when x ≦ 2 to 2.7. Location A, where B, and the location quantified ZAF correction result using a standard sample in C, the elemental ratio at any location Sm: has a Fe ~ 2:17, also, F atom location A, and Detection was not possible at location B, and 17 at% was detected at location C. Considering that the electron beam beam diameter is 1 μm, the penetration of the electron beam into the metal material, and the escape depth of the characteristic X-ray is about 2 μm to 3 μm, Sm 2 Fe 17 is decomposed at the place C, and FeF 2 , SmF 3 , SmOF, etc. are presumed to be mixed.
以上の結果、Sm2F17へのC原子、及びN原子の侵入はEPMAの検出分解能の範囲では否定できる。
As a result, the penetration of C atoms and N atoms into Sm 2 F 17 can be denied in the range of EPMA detection resolution.
EPMAでは検出できなかったH原子、及びF原子の侵入の有無を検証するため、2通りの質量分析手法を実施した。
In order to verify the presence or absence of H atoms and F atoms that could not be detected by EPMA, two mass spectrometry methods were implemented.
試料全体から発生する元素種の分析から侵入元素を推察するため、昇温脱離ガス分析を実施した。
A temperature-programmed desorption gas analysis was performed to infer invading elements from the analysis of the element species generated from the entire sample.
図4は、(a)Sm2Fe17磁粉、及び(b)250℃24h熱処理磁粉の脱離ガスの温度依存性をそれぞれ示す。使用した薬品、及び脱離ガス量の温度変化を考慮し、各質量電荷比m/zに対応する組成式は、m/z=1はH+、m/z=2はH2
+、m/z=16はO+,CH4,NH2
+、m/z=17はOH+,NH3
+、m/z=18はH2O+,NH4
+、m/z=19はF+、m/z=20はHF+、m/z=28はN2
+、及びm/z=44はN2O+,CO2
+,C3H8
+と推定される。m/z=85はN2F3
+が考えられるが、詳細不明は不明である。(a)は、質量電荷比m/z=1,2,16,17,18,44を有する脱離ガスが100℃付近をピークに300℃付近までの温度領域で発生するのを観測した。磁粉に付着した水分が主として脱離すると推定される。また、約320℃から約500℃の温度領域で、質量電荷比m/z=2を有する脱離ガスが発生するのを観測した。これは、Sm2Fe17Hxは約350℃から約550℃の温度範囲でH原子を放出することが知られており、主相に微量に含まれるH原子によるものと推定される。実際に、購入したSm2Fe17磁粉のキュリー温度は、文献値よりも4℃から12℃程度高いことを確認しており、微量に含まれるH原子の存在を支持する。(b)は、脱理ガスの種類・発生パターンから4つの温度領域に分けることができる。温度領域I(0℃~約120℃)では、質量電荷比m/z=1,2,16,17,18,44を有する脱離ガスが100℃付近をピークに観測した。磁粉に付着した水分の脱離と考えられる。温度領域II(約120℃~約400℃)では、質量電荷比m/z=1,2,16,17,18,19を有する脱離ガスが200℃付近をピークに400℃付近までの温度領域で発生するのを観測した。試料表面に残存しているフッ化水素アンモニウムの熱分解により生じる脱離ガスと推定される。しかし、質量電荷比m/z=19,20を有する脱離ガスは挙動が異なり、210℃から400℃の温度領域で増加することを観測した。Sm2Fe17からF原子が脱離するものと思われるが、残存するフッ化水素アンモニウムの分解のモードが複雑に変化している可能性もある。温度領域III(約400℃~約540℃)では、質量電荷比m/z=2,28を有する脱離ガスが発生しており、フッ化水素アンモニウムの分解により生じたアンモニア成分の分解に関連すると思われる。温度領域IV(約540℃~680℃)では、質量電荷比m/z=19,28,85を有する脱離ガスが増加することを観測した。フッ化水素アンモニウムが分解し発生するガスに関連すると推定されるが、詳細は不明である。
FIG. 4 shows the temperature dependence of the desorption gas of (a) Sm 2 Fe 17 magnetic powder and (b) 250 ° C. 24 h heat-treated magnetic powder, respectively. In consideration of the chemical used and the temperature change of the amount of desorbed gas, the composition formula corresponding to each mass-to-charge ratio m / z is as follows: m / z = 1 is H + , m / z = 2 is H 2 + , m / Z = 16 is O + , CH 4 , NH 2 + , m / z = 17 is OH + , NH 3 + , m / z = 18 is H 2 O + , NH 4 + , m / z = 19 is F + , M / z = 20 is estimated as HF + , m / z = 28 is estimated as N 2 + , and m / z = 44 is estimated as N 2 O + , CO 2 + , C 3 H 8 + . For m / z = 85, N 2 F 3 + is considered, but the details are unknown. In (a), it was observed that a desorbed gas having a mass-to-charge ratio m / z = 1, 2, 16, 17, 18, 44 was generated in a temperature range from about 100 ° C. to about 300 ° C. It is estimated that water adhering to the magnetic powder is mainly desorbed. In addition, it was observed that a desorbed gas having a mass-to-charge ratio m / z = 2 was generated in a temperature range of about 320 ° C. to about 500 ° C. Sm 2 Fe 17 H x is known to release H atoms in a temperature range of about 350 ° C. to about 550 ° C., and is presumed to be due to H atoms contained in a trace amount in the main phase. Actually, it has been confirmed that the Curie temperature of the purchased Sm 2 Fe 17 magnetic powder is about 4 ° C. to 12 ° C. higher than the literature value, and supports the presence of H atoms contained in a trace amount. (B) can be divided into four temperature regions based on the type and generation pattern of the degassing gas. In the temperature region I (0 ° C. to about 120 ° C.), a desorption gas having a mass-to-charge ratio m / z = 1, 2, 16, 17, 18, 44 was observed at a peak around 100 ° C. This is thought to be the detachment of water adhering to the magnetic powder. In the temperature region II (about 120 ° C. to about 400 ° C.), the temperature of the desorbed gas having a mass-to-charge ratio m / z = 1, 2, 16, 17, 18, 19 reaches about 400 ° C. with a peak around 200 ° C. Observed to occur in the region. It is presumed to be a desorbed gas generated by thermal decomposition of ammonium hydrogen fluoride remaining on the sample surface. However, it was observed that the desorbed gas having a mass-to-charge ratio m / z = 19,20 behaves differently and increased in the temperature range from 210 ° C. to 400 ° C. Although it is considered that F atoms are desorbed from Sm 2 Fe 17, there is a possibility that the decomposition mode of the remaining ammonium hydrogen fluoride is complicatedly changed. In temperature region III (about 400 ° C to about 540 ° C), a desorption gas having a mass-to-charge ratio of m / z = 2,28 is generated, which is related to decomposition of the ammonia component generated by decomposition of ammonium hydrogen fluoride. It seems to be. In the temperature region IV (about 540 ° C. to 680 ° C.), it was observed that desorbed gas having a mass-to-charge ratio m / z = 19, 28, 85 increased. Although it is presumed to be related to a gas generated by decomposition of ammonium hydrogen fluoride, details are unknown.
H原子、及びF原子を主に微量かつ局所的な元素濃度分布を分析するため、飛行時間型2次イオン質量分析計(Time-of-flight secondary ion mass spectrometer、TOF-SIMS)を使用した。
A time-of-flight secondary ion mass spectrometer (TOF-SIMS) was used to analyze a trace amount and local element concentration distribution mainly of H atoms and F atoms.
図5は、250℃24h熱処理磁粉の結晶粒断面における(a)総イオン,(b)Fe+,(c)FeH+,(d)FeOH+,(e)Sm+,(f)SmF+,(g)H+,(h)Na+,(i)Al+,(j)Si+、及び(k)Ca+のイオン像をそれぞれ示す。(b)Fe+、及び(e)Sm+のイオン像から、Fe元素とSm元素は不均一な組成分布を示すことを観測した。特に、(b)Fe+と(f)SmF+のイオン像から、Fe原子,Sm原子、及びF原子が結晶粒外周部に多く偏析していることを観測した。(c)FeH+と(d)FeOH+のイオン像の比較から、O元素も結晶粒外周部に多く存在することがわかった。熱処理過程でのSm2Fe17の分解・析出により発生する微細なFe,SmF3、及びSmOFと推定される。さらに、微細な結晶粒ではほとんどがFe,SmF3、及びSmOFとして存在していることがわかった。これらを踏まえると、酸化したSm2Fe17は、熱処理過程でSm2Fe17の対称性を有する構造を維持することができないと考えられる。異相として少なくとも希土類フッ化物,希土類酸フッ化物,鉄、及び鉄フッ化物が発生する。また、磁粉外周部の酸化を抑制できたとしても、HFガスと磁粉との接触により磁粉外周部の分解は避け難い可能性がある。結晶粒中心部では、樹脂部分と比較しバックグラウンド以上の強度で(f)SmF+,(g)H+の各イオンを観測した。つまり、Sm2Fe17の対称性を有する相と想定される領域において、F原子とH原子を検出した。同じ領域で観測される(h)Na+,(i)Al+,(j)Si+、及び(k)Ca+はSm2Fe17磁粉作製時に混入する微量不純物である。また、(j)Si+イオンを磁粉外周部から大量に検出し、フッ素化処理の際に使用した石英管がフッ化水素に侵されフッ化ケイ素ガスとして磁粉に付着したと思われる。
FIG. 5 shows (a) total ions, (b) Fe + , (c) FeH + , (d) FeOH + , (e) Sm + , (f) SmF + , and 250 ° C. for 24 h. (G) Ion images of H + , (h) Na + , (i) Al + , (j) Si + , and (k) Ca + are shown, respectively. From the ion images of (b) Fe + and (e) Sm + , it was observed that the Fe element and the Sm element showed a non-uniform composition distribution. In particular, from the ion images of (b) Fe + and (f) SmF + , it was observed that many Fe atoms, Sm atoms, and F atoms were segregated on the outer periphery of the crystal grains. From the comparison of the ion images of (c) FeH + and (d) FeOH + , it was found that a large amount of O element was also present in the outer periphery of the crystal grains. Presumed to be fine Fe, SmF 3 and SmOF generated by decomposition and precipitation of Sm 2 Fe 17 during the heat treatment. Furthermore, it was found that most of the fine crystal grains existed as Fe, SmF 3 and SmOF. Given these, Sm 2 Fe 17 was oxidized, it would not be able to maintain a structure with symmetry of Sm 2 Fe 17 during the heat treatment. At least rare earth fluoride, rare earth oxyfluoride, iron, and iron fluoride are generated as different phases. Even if the oxidation of the outer periphery of the magnetic powder can be suppressed, it may be difficult to avoid the decomposition of the outer periphery of the magnetic powder due to the contact between the HF gas and the magnetic powder. At the center of the crystal grain, each ion of (f) SmF + and (g) H + was observed at an intensity higher than the background compared to the resin part. That is, F atoms and H atoms were detected in a region assumed to be a phase having symmetry of Sm 2 Fe 17 . (H) Na + , (i) Al + , (j) Si + , and (k) Ca + observed in the same region are trace impurities that are mixed during the production of Sm 2 Fe 17 magnetic powder. Further, (j) a large amount of Si + ions were detected from the outer periphery of the magnetic powder, and it seems that the quartz tube used in the fluorination treatment was attacked by hydrogen fluoride and adhered to the magnetic powder as silicon fluoride gas.
図6は、TOF-SIMSを使用し計測した250℃24h熱処理磁粉の結晶粒断面における(a)総イオン,(b)FeO-,(c)FeO2
-,(d)FeO2H-,(e)H-,(f)C-,(g)O-,(h)OH-,(i)F-,(j)CN-、及び(k)Cl-のイオン像をそれぞれ示す。(e)H-と(g)O-のイオン像に相関があり、H濃度に対応しO濃度も高くなる傾向がある。試料間の比較は参考程度であるが、磁粉周りの樹脂部分と結晶粒内との差分でH濃度を比較することで装置内バックグランドの影響をある程度無視できる。その場合、処理前後での結晶粒内のH濃度はほとんど変わらないように見える。(f)C-、及び(j)CN-の各イオンは、結晶粒内ではバックグラウンドと同じ大きさであり、TOF-SIMSの検出分解能の範囲において結晶粒内部にはC原子及びN原子は存在しないことがわかった。(i)F-イオンは、結晶粒外周部に強く偏析し、小さい結晶粒においては結晶粒内部でも高濃度で存在していることを観測した。小さい結晶粒はほとんど分解し、SmF3,FeF2、SmOFなどとして存在すると推定される。
FIG. 6 shows (a) total ions, (b) FeO − , (c) FeO 2 − , (d) FeO 2 H − , (250 ° C. for 24 h heat treated magnetic powder measured using TOF-SIMS. e) The ion images of H − , (f) C − , (g) O − , (h) OH − , (i) F − , (j) CN − , and (k) Cl − are shown, respectively. There is a correlation between the ion images of (e) H − and (g) O − , and the O concentration tends to increase corresponding to the H concentration. The comparison between the samples is only a reference level, but the influence of the background in the apparatus can be ignored to some extent by comparing the H concentration by the difference between the resin portion around the magnetic powder and the crystal grains. In that case, it appears that the H concentration in the crystal grains before and after the treatment hardly changes. Each ion of (f) C − and (j) CN − has the same size as the background within the crystal grain, and C atoms and N atoms are present inside the crystal grain within the range of the TOF-SIMS detection resolution. I found that it doesn't exist. (I) It was observed that F - ions were strongly segregated on the outer periphery of the crystal grains, and that small crystals were present at a high concentration even inside the crystal grains. Small crystal grains are almost decomposed and presumed to exist as SmF 3 , FeF 2 , SmOF and the like.
以上の結果、フッ化水素ガスを使用しSm2Fe17磁粉を熱処理することで、Sm2Fe17HαFx(0<α<5、かつ0<x≦3、かつ0<α+x≦5)と表記するのが適切な組成を得た。α,xの上限に関しては、侵入位置の数から自ずと制限される。また、同様にして化学式R3(Fe,T)29HβFy(0<β<6、かつ0<y≦4、かつ0<β+y≦6),化学式R(Fe,T)12HγFz(0<γ<1、かつ0<z<1、かつ0<γ+z≦1)を得る。作製した試料のα,β,γ,x,y,zの値を実験的に得るには、以下の方法で可能である。
As a result of the above, heat treatment of the Sm 2 Fe 17 magnetic powder using hydrogen fluoride gas gave Sm 2 Fe 17 H α F x (0 <α <5, 0 <x ≦ 3, and 0 <α + x ≦ 5 ) Was obtained as a suitable composition. The upper limits of α and x are naturally limited by the number of intrusion positions. Similarly, the chemical formula R 3 (Fe, T) 29 H β F y (0 <β <6 and 0 <y ≦ 4 and 0 <β + y ≦ 6), chemical formula R (Fe, T) 12 H γ F z (0 <γ <1, 0 <z <1, and 0 <γ + z ≦ 1) is obtained. In order to experimentally obtain the α, β, γ, x, y, z values of the prepared sample, the following method is possible.
1つ目は、合成した磁粉をボールミルやジェットミルなどで異相を分離し、磁性吸引,遠心分離などの方法で構造・組成に応じ分けた後、目的相の処理前後での重量、及び化学組成分析の手法による。2つ目は、TOF-SIMSを使用し、目的相での元素定量による。3つめは、広角X線吸収微細構造(Extended X-ray Absorption Fine Structure、EXAFS)測定によるF原子位置,占有率の同定、及びX線・中性子リートベルト解析などによる。また、この他にも磁性材料であるため磁性計測からも同定できる。以上の方法を組み合わせることで、精度を上げて同定することが可能である。
The first is to separate the heterogeneous phase of the synthesized magnetic powder with a ball mill or jet mill, etc., and to separate it according to the structure and composition by methods such as magnetic attraction and centrifugation, and then the weight and chemical composition of the target phase before and after treatment. It depends on the analysis method. Second, using TOF-SIMS and elemental determination in the target phase. The third is the identification of F atom position and occupancy by wide-angle X-ray absorption fine structure (EXAFS) measurement and X-ray / neutron Rietveld analysis. In addition, since it is a magnetic material, it can also be identified from magnetic measurements. By combining the above methods, it is possible to identify with higher accuracy.
図7は、0.5T磁場中における各温度で熱処理したSm2Fe17磁粉の磁化の温度依存性を示す。Sm2Fe17磁粉の磁化は、平均場理論に従う標準的な強磁性体の温度変化である。ただし、200℃以上での磁化の上昇は、測定雰囲気である希薄He中に含まれる微量酸素により相分解し、Feが発生することを意味する。キュリー温度は偏極点から120℃である。キュリー温度は、熱処理温度に応じて上昇し、200℃24h熱処理磁粉において最大260(140℃上昇)になることを観測した。200℃24h熱処理磁粉では、磁化の温度曲線に約190℃と260℃に2つのキュリー温度を観測し、他の熱処理磁粉と比較し磁化の減少の仕方が緩慢であることがわかった。これは、Sm2Fe17への原子侵入の仕方に応じ、主として2つの相に代表されるものの、依然として原子侵入に分布を持つことを意味する。水素化、及びフッ素化の複雑な拡散反応により生じると推定され、その拡散反応機構の詳細は現状よくわかっていない。また、-100℃から-60℃の温度範囲で磁化の飛びを観測し、飛びが発生する温度範囲はキュリー温度の上昇と相関があることがわかった。この温度領域における磁化の飛びは、Feの局在性に関与した磁気異方性の変化であることが知られている。キュリー温度以外の、原子侵入の評価基準としての尺度を有する磁気転移である。すなわち、結晶格子の拡大率とある相関関係を有することになる。350℃24h熱処理磁粉では、Sm2Fe17はFe,SmF3、及びSmOFなどに完全に相分解しており、観測しているのはFeの温度変化である。このような熱磁気特性評価において磁化の温度依存性がブリルアン関数から大きく逸脱して滑らかではない場合は、複数の相が磁化の温度依存性に寄与していることを示唆しており、反応・拡散が一様に生じているか否かの目安を与える。
FIG. 7 shows the temperature dependence of the magnetization of Sm 2 Fe 17 magnetic powder heat-treated at various temperatures in a 0.5T magnetic field. The magnetization of Sm 2 Fe 17 magnetic powder is a temperature change of a standard ferromagnet according to mean field theory. However, an increase in magnetization at 200 ° C. or higher means that Fe is generated by phase decomposition by a trace amount of oxygen contained in dilute He as a measurement atmosphere. The Curie temperature is 120 ° C. from the polarization point. It was observed that the Curie temperature increased according to the heat treatment temperature and reached a maximum of 260 (140 ° C. increase) in the heat treated magnetic powder at 200 ° C. for 24 hours. In the case of heat treated magnetic powder at 200 ° C. for 24 hours, two Curie temperatures were observed at about 190 ° C. and 260 ° C. in the temperature curve of magnetization, and it was found that the method of decreasing the magnetization was slow compared to other heat treated magnetic powder. This means that although it is represented mainly by two phases depending on the way of atom penetration into Sm 2 Fe 17 , it still has a distribution in atom penetration. It is presumed to be caused by a complex diffusion reaction of hydrogenation and fluorination, and details of the diffusion reaction mechanism are not well understood at present. In addition, magnetization jumps were observed in the temperature range from −100 ° C. to −60 ° C., and it was found that the temperature range where the jumps occurred correlated with an increase in the Curie temperature. It is known that the magnetization jump in this temperature region is a change in magnetic anisotropy related to the localization of Fe. It is a magnetic transition having a scale as an evaluation criterion of atom penetration other than the Curie temperature. That is, it has a certain correlation with the expansion rate of the crystal lattice. In the heat-treated magnetic powder at 350 ° C. for 24 hours, Sm 2 Fe 17 is completely phase-decomposed into Fe, SmF 3 , SmOF, etc., and what is observed is the temperature change of Fe. If the temperature dependence of the magnetization is significantly different from the Brillouin function in this thermomagnetic property evaluation, it is suggested that multiple phases contribute to the temperature dependence of the magnetization. Provides a measure of whether the diffusion is uniform.
図8は、Sm2Fe17HxFyにおける(a)結晶格子定数の拡大率Δa/a軸,Δc/c軸、及び単位胞体積の拡大率Δv/v、及び(b)キュリー温度上昇率ΔTC/TCの熱処理温度依存性をそれぞれ示す。また、液体窒素温度(Liq.N),室温(R.T.)における試料全体の(c)保磁力Hc、及び(d)反転磁場分布(Switching field distribution、SFD)の熱処理温度依存性をそれぞれ示す。ただし、拡大率、及び上昇率の基準は、Sm2Fe17磁粉である。SFDは、磁化の磁場依存性を微分解析して得られるピークの半値幅を保磁力で除算することで導出した無次元量である。永久磁石材料の磁化反転磁場の分布の尺度を与える量であるが、今回のような低保磁力の場合、値が小さいほど硬磁性的、値が大きいほど軟磁性的である。(a)結晶格子定数のa軸の拡大率Δa/aは、熱処理温度が200℃のときに最大値をとり、それより高温の熱処理では徐々に減少することを観測した。結晶格子定数のc軸の拡大率Δc/cは、熱処理温度が200℃のときに最小値をとり、それより高温の熱処理では徐々に増加することを観測した。これは、200℃24h熱処理により侵入した原子が、より高温の熱処理では脱離していくと推定される。(b)キュリー温度上昇率も、結晶格子定数のa軸の拡大率Δa/a、及び単位胞体積の拡大率Δv/vと同様の挙動を示し、熱処理温度が200℃のときに最大値をとり、それより高温の熱処理では徐々に減少することを観測した。結晶格子定数とキュリー温度との間に相関関係があることを示唆している。(c)保磁力Hcは、原子侵入が大きくなる200℃以上の熱処理から徐々に減少することを観測した。(d)SFDも、原子侵入が大きくなる200℃以上の熱処理から徐々に増加し、Sm2Fe17が完全に分解する350℃熱処理で急激に大きな値となることを観測した。逆磁区核発生型の保磁力発現機構を有するSm2Fe17構造の結晶組織内(特に結晶外周部)に、熱処理過程で分解し発生した軟磁性であるFeが混入することで、磁化反転が容易に生じ、保磁力の低下やSFDの増加が生じると考えられる。
FIG. 8 shows (a) crystal lattice constant expansion rate Δa / a axis, Δc / c axis, and unit cell volume expansion rate Δv / v, and (b) Curie temperature increase in Sm 2 Fe 17 H x F y . The dependence of the rate ΔT C / T C on the heat treatment temperature is shown. In addition, the heat treatment temperature dependence of (c) coercive force H c and (d) switching field distribution (SFD) of the entire sample at liquid nitrogen temperature (Liq.N), room temperature (RT). Each is shown. However, the standard for the expansion rate and the rate of increase is Sm 2 Fe 17 magnetic powder. SFD is a dimensionless quantity derived by dividing the half width of the peak obtained by differential analysis of the magnetic field dependence of magnetization by the coercive force. This amount gives a measure of the distribution of the magnetization reversal field of the permanent magnet material. In the case of the low coercive force as in this case, the smaller the value, the harder the magnetic material, and the larger the value, the softer the magnetic. (A) It was observed that the a-axis expansion ratio Δa / a of the crystal lattice constant takes a maximum value when the heat treatment temperature is 200 ° C. and gradually decreases with heat treatment at a higher temperature. It was observed that the c-axis expansion ratio Δc / c of the crystal lattice constant takes a minimum value when the heat treatment temperature is 200 ° C. and gradually increases with heat treatment at a higher temperature. This is presumed that atoms invaded by heat treatment at 200 ° C. for 24 hours are desorbed by heat treatment at a higher temperature. (B) The Curie temperature rise rate also exhibits the same behavior as the a-axis expansion rate Δa / a and the unit cell volume expansion rate Δv / v of the crystal lattice constant, and the maximum value when the heat treatment temperature is 200 ° C. However, it was observed that the temperature decreased gradually with heat treatment at higher temperatures. This suggests that there is a correlation between the crystal lattice constant and the Curie temperature. (C) It was observed that the coercive force Hc gradually decreased from a heat treatment at 200 ° C. or higher where atomic penetration increases. (D) It was observed that SFD also gradually increased from the heat treatment at 200 ° C. or higher where atomic penetration increases, and suddenly becomes a large value at 350 ° C. heat treatment in which Sm 2 Fe 17 is completely decomposed. Magnetization reversal occurs when Fe, which is soft magnetism generated by decomposition during heat treatment, is mixed in the crystal structure (especially the outer periphery of the crystal) of the Sm 2 Fe 17 structure having a coercive force generation mechanism of reversed domain nucleation type. It occurs easily, and it is considered that the coercive force decreases and the SFD increases.
図9は、HFによりフッ素化処理したSm2Fe17におけるキュリー温度上昇率ΔTC/TCと単位胞体積の拡大率Δv/vとの相関関係を示す。ただし、単位胞体積は室温における値である。直線近似に際し、近似誤差を小さくする(R因子を大きくする)ため原点を強制的に通過させた。水素化及びフッ素化に際しては、フッ化アンモニウム,酸性フッ化アンモニウム以外にもケイフッ化アンモニウム((NH4F)2SiF6),ほうフッ化アンモニウム(NH4BF4)を使用することで、反応の程度を調整した。単位胞の体積拡大率Δv/vを横軸にキュリー温度上昇率ΔTC/TCを縦軸にとる場合、HFにより合成したSm2Fe17HxFyは傾きが16.0(±0.9)の関係を有することを見出した。キュリー温度は最大で36%上昇し、また単位胞体積は最大で1.9%拡大したSm2Fe17HxCyNzは、同様の相関で整理した場合、侵入原子の種類H,C,Nにはほとんど依存せず、13.3(±0.6)の関係を有することが知られている。線形関係は、主としてSm2Fe17に原子が侵入することによるFe原子の局在性と関係するものである。故に、単位胞体積の拡大率は、H原子及びF原子の侵入量と相関がある。データの点数が少なく、かつ測定点の分布に偏りがあるため近似誤差が大きいが、Sm2Fe17HxFyの方がSm2Fe17HxCyNzよりも傾きが大きい傾向にある。この磁気体積効果における差異は、F原子の強い電気陰性度によるFe原子の局在化の度合いを反映している可能性がある。以上のような相関関係は、原理的に化学式R2(Fe,T)17Fx,化学式R3(Fe,T)29Fy,化学式R(Fe,T)12Fzにおいても観測されることが期待される。
FIG. 9 shows the correlation between the Curie temperature increase rate ΔT C / T C and the unit cell volume expansion rate Δv / v in Sm 2 Fe 17 fluorinated with HF. However, the unit cell volume is a value at room temperature. In the linear approximation, the origin was forcibly passed to reduce the approximation error (increase the R factor). In hydrogenation and fluorination, in addition to ammonium fluoride and acidic ammonium fluoride, ammonium silicofluoride ((NH 4 F) 2 SiF 6 ) and ammonium borofluoride (NH 4 BF 4 ) are used to react. The degree of was adjusted. When the volume expansion rate Δv / v of the unit cell is taken on the horizontal axis and the Curie temperature rise rate ΔT C / T C is taken on the vertical axis, the slope of Sm 2 Fe 17 H x F y synthesized by HF is 16.0 (± 0 .9). Sm 2 Fe 17 H x C y N z , whose Curie temperature rose by a maximum of 36% and whose unit cell volume expanded by a maximum of 1.9% , N are almost independent of each other and are known to have a relationship of 13.3 (± 0.6). The linear relationship is mainly related to the localization of Fe atoms caused by atoms entering Sm 2 Fe 17 . Therefore, the expansion rate of the unit cell volume is correlated with the amount of penetration of H atoms and F atoms. Although the approximation error is large because the number of data points is small and the distribution of measurement points is biased, the slope of Sm 2 Fe 17 H x F y tends to be larger than that of Sm 2 Fe 17 H x C y N z. is there. This difference in magnetovolume effect may reflect the degree of localization of Fe atoms due to the strong electronegativity of F atoms. The above correlation is also observed in principle in the chemical formula R 2 (Fe, T) 17 F x , the chemical formula R 3 (Fe, T) 29 F y , and the chemical formula R (Fe, T) 12 F z . It is expected.
測定した磁粉の平均粒径が10μmであったため、保磁力はわずかであるが、2μmから3μm程度まで粉砕することで顕著な保磁力が発現すると推定される。原理的には、単磁区臨界粒径(0.3μm程度)まで粉砕することが望ましいが、酸化などプロセス上の問題が生じるため、1μm以上である方が望ましい。
Since the measured average particle diameter of the magnetic powder was 10 μm, the coercive force is slight, but it is estimated that a significant coercive force is exhibited by grinding from about 2 μm to about 3 μm. In principle, it is desirable to pulverize to a single domain critical particle size (about 0.3 μm). However, since problems in process such as oxidation occur, it is desirable that the particle size is 1 μm or more.
例えば、図10はフッ化アンモニウム、及び酸性フッ化アンモニウムで300℃1h熱処理したSm3Fe28Tiの粉砕前後での磁化の磁場依存性を示す。粉砕は、ボールミルによるシクロヘキサン溶媒中での湿式粉砕を実施した。溶媒除去後、ステアリン酸で配向し測定した。ただし、ボールミル粉砕により磁粉の2次凝集が生じ磁粉配向度が低下し、また不純物混入などにより、飽和磁化は低目に評価されている。十分な分散・解砕処理、及び不純物除去が必要である。粉砕により保磁力の増加と大きなヒステリシスの発生を確認した。さらに保磁力を増加させるには、逆磁区核反転磁場の向上が必要であり、Zn,Sn、及びその合金、また界面活性剤による酸化抑制などが効果的である。
For example, FIG. 10 shows the magnetic field dependence of magnetization before and after pulverization of Sm 3 Fe 28 Ti heat-treated with ammonium fluoride and ammonium acid fluoride at 300 ° C. for 1 h. The pulverization was performed by wet pulverization in a cyclohexane solvent using a ball mill. After removing the solvent, it was aligned with stearic acid and measured. However, secondary agglomeration of magnetic powder is caused by ball milling and the degree of magnetic powder orientation is lowered, and saturation magnetization is evaluated to be low due to contamination with impurities. Sufficient dispersion and crushing treatment and removal of impurities are necessary. The increase in coercive force and generation of large hysteresis were confirmed by grinding. In order to further increase the coercive force, it is necessary to improve the reverse domain nuclear reversal magnetic field, and it is effective to suppress oxidation by Zn, Sn, and their alloys, and surfactants.
Sm2Fe17をフッ化水素処理することで、面内異方性から1軸異方性へと磁気異方性が変化し、永久磁石材料としての可能性を有する。これは、Smの磁性を担う4f電子軌道が葉巻型を有しているためであり、同様の効果はEr,Tmでも期待される。つまり、希土類元素に働く結晶場を考えると、化学式R2(Fe,T)17HαFx(1≦x),化学式R3(Fe,T)29HβFy(2≦y)において、希土類元素RがSm,Er,Tmの場合、1軸磁気異方性となる。一方、化学式R(Fe,T)12HγFz(0.5≦z)において、希土類元素RがPr,Nd,Tb,Dyの場合、1軸磁気異方性となる。作製した試料のα,β,γ,x,y,zの値を実験的に得るには、上記に既に記載の方法で可能である。1軸磁気異方性は、磁場中配向し固定することで評価可能であり、精度を上げるには粉砕・解砕・分離を行った単相試料に対し評価することが望ましい。
By treating Sm 2 Fe 17 with hydrogen fluoride, the magnetic anisotropy changes from in-plane anisotropy to uniaxial anisotropy, and has the potential as a permanent magnet material. This is because the 4f electron orbit responsible for the magnetism of Sm has a cigar shape, and the same effect is expected for Er and Tm. In other words, when the crystal field acting on the rare earth element is considered, in the chemical formula R 2 (Fe, T) 17 H α F x (1 ≦ x), the chemical formula R 3 (Fe, T) 29 H β F y (2 ≦ y) When the rare earth element R is Sm, Er, or Tm, uniaxial magnetic anisotropy is obtained. On the other hand, when the rare earth element R is Pr, Nd, Tb, Dy in the chemical formula R (Fe, T) 12 H γ F z (0.5 ≦ z), the uniaxial magnetic anisotropy is obtained. In order to experimentally obtain the values of α, β, γ, x, y, and z of the prepared sample, the above-described method can be used. Uniaxial magnetic anisotropy can be evaluated by orientation and fixation in a magnetic field, and it is desirable to evaluate a single-phase sample that has been pulverized, crushed and separated in order to increase accuracy.
例えば、図11は液体窒素温度、及び室温におけるSm3Fe28Tiの磁気異方性エネルギーの、水素化及びフッ素化の熱処理温度依存性を示す。ステアリン酸(融点68℃~71℃)を使用し2T磁場中で配向した試料の垂直方向、及び平行方向に評価し、囲まれる面積を磁気異方性エネルギーとし導出した。ただし、測定装置が±6Tまでしか磁場印加ができないため、飽和漸近則を利用し外挿することで両曲線の交点を計算し、囲まれる面積を導出した。そのため、多少なりとも誤差はある。水素化、及びフッ素化熱処理温度の上昇に伴い、磁気異方性エネルギーが増加する傾向にあることがわかった。このように、水素化、及びフッ素化により磁気異方性が大きくなる。1軸磁気異方性は、そのほかにも強磁性共鳴,メスバウワー,中性子,核磁気共鳴などのミクロ磁性評価手段を用いて解析することでも可能である。
For example, FIG. 11 shows the heat treatment temperature dependence of hydrogenation and fluorination of the liquid nitrogen temperature and the magnetic anisotropy energy of Sm 3 Fe 28 Ti at room temperature. A sample oriented using a stearic acid (melting point 68 ° C. to 71 ° C.) in a 2T magnetic field was evaluated in the vertical direction and the parallel direction, and the enclosed area was derived as the magnetic anisotropy energy. However, since the measuring device can only apply a magnetic field up to ± 6T, the intersection of both curves was calculated by extrapolation using the saturation asymptotic rule, and the enclosed area was derived. Therefore, there are some errors. It was found that the magnetic anisotropy energy tends to increase with increasing hydrogenation and fluorination heat treatment temperatures. Thus, magnetic anisotropy increases by hydrogenation and fluorination. Uniaxial magnetic anisotropy can also be analyzed using micromagnetic evaluation means such as ferromagnetic resonance, Mossbauer, neutrons, and nuclear magnetic resonance.
また、フッ化水素処理に伴い微量酸素の影響でSm2Fe17の一部がやむを得ず分解して発生するα-Feは、磁粉表面に多く存在する傾向にある。結果、磁化反転時の逆磁区核として寄与するため、Zn,Snなどの混合により常磁性相であるZn-Fe合金,Sn-Fe合金を形成することは、保磁力を発現させるには望ましい。また、このような低融点金属、及び低融点合金は磁粉同士を結着し、充填密度を上げて磁束密度を高めることが可能である。
In addition, a large amount of α-Fe, which is inevitably decomposed and generated by a part of Sm 2 Fe 17 due to the influence of a trace amount of oxygen in the treatment with hydrogen fluoride, tends to exist on the surface of the magnetic powder. As a result, since it contributes as a reverse domain nucleus at the time of magnetization reversal, it is desirable to form a Zn—Fe alloy or Sn—Fe alloy that is a paramagnetic phase by mixing Zn, Sn, etc. in order to develop a coercive force. Moreover, such a low melting point metal and a low melting point alloy can bind magnetic powders and increase the packing density to increase the magnetic flux density.
実施例2:F原子及びN原子含有合金
本実施例では、窒素化、及びフッ素化を実施する方法について説明する。Sm2Fe17においては、フッ素原子は300℃よりも高温で結晶格子外に排出され、窒素原子は300℃付近から結晶格子内に取り込まれることを、鋭意研究し明らかにした。そのため、窒素化とフッ素化を同時に実施するのは困難であり、系の安定性から窒素化を先に実施する必要がある。ただし、Fe原子の一部を置換した化学式R2(Fe,T)17,化学式R3(Fe,T)29,化学式R(Fe,T)12(ただし、Rは4f遷移元素またはY,TはFeを除く3d遷移元素、またはAl,Si,Ga,Mo,Nb,W)の系では、フッ素原子、及び窒素原子の吸収・放出温度が異なるため、一概には言えない。以下では、例えばSm2Fe17に対し、窒素化後、フッ素化する方法について詳細に説明する。しかし、同時に実施できるか否かによって、本実施例の範囲は限定されない。窒素原子とフッ素原子が結晶格子内の侵入位置に適当な占有率を有し共存することが本質である。そのため、窒素ガス、及びフッ素ガスの混合や、各ガスの別々の使用、及び窒素化,フッ素化することができるガス,固体の使用も問題ない。 Example 2: F atom and N atom containing alloy In a present Example, the method of implementing nitrogenation and fluorination is demonstrated. In Sm 2 Fe 17 , it has been intensively studied and clarified that fluorine atoms are discharged out of the crystal lattice at a temperature higher than 300 ° C. and nitrogen atoms are taken into the crystal lattice from around 300 ° C. Therefore, it is difficult to carry out nitrogenation and fluorination at the same time, and it is necessary to carry out nitrogenation first in view of the stability of the system. However, chemical formula R 2 (Fe, T) 17 , chemical formula R 3 (Fe, T) 29 , chemical formula R (Fe, T) 12 (where R is a 4f transition element or Y, T In a system of 3d transition elements other than Fe, or Al, Si, Ga, Mo, Nb, W), the absorption and emission temperatures of fluorine atoms and nitrogen atoms are different, so it cannot be generally said. Hereinafter, for example, a method of fluorinating Sm 2 Fe 17 after nitriding will be described in detail. However, the scope of the present embodiment is not limited depending on whether or not it can be performed simultaneously. It is essential that nitrogen atoms and fluorine atoms coexist with an appropriate occupation ratio at the intrusion position in the crystal lattice. Therefore, there is no problem in mixing nitrogen gas and fluorine gas, using each gas separately, and using nitrogen and fluorinated gas or solid.
本実施例では、窒素化、及びフッ素化を実施する方法について説明する。Sm2Fe17においては、フッ素原子は300℃よりも高温で結晶格子外に排出され、窒素原子は300℃付近から結晶格子内に取り込まれることを、鋭意研究し明らかにした。そのため、窒素化とフッ素化を同時に実施するのは困難であり、系の安定性から窒素化を先に実施する必要がある。ただし、Fe原子の一部を置換した化学式R2(Fe,T)17,化学式R3(Fe,T)29,化学式R(Fe,T)12(ただし、Rは4f遷移元素またはY,TはFeを除く3d遷移元素、またはAl,Si,Ga,Mo,Nb,W)の系では、フッ素原子、及び窒素原子の吸収・放出温度が異なるため、一概には言えない。以下では、例えばSm2Fe17に対し、窒素化後、フッ素化する方法について詳細に説明する。しかし、同時に実施できるか否かによって、本実施例の範囲は限定されない。窒素原子とフッ素原子が結晶格子内の侵入位置に適当な占有率を有し共存することが本質である。そのため、窒素ガス、及びフッ素ガスの混合や、各ガスの別々の使用、及び窒素化,フッ素化することができるガス,固体の使用も問題ない。 Example 2: F atom and N atom containing alloy In a present Example, the method of implementing nitrogenation and fluorination is demonstrated. In Sm 2 Fe 17 , it has been intensively studied and clarified that fluorine atoms are discharged out of the crystal lattice at a temperature higher than 300 ° C. and nitrogen atoms are taken into the crystal lattice from around 300 ° C. Therefore, it is difficult to carry out nitrogenation and fluorination at the same time, and it is necessary to carry out nitrogenation first in view of the stability of the system. However, chemical formula R 2 (Fe, T) 17 , chemical formula R 3 (Fe, T) 29 , chemical formula R (Fe, T) 12 (where R is a 4f transition element or Y, T In a system of 3d transition elements other than Fe, or Al, Si, Ga, Mo, Nb, W), the absorption and emission temperatures of fluorine atoms and nitrogen atoms are different, so it cannot be generally said. Hereinafter, for example, a method of fluorinating Sm 2 Fe 17 after nitriding will be described in detail. However, the scope of the present embodiment is not limited depending on whether or not it can be performed simultaneously. It is essential that nitrogen atoms and fluorine atoms coexist with an appropriate occupation ratio at the intrusion position in the crystal lattice. Therefore, there is no problem in mixing nitrogen gas and fluorine gas, using each gas separately, and using nitrogen and fluorinated gas or solid.
R(SmまたはNd)-Fe系主相合金は、実施例1と同様の方法で作製した。当然ながら、合金の作製方法によって限定されない。窒素化及びフッ素化は、三フッ化窒素(NF3、純度99.99%以上)ガスを使用した。反応装置は、十分な肉厚を確保したNi製の反応容器を使用した。この他にも、インコネル,モネルなどNi基合金が使用できる。試料容器はステンレスを使用した。事前に、反応容器内に試料容器を配置し、使用温度よりも高温で三フッ化窒素を導入し十分な時間を掛け不動態化処理を行った。
The R (Sm or Nd) —Fe-based main phase alloy was produced in the same manner as in Example 1. Of course, it is not limited by the manufacturing method of the alloy. Nitrogenation and fluorination used nitrogen trifluoride (NF 3 , purity 99.99% or more) gas. As the reaction apparatus, a Ni reaction vessel having a sufficient wall thickness was used. In addition, Ni-based alloys such as Inconel and Monel can be used. Stainless steel was used for the sample container. In advance, a sample container was placed in the reaction container, and nitrogen trifluoride was introduced at a temperature higher than the working temperature, and a passivation process was performed for a sufficient time.
例えば、本実施例では以下の手順で実施した。試料5gをステンレス容器(5cm×7cm)に薄く広げ、配置した。真空引き(0.4kPa),Ar(純度99.9995%以上)置換の操作を3回実施した。希薄Ar中にて120℃まで昇温後、水分を除去する目的で再び真空引き,Ar置換の操作を実施した。その後、窒素化のための温度T1まで昇温し、三フッ化窒素ガスを導入した。導入した三フッ化窒素ガスは、事前にArと混合調整し、濃度は理想気体換算で10%程度である。また、処理した圧力は90kPaとした。三フッ化窒素を導入し1時間保持し、フッ素化のための温度T2まで炉冷し、4時間保持した。処理温度T1,T2の選定、及び各保持時間の選定は、侵入位置の占有率、及び原子の拡散を支配する。完全に窒素化が進行した場合、フッ素原子の侵入する位置がなくなりフッ素化が生じなくなるため、適宜調整が必要である。保持後、十分な排気処理を実施し、Ar雰囲気中で炉冷し40℃以下で大気解放した。
For example, in this example, the following procedure was used. A sample 5 g was thinly spread and placed in a stainless steel container (5 cm × 7 cm). The operation of evacuation (0.4 kPa) and Ar (purity 99.9995% or more) replacement was performed three times. After raising the temperature to 120 ° C. in dilute Ar, vacuuming and Ar replacement were performed again for the purpose of removing moisture. Thereafter, the temperature was raised to a temperature T 1 for nitrogenation, and nitrogen trifluoride gas was introduced. The introduced nitrogen trifluoride gas is mixed and adjusted in advance with Ar, and the concentration is about 10% in terms of ideal gas. The treated pressure was 90 kPa. Nitrogen trifluoride was introduced and held for 1 hour, furnace cooled to a temperature T 2 for fluorination, and held for 4 hours. The selection of the processing temperatures T 1 and T 2 and the selection of each holding time dominate the penetration rate occupancy and the atomic diffusion. When the nitrogenation has completely progressed, the position where the fluorine atom penetrates disappears and the fluorination does not occur. Therefore, appropriate adjustment is necessary. After holding, sufficient exhaust treatment was performed, and the furnace was cooled in an Ar atmosphere and released to the atmosphere at 40 ° C. or lower.
表1は、各温度で熱処理したSm2Fe17のキュリー温度を示す。このように熱処理温度の違いによりキュリー温度が異なることがわかった。熱処理温度の違いは、窒素化、及びフッ素化の程度に差異を生じさせるため、窒素化、及びフッ素化することでキュリー温度が上昇することを示している。フッ素化することでSm2Fe17N3のキュリー温度470℃を上回ることである。図13は、Sm2Fe17,Sm2Fe17N3、及びSm2Fe17NαFxの粉末X線回折パターンを示す。回折パターンはTh2Zn17構造と同じ対称性を有しており、ピーク角度はキュリー温度が大きいものほど低角側にシフトしていることがわかった。キュリー温度と結晶格子の大きさには相関があることを示しており、磁気体積効果の1つの現れといえる。
Table 1 shows the Curie temperature of Sm 2 Fe 17 heat-treated at each temperature. Thus, it was found that the Curie temperature differs depending on the difference in heat treatment temperature. Since the difference in the heat treatment temperature causes a difference in the degree of nitridation and fluorination, it indicates that the Curie temperature rises by nitridation and fluorination. By fluorination, the Curie temperature of Sm 2 Fe 17 N 3 exceeds 470 ° C. FIG. 13 shows powder X-ray diffraction patterns of Sm 2 Fe 17 , Sm 2 Fe 17 N 3 , and Sm 2 Fe 17 N α F x . It was found that the diffraction pattern had the same symmetry as the Th 2 Zn 17 structure, and the peak angle shifted to the lower angle side as the Curie temperature increased. This indicates that there is a correlation between the Curie temperature and the size of the crystal lattice, which is one manifestation of the magnetic volume effect.
TOF-SIMSによる詳細な組成分析から、結晶粒中心部の母相と推定される領域からN原子、及びF原子を検出した。窒素化、及びフッ素化する際にSm2Fe17相の不均一化により多少のSm,Feの分解・発生を回避することは避け難く、フッ素化後の磁粉外周部にはSmN,SmF3,SmOF,Fe,FeN,FeF2、及びFeF3が存在していた。つまり、熱処理温度に依存するが、希土類鉄を窒素化、及びフッ素化する際には、少なくとも希土類窒化物,希土類フッ化物,希土類酸フッ化物,鉄、及び鉄フッ化物のいずれか1つを含むことになる。O原子は、磁粉外周部に付着した水分や熱処理中の酸化が原因であり、やむを得ず混入している。望ましくは排除すべき原子である。熱処理時間を長くすることで窒素化、及びフッ素化を結晶粒内部まで進行させることが可能である。熱処理時間が短い場合、結晶粒外周部からN原子、及びF原子が侵入・拡散していくため、必然的にN原子、及びF原子が、結晶粒界から母相中心に向けて濃度勾配を有することになる。F原子の方が、N原子よりも拡散速度が遅いために、F原子において濃度の不均一性は大きい傾向にある。
From detailed composition analysis by TOF-SIMS, N atoms and F atoms were detected from the region presumed to be the parent phase at the center of the crystal grains. It is unavoidable to avoid some decomposition and generation of Sm and Fe due to non-uniformity of the Sm 2 Fe 17 phase during nitrogenization and fluorination, and the outer periphery of the magnetic powder after fluorination has SmN, SmF 3 , SmOF, Fe, FeN, FeF 2 and FeF 3 were present. That is, depending on the heat treatment temperature, at least one of rare earth nitride, rare earth fluoride, rare earth oxyfluoride, iron, and iron fluoride is included when nitriding and fluorinating rare earth iron It will be. O atoms are caused by moisture adhering to the outer periphery of the magnetic powder and oxidation during heat treatment, and are unavoidably mixed. Desirably, it is an atom to be excluded. By increasing the heat treatment time, it is possible to advance the nitrogenation and fluorination to the inside of the crystal grains. When the heat treatment time is short, N atoms and F atoms penetrate and diffuse from the outer periphery of the crystal grains, so that N and F atoms inevitably have a concentration gradient from the grain boundary toward the parent phase center. Will have. Since the diffusion rate of F atoms is slower than that of N atoms, the concentration non-uniformity tends to be large in F atoms.
以上の結果から、三フッ化窒素雰囲気中でSm2Fe17を熱処理することで、Sm2Fe17NαFxを合成することができ、キュリー温度の上昇を確認した。キュリー温度の上昇以外にも磁気モーメントの増加,磁気異方性の改善を観測した。また、Sm3Fe28Ti、及びNdFe11Tiに関しても別途実施し、概ね同じ傾向を観測した。
From the above results, Sm 2 Fe 17 N α F x can be synthesized by heat-treating Sm 2 Fe 17 in a nitrogen trifluoride atmosphere, and an increase in the Curie temperature was confirmed. Besides increasing the Curie temperature, we observed an increase in magnetic moment and an improvement in magnetic anisotropy. Separately conducted with regard Sm 3 Fe 28 Ti, and NdFe 11 Ti, it was observed almost the same tendency.
測定した磁粉の平均粒径が10μmであったため、保磁力はわずかであったが、2μmから3μm程度まで粉砕することで顕著な保磁力が発現すると推定される。原理的には、単磁区臨界粒径(0.3μm程度)まで粉砕することが望ましいが、酸化などプロセス上の問題が生じるため、1μm以上である方が望ましい。Sm2Fe17に窒素原子,フッ素原子が侵入することで、面内異方性から1軸異方性へと磁気異方性が変化し、永久磁石材料としての可能性を有する。これは、Smの磁性を担う4f電子軌道が葉巻型を有しているためであり、同様の効果はEr,Tmでも期待される。つまり、希土類元素に働く結晶場を考えると、化学式R2(Fe,T)17NαFx(1≦α+x),化学式R3(Fe,T)29NβFy(2≦β+y)において、希土類元素RがSm,Er,Tmの場合、1軸磁気異方性となる。一方、化学式R(Fe,T)12NγFz(0.5≦γ+z)において、希土類元素RがPr,Nd,Tb,Dyの場合、1軸磁気異方性となる。1軸磁気異方性は、実施例1に記載の方法で評価可能である。作製した試料のα,β,γ,x,y,zの値を実験的に得るには、実施例1に記載の分析方法で可能である。
Since the measured magnetic powder had an average particle size of 10 μm, the coercive force was slight, but it is estimated that a significant coercive force is exhibited by grinding from about 2 μm to about 3 μm. In principle, it is desirable to pulverize to a single domain critical particle size (about 0.3 μm). However, since problems in process such as oxidation occur, it is desirable that the particle size is 1 μm or more. When nitrogen atoms and fluorine atoms enter Sm 2 Fe 17 , the magnetic anisotropy changes from in-plane anisotropy to uniaxial anisotropy, and has the potential as a permanent magnet material. This is because the 4f electron orbit responsible for the magnetism of Sm has a cigar shape, and the same effect is expected for Er and Tm. In other words, when the crystal field acting on the rare earth element is considered, in the chemical formula R 2 (Fe, T) 17 N α F x (1 ≦ α + x), the chemical formula R 3 (Fe, T) 29 N β F y (2 ≦ β + y) When the rare earth element R is Sm, Er, or Tm, uniaxial magnetic anisotropy is obtained. On the other hand, when the rare earth element R is Pr, Nd, Tb, Dy in the chemical formula R (Fe, T) 12 N γ F z (0.5 ≦ γ + z), the uniaxial magnetic anisotropy is obtained. Uniaxial magnetic anisotropy can be evaluated by the method described in Example 1. In order to experimentally obtain the values of α, β, γ, x, y, and z of the prepared sample, the analysis method described in Example 1 can be used.
実施例3:F原子及びC原子含有合金
本実施例では、炭素化、及びフッ素化を実施する方法について説明する。Sm2Fe17においては、フッ素原子は300℃よりも高温で結晶格子外に排出され、炭素原子は300℃付近から結晶格子内に取り込まれることを、鋭意研究し明らかにした。そのため、炭素化とフッ素化を同時に実施するのは困難であり、系の安定性から炭素化を先に実施する必要がある。また、炭素化は窒素化以上に結晶格子の熱安定性が増すために、炭素化を先に実施することは望ましい。ただし、Fe原子の一部を置換した化学式R2(Fe,T)17,化学式R3(Fe,T)29,化学式R(Fe,T)12(ただし、Rは4f遷移元素またはY,TはFeを除く3d遷移元素、またはAl,Si,Ga,Mo,Nb,W)の系では、フッ素原子、及び炭素原子の吸収・放出温度が異なるため、一概には言えない。以下では、例えばSm2Fe17に対し、炭素化後、フッ素化する方法について詳細に説明する。しかし、同時に実施できるか否かによって、本実施例の範囲は限定されない。炭素原子とフッ素原子が結晶格子内の侵入位置に適当な占有率を有し共存することが本質である。そのため、炭化水素系ガス、及びフッ素ガスなど炭素化,フッ素化することができる物質(固体,気体,液体など状態は問わない)なら問題ない。ただし、炭化水素系ガスとフッ素ガスが激しく反応するため、両ガスの混合は安全上実施しない方が望ましく、プロセス・特性上の利点も少ない。フルオロカーボンを最初から使用する方が効率的、かつ効果的である。Sm3Fe28Ti、及びNdFe11Tiに関してもSm2Fe17とほぼ同様の方法で別途実施した。 Example 3: F-atom and C-atom-containing alloy In this example, a method for carbonization and fluorination will be described. In Sm 2 Fe 17 , it has been intensively studied and clarified that fluorine atoms are discharged out of the crystal lattice at a temperature higher than 300 ° C., and carbon atoms are taken into the crystal lattice from around 300 ° C. Therefore, it is difficult to carry out carbonization and fluorination at the same time, and it is necessary to carry out carbonization first in view of the stability of the system. Moreover, since carbonization increases the thermal stability of the crystal lattice more than nitrogenation, it is desirable to carry out carbonization first. However, chemical formula R 2 (Fe, T) 17 , chemical formula R 3 (Fe, T) 29 , chemical formula R (Fe, T) 12 (where R is a 4f transition element or Y, T In 3d transition elements other than Fe, or Al, Si, Ga, Mo, Nb, W) systems, the absorption and emission temperatures of fluorine atoms and carbon atoms are different, so it cannot be generally stated. Hereinafter, for example, a method of fluorinating Sm 2 Fe 17 after carbonization will be described in detail. However, the scope of the present embodiment is not limited depending on whether or not it can be performed simultaneously. It is essential that the carbon atom and the fluorine atom coexist with an appropriate occupation ratio at the intrusion position in the crystal lattice. Therefore, there is no problem if it is a substance that can be carbonized or fluorinated (such as solid, gas, liquid, etc.) such as hydrocarbon gas and fluorine gas. However, since hydrocarbon gas and fluorine gas react violently, it is desirable not to carry out mixing of both gases for safety, and there are few advantages in terms of process and characteristics. It is more efficient and effective to use the fluorocarbon from the beginning. Sm 3 Fe 28 Ti and NdFe 11 Ti were also separately carried out in substantially the same manner as Sm 2 Fe 17 .
本実施例では、炭素化、及びフッ素化を実施する方法について説明する。Sm2Fe17においては、フッ素原子は300℃よりも高温で結晶格子外に排出され、炭素原子は300℃付近から結晶格子内に取り込まれることを、鋭意研究し明らかにした。そのため、炭素化とフッ素化を同時に実施するのは困難であり、系の安定性から炭素化を先に実施する必要がある。また、炭素化は窒素化以上に結晶格子の熱安定性が増すために、炭素化を先に実施することは望ましい。ただし、Fe原子の一部を置換した化学式R2(Fe,T)17,化学式R3(Fe,T)29,化学式R(Fe,T)12(ただし、Rは4f遷移元素またはY,TはFeを除く3d遷移元素、またはAl,Si,Ga,Mo,Nb,W)の系では、フッ素原子、及び炭素原子の吸収・放出温度が異なるため、一概には言えない。以下では、例えばSm2Fe17に対し、炭素化後、フッ素化する方法について詳細に説明する。しかし、同時に実施できるか否かによって、本実施例の範囲は限定されない。炭素原子とフッ素原子が結晶格子内の侵入位置に適当な占有率を有し共存することが本質である。そのため、炭化水素系ガス、及びフッ素ガスなど炭素化,フッ素化することができる物質(固体,気体,液体など状態は問わない)なら問題ない。ただし、炭化水素系ガスとフッ素ガスが激しく反応するため、両ガスの混合は安全上実施しない方が望ましく、プロセス・特性上の利点も少ない。フルオロカーボンを最初から使用する方が効率的、かつ効果的である。Sm3Fe28Ti、及びNdFe11Tiに関してもSm2Fe17とほぼ同様の方法で別途実施した。 Example 3: F-atom and C-atom-containing alloy In this example, a method for carbonization and fluorination will be described. In Sm 2 Fe 17 , it has been intensively studied and clarified that fluorine atoms are discharged out of the crystal lattice at a temperature higher than 300 ° C., and carbon atoms are taken into the crystal lattice from around 300 ° C. Therefore, it is difficult to carry out carbonization and fluorination at the same time, and it is necessary to carry out carbonization first in view of the stability of the system. Moreover, since carbonization increases the thermal stability of the crystal lattice more than nitrogenation, it is desirable to carry out carbonization first. However, chemical formula R 2 (Fe, T) 17 , chemical formula R 3 (Fe, T) 29 , chemical formula R (Fe, T) 12 (where R is a 4f transition element or Y, T In 3d transition elements other than Fe, or Al, Si, Ga, Mo, Nb, W) systems, the absorption and emission temperatures of fluorine atoms and carbon atoms are different, so it cannot be generally stated. Hereinafter, for example, a method of fluorinating Sm 2 Fe 17 after carbonization will be described in detail. However, the scope of the present embodiment is not limited depending on whether or not it can be performed simultaneously. It is essential that the carbon atom and the fluorine atom coexist with an appropriate occupation ratio at the intrusion position in the crystal lattice. Therefore, there is no problem if it is a substance that can be carbonized or fluorinated (such as solid, gas, liquid, etc.) such as hydrocarbon gas and fluorine gas. However, since hydrocarbon gas and fluorine gas react violently, it is desirable not to carry out mixing of both gases for safety, and there are few advantages in terms of process and characteristics. It is more efficient and effective to use the fluorocarbon from the beginning. Sm 3 Fe 28 Ti and NdFe 11 Ti were also separately carried out in substantially the same manner as Sm 2 Fe 17 .
R(SmまたはNd)-Fe系主相合金は、実施例1と同様の方法で作製した。当然ながら、合金の作製方法によって限定されない。本実施例では炭素化するガスとしてブタン(C4H10、純度99.5%以上)、フッ素化するガスとしてフッ素(F2、純度99.5%以上)をそれぞれ使用し、以下の手順で実施した。試料5gをステンレス容器(5cm×7cm)に薄く広げ、配置した。真空引き(0.4kPa)、Ar(純度99.9995%以上)置換の操作を3回実施した。希薄Ar中にて120℃まで昇温後、水分を除去する目的で再び真空引き,Ar置換の操作を実施した。その後、炭素化のための温度T1まで昇温し、ブタンを導入した。導入したブタンは、濃度100%であり、処理圧力を90kPaとし1時間保持した。ブタンガスを十分に排気しAr雰囲気として、フッ素化のための温度T2まで炉冷した。温度T2に到達後、事前にArと混合調整した濃度10%(理想気体換算)のF2ガスを導入した。処理圧力は90kPaとし、4時間保持した。熱処理温度T1,T2の選定、及び各保持時間の選定は、侵入位置の占有率、及び原子の拡散を支配する。完全に窒素化が進行した場合、フッ素原子の侵入する位置がなくなるため、フッ素化が生じなくなる。熱処理条件は、粒径,粒の表面状態など母相合金の素状に併せて適宜調整が必要である。T1は300℃以上が好ましく、T2は300℃以下が好ましい。本実施例では、T1は350℃、T2は250℃を選定した。保持後、十分な排気処理を実施し、Ar雰囲気中で炉冷し40℃以下で大気解放した。
The R (Sm or Nd) —Fe-based main phase alloy was produced in the same manner as in Example 1. Of course, it is not limited by the manufacturing method of the alloy. In this embodiment, butane (C 4 H 10 , purity 99.5% or more) is used as the gas to be carbonized, and fluorine (F 2 , purity 99.5% or more) is used as the gas to be fluorinated. Carried out. A sample 5 g was thinly spread and placed in a stainless steel container (5 cm × 7 cm). The operation of evacuation (0.4 kPa) and Ar (purity 99.9995% or more) replacement was performed three times. After raising the temperature to 120 ° C. in dilute Ar, vacuuming and Ar replacement were performed again for the purpose of removing moisture. Thereafter, the temperature was raised to a temperature T 1 of the for carbonization was introduced butane. The introduced butane had a concentration of 100% and was maintained at a treatment pressure of 90 kPa for 1 hour. Butane gas was exhausted sufficiently to form an Ar atmosphere, and the furnace was cooled to a temperature T 2 for fluorination. After reaching the temperature T 2 , F 2 gas having a concentration of 10% (in terms of ideal gas) mixed with Ar in advance was introduced. The treatment pressure was 90 kPa and held for 4 hours. The selection of the heat treatment temperatures T 1 and T 2 and the selection of the respective holding times dominate the penetration ratio and the atomic diffusion. When complete nitrification proceeds, there is no position where fluorine atoms enter, and therefore fluorination does not occur. The heat treatment conditions need to be appropriately adjusted according to the shape of the parent phase alloy such as the grain size and the surface state of the grains. T 1 is preferably 300 ° C. or higher, and T 2 is preferably 300 ° C. or lower. In this example, T 1 was selected to be 350 ° C., and T 2 was selected to be 250 ° C. After holding, sufficient exhaust treatment was performed, and the furnace was cooled in an Ar atmosphere and released to the atmosphere at 40 ° C. or lower.
TOF-SIMSによる詳細な組成分析から、結晶粒中心部の母相と推定される領域からC原子、及びF原子を検出した。炭素化、及びフッ素化する際にSm2Fe17相の不均一化により多少のSm,Feの分解・発生を回避することは避け難く、フッ素化後の磁粉外周部にはSmF3,SmOF,Fe,FeF2、及びFeF3が存在していた。O原子は、磁粉外周部に付着した水分や熱処理中の酸化が原因であり、やむを得ず混入している。望ましくは排除すべき原子である。熱処理時間を長くすることで炭素化、及びフッ素化を結晶粒内部まで進行させることが可能である。熱処理時間が短い場合、結晶粒外周部からC原子、及びF原子が侵入・拡散していくため、必然的にC原子、及びF原子が、結晶粒界から母相中心に向けて濃度勾配を有することになる。F原子の方が、C原子よりも拡散速度が遅いために、F原子において濃度の不均一性は大きい傾向にある。
From detailed composition analysis by TOF-SIMS, C atoms and F atoms were detected from a region presumed to be the parent phase at the center of the crystal grains. During carbonization and fluorination, it is difficult to avoid some decomposition and generation of Sm and Fe due to non-uniformity of the Sm 2 Fe 17 phase. SmF 3 , SmOF, Fe, FeF 2 and FeF 3 were present. O atoms are caused by moisture adhering to the outer periphery of the magnetic powder and oxidation during heat treatment, and are unavoidably mixed. Desirably, it is an atom to be excluded. By increasing the heat treatment time, carbonization and fluorination can proceed to the inside of the crystal grains. When the heat treatment time is short, C atoms and F atoms enter and diffuse from the outer periphery of the crystal grains, so that C atoms and F atoms inevitably have a concentration gradient from the grain boundary toward the parent phase center. Will have. Since the diffusion rate of F atoms is slower than that of C atoms, the concentration non-uniformity tends to be large in F atoms.
以上の結果から、ブタンとフッ素ガスを使用してSm2Fe17を熱処理することで、Sm2Fe17CαFxを合成することができ、キュリー温度の上昇を確認した。キュリー温度の上昇以外にも磁気モーメントの増加,磁気異方性の改善を観測した。また、Sm3Fe28Ti、及びNdFe11Tiに関しても別途実施し、概ね同じ傾向を観測した。
From the above results, Sm 2 Fe 17 C α F x can be synthesized by heat-treating Sm 2 Fe 17 using butane and fluorine gas, and an increase in the Curie temperature was confirmed. Besides increasing the Curie temperature, we observed an increase in magnetic moment and an improvement in magnetic anisotropy. Separately conducted with regard Sm 3 Fe 28 Ti, and NdFe 11 Ti, it was observed almost the same tendency.
測定した磁粉の平均粒径が10μmであったため、保磁力はわずかであったが、2μmから3μm程度まで粉砕することで顕著な保磁力が発現すると推定される。原理的には、単磁区臨界粒径(0.3μm程度)まで粉砕することが望ましいが、酸化などプロセス上の問題が生じるため、1μm以上である方が望ましい。Sm2Fe17に窒素原子,フッ素原子が侵入することで、面内異方性から1軸異方性へと磁気異方性が変化し、永久磁石材料としての可能性を有する。これは、Smの磁性を担う4f電子軌道が葉巻型を有しているためであり、同様の効果はEr,Tmでも期待される。つまり、希土類元素に働く結晶場を考えると、化学式R2(Fe,T)17CαFx(1≦α+x),化学式R3(Fe,T)29CβFy(2≦β+y)において、希土類元素RがSm,Er,Tmの場合、1軸磁気異方性となる。一方、化学式R(Fe,T)12CγFz(0.5≦γ+z)において、希土類元素RがPr,Nd,Tb,Dyの場合、1軸磁気異方性となる。
Since the measured magnetic powder had an average particle size of 10 μm, the coercive force was slight, but it is estimated that a significant coercive force is exhibited by grinding from about 2 μm to about 3 μm. In principle, it is desirable to pulverize to a single domain critical particle size (about 0.3 μm). However, since problems in process such as oxidation occur, it is desirable that the particle size is 1 μm or more. When nitrogen atoms and fluorine atoms enter Sm 2 Fe 17 , the magnetic anisotropy changes from in-plane anisotropy to uniaxial anisotropy, and has the potential as a permanent magnet material. This is because the 4f electron orbit responsible for the magnetism of Sm has a cigar shape, and the same effect is expected for Er and Tm. In other words, when the crystal field acting on the rare earth element is considered, in the chemical formula R 2 (Fe, T) 17 C α F x (1 ≦ α + x), the chemical formula R 3 (Fe, T) 29 C β F y (2 ≦ β + y) When the rare earth element R is Sm, Er, or Tm, uniaxial magnetic anisotropy is obtained. On the other hand, in the chemical formula R (Fe, T) 12 C γ F z (0.5 ≦ γ + z), when the rare earth element R is Pr, Nd, Tb, Dy, uniaxial magnetic anisotropy is obtained.
1軸磁気異方性は、実施例1に記載の方法で評価可能である。作製した試料のα,β,
γ,x,y,zの値を実験的に得るには、実施例1に記載の分析方法で可能である。 Uniaxial magnetic anisotropy can be evaluated by the method described in Example 1. Α, β,
In order to experimentally obtain the values of γ, x, y, and z, the analysis method described in Example 1 can be used.
γ,x,y,zの値を実験的に得るには、実施例1に記載の分析方法で可能である。 Uniaxial magnetic anisotropy can be evaluated by the method described in Example 1. Α, β,
In order to experimentally obtain the values of γ, x, y, and z, the analysis method described in Example 1 can be used.
実施例4:磁粉作製
(1)母相合金の生成:
本実施例では、母相の4f遷移元素-3d遷移元素の磁粉として、組成を調整した母合金を急冷することで得られるSmFe系の薄帯を粉砕した磁性粉を使用した。SmFe系母合金はSmとFeを混合して真空あるいは不活性ガス中または還元ガス雰囲気中で溶解し組成を均一化した(溶解鋳造法)。得られた母合金は、平均粒径が10μm程度になるようボールミルを用い不活性ガス中で粗粉砕した。 Example 4: Magnetic powder production (1) Formation of parent phase alloy:
In this example, magnetic powder obtained by pulverizing an SmFe-based ribbon obtained by quenching a mother alloy with a composition adjusted was used as the magnetic powder of the 4f transition element-3d transition element of the parent phase. The SmFe-based master alloy was mixed with Sm and Fe and dissolved in a vacuum or in an inert gas or reducing gas atmosphere to make the composition uniform (dissolution casting method). The obtained master alloy was coarsely pulverized in an inert gas using a ball mill so that the average particle diameter was about 10 μm.
(1)母相合金の生成:
本実施例では、母相の4f遷移元素-3d遷移元素の磁粉として、組成を調整した母合金を急冷することで得られるSmFe系の薄帯を粉砕した磁性粉を使用した。SmFe系母合金はSmとFeを混合して真空あるいは不活性ガス中または還元ガス雰囲気中で溶解し組成を均一化した(溶解鋳造法)。得られた母合金は、平均粒径が10μm程度になるようボールミルを用い不活性ガス中で粗粉砕した。 Example 4: Magnetic powder production (1) Formation of parent phase alloy:
In this example, magnetic powder obtained by pulverizing an SmFe-based ribbon obtained by quenching a mother alloy with a composition adjusted was used as the magnetic powder of the 4f transition element-3d transition element of the parent phase. The SmFe-based master alloy was mixed with Sm and Fe and dissolved in a vacuum or in an inert gas or reducing gas atmosphere to make the composition uniform (dissolution casting method). The obtained master alloy was coarsely pulverized in an inert gas using a ball mill so that the average particle diameter was about 10 μm.
(2)水素化処理,窒素化処理、及びフッ素化処理:
本発明では、実施例1及び実施例2に記載した方法でフッ化水素ガス、または三フッ化窒素を使用し、250℃24時間で熱処理を実施した。 (2) Hydrogenation treatment, nitrogenation treatment, and fluorination treatment:
In the present invention, heat treatment was performed at 250 ° C. for 24 hours using hydrogen fluoride gas or nitrogen trifluoride by the method described in Example 1 and Example 2.
本発明では、実施例1及び実施例2に記載した方法でフッ化水素ガス、または三フッ化窒素を使用し、250℃24時間で熱処理を実施した。 (2) Hydrogenation treatment, nitrogenation treatment, and fluorination treatment:
In the present invention, heat treatment was performed at 250 ° C. for 24 hours using hydrogen fluoride gas or nitrogen trifluoride by the method described in Example 1 and Example 2.
実施例5:塩素化
磁粉として、実施例1で作製した磁粉を使用した。つまり、ジェットミル粉砕により作製したSm2Fe17,Sm3Fe28Ti、及びNdFe11Tiの各磁粉を使用した。 Example 5: Chlorination Magnetic powder produced in Example 1 was used as magnetic powder. That is, magnetic powders of Sm 2 Fe 17 , Sm 3 Fe 28 Ti, and NdFe 11 Ti produced by jet mill grinding were used.
磁粉として、実施例1で作製した磁粉を使用した。つまり、ジェットミル粉砕により作製したSm2Fe17,Sm3Fe28Ti、及びNdFe11Tiの各磁粉を使用した。 Example 5: Chlorination Magnetic powder produced in Example 1 was used as magnetic powder. That is, magnetic powders of Sm 2 Fe 17 , Sm 3 Fe 28 Ti, and NdFe 11 Ti produced by jet mill grinding were used.
塩化水素ガス処理は、塩化アンモニウムを使用した管状炉によるガスフロー形式で実施した。発生する余剰ガスを吸収するために、反応装置の下流にはトラップ機構を設けた。グラッシーカーボン(Glass carbon、GC)ボート上に試料を薄く広げ配置した。ただし、試料容器の材質は炭素以外にも塩化水素に耐性があれば使用できる。上流と下流には、フッ化アンモニウム粉を入れたGCボートを配置した。塩化アンモニウムの仕込み量は、反応空間の大きさ,流すガスの流量,熱処理温度,熱処理時間による。今回は、半径28mm,長さ1200mmの石英管を使用し、磁粉20gに対し、塩化アンモニウムを上流,下流にそれぞれ10g、配置した。ロータリーポンプにより真空排気した後、Arを200ml/min.で流し、電気炉を加熱した。250℃,300℃,350℃,400℃、及び450℃において反応時間が24時間となるように熱処理を実施した。熱処理温度の選定では、Sm2Fe17の分解・酸化反応が比較的小さい低温が望ましいが、塩化アンモニウムの分解が生じる300℃よりも高温を選定した。また、熱処理時間の選定では、水素の存在により、塩素原子は短時間でも十分な拡散が期待できる。ただし、磁粉サイズ,結晶粒径,磁粉の表面状態,組織形状などに大きく依存する。塩化アンモニウムと磁粉を混合してGCボート上に配置する方が、水素化、及び塩素化の促進が期待されるが、フッ化水素発生源と磁粉とが直に接することで、強すぎる酸化還元拡散反応が生じ、磁粉の外周部は希土類塩化物,希土類酸塩化物,鉄塩化物,鉄などに分解する。使用する磁粉の粒径などにより適宜選択する必要がある。混合の際は未反応生成物を除去する目的で、熱処理の最後に真空置換を実施しても構わない。試料は未反応物が付着している可能性があるため、ポリエチレン容器に入れ真空梱包状態で保存した。ただし、塩素化した磁粉は室温においては極めて安定であるため、ガラス瓶でも構わない。本方法は、固気反応であるため反応の不均一性が問題となる。そのため、流動床などを導入し、満遍なく反応が進行するようにすることが望ましい。
The hydrogen chloride gas treatment was carried out in a gas flow format using a tubular furnace using ammonium chloride. In order to absorb the generated surplus gas, a trap mechanism was provided downstream of the reactor. The sample was spread out thinly on a glassy carbon (GC) boat. However, the material of the sample container can be used as long as it is resistant to hydrogen chloride in addition to carbon. A GC boat containing ammonium fluoride powder was disposed upstream and downstream. The amount of ammonium chloride charged depends on the size of the reaction space, the gas flow rate, the heat treatment temperature, and the heat treatment time. This time, a quartz tube having a radius of 28 mm and a length of 1200 mm was used, and 10 g of ammonium chloride was arranged upstream and downstream of 20 g of magnetic powder. After evacuating with a rotary pump, Ar was flowed at 200 ml / min. To heat the electric furnace. Heat treatment was performed at 250 ° C., 300 ° C., 350 ° C., 400 ° C., and 450 ° C. so that the reaction time was 24 hours. In selecting the heat treatment temperature, a low temperature at which the decomposition / oxidation reaction of Sm 2 Fe 17 is relatively small is desirable, but a temperature higher than 300 ° C. at which ammonium chloride is decomposed is selected. In addition, in the selection of the heat treatment time, due to the presence of hydrogen, chlorine atoms can be expected to diffuse sufficiently even in a short time. However, it greatly depends on the magnetic powder size, the crystal grain size, the surface state of the magnetic powder, the structure shape, and the like. It is expected that hydrogen chloride and chlorination will be accelerated if ammonium chloride and magnetic powder are mixed and placed on the GC boat, but the redox is too strong because the hydrogen fluoride source and magnetic powder are in direct contact. A diffusion reaction occurs, and the outer periphery of the magnetic powder is decomposed into rare earth chloride, rare earth acid chloride, iron chloride, iron and the like. It is necessary to select appropriately depending on the particle size of the magnetic powder to be used. At the time of mixing, vacuum substitution may be performed at the end of the heat treatment for the purpose of removing unreacted products. The sample was stored in a vacuum container in a polyethylene container because unreacted material may be attached. However, since the chlorinated magnetic powder is extremely stable at room temperature, it may be a glass bottle. Since this method is a solid-gas reaction, non-uniformity of the reaction becomes a problem. Therefore, it is desirable to introduce a fluidized bed or the like so that the reaction proceeds evenly.
磁気特性評価を実施し、キュリー温度の上昇,磁化の増加、及び磁気異方性の改善を観測した。
磁 気 Magnetic properties were evaluated, and an increase in Curie temperature, an increase in magnetization, and an improvement in magnetic anisotropy were observed.
実施例6:ナノコート処理
本実施例では、フッ素化する際の母相の酸化・分解を抑制するために、薄いフッ化物の膜を周囲に構築した磁粉に対し、フッ素化処理を検討した。 Example 6: Nanocoat treatment In this example, in order to suppress oxidation / decomposition of the mother phase during fluorination, a fluorination treatment was examined on the magnetic powder constructed around a thin fluoride film.
本実施例では、フッ素化する際の母相の酸化・分解を抑制するために、薄いフッ化物の膜を周囲に構築した磁粉に対し、フッ素化処理を検討した。 Example 6: Nanocoat treatment In this example, in order to suppress oxidation / decomposition of the mother phase during fluorination, a fluorination treatment was examined on the magnetic powder constructed around a thin fluoride film.
希土類フッ化物又はアルカリ土類金属フッ化物コート膜の形成処理液は以下のようにして作製した。本実施例ではPrF3を使用した。酢酸Pr、または硝酸Pr(4g)を100mlの水に溶解後、1%に希釈したフッ化水素酸をPrF3が生成するのに必要な当量の90%相当量を攪拌しながら徐々に加え、ゲル状のPrF3を生成させた。遠心分離により上澄み液を除去した後、残存ゲルと同量のメタノールを加え、攪拌・遠心分離する操作を3~10回繰り返すことで陰イオンを取り除き、ほぼ透明なコロイド状のPrF3のメタノール溶液(濃度:PrF3/メタノール=1g/5ml)を作製した。
A processing solution for forming a rare earth fluoride or alkaline earth metal fluoride coating film was prepared as follows. In this example, PrF 3 was used. After dissolving Pr acetate or Pr nitrate (4 g) in 100 ml of water, 90% of the equivalent amount required for PrF 3 to form hydrofluoric acid diluted to 1% is gradually added with stirring. Gel-like PrF 3 was produced. After removing the supernatant by centrifugation, add the same amount of methanol as the remaining gel, and repeat the agitation / centrifugation operation 3 to 10 times to remove the anion, and the almost transparent colloidal PrF 3 methanol solution (Concentration: PrF 3 / methanol = 1 g / 5 ml) was prepared.
希土類フッ化物又はアルカリ土類金属フッ化物コート膜を磁粉に形成するプロセスは以下の方法で実施した。磁粉は、実施例1と同様の方法で作製した。本実施例では、Sm2Fe17、及びNd2Fe17相の磁粉を使用した。磁粉の平均粒径が10μm以下となるまで、ジェットミルを使用し不活性雰囲気中で粉砕した。平均粒径が10μmの磁粉100gに対して10mlのPrF3コート膜形成処理液を添加し、磁粉全体が濡れるのが確認できるまで混合した。PrF3コート膜形成処理した磁粉を2~5torrの減圧下で溶媒のメタノール除去を行った。溶媒の除去を行った磁粉を石英製ボートに移し、1×10-3Paの減圧下で200℃、30分と350℃、30分の熱処理を行った。結果、磁粉重量に対しPrF3を2wt%処理したことになる。
The process of forming the rare earth fluoride or alkaline earth metal fluoride coating film on the magnetic powder was performed by the following method. The magnetic powder was produced by the same method as in Example 1. In this example, Sm 2 Fe 17 and Nd 2 Fe 17 phase magnetic powders were used. It grind | pulverized in the inert atmosphere using the jet mill until the average particle diameter of magnetic powder became 10 micrometers or less. 10 ml of PrF 3 coat film forming solution was added to 100 g of magnetic powder having an average particle diameter of 10 μm, and mixed until it was confirmed that the entire magnetic powder was wet. The magnetic powder subjected to the PrF 3 coating film formation treatment was subjected to methanol removal of the solvent under a reduced pressure of 2 to 5 torr. The magnetic powder from which the solvent had been removed was transferred to a quartz boat and heat-treated at 200 ° C. for 30 minutes and 350 ° C. for 30 minutes under a reduced pressure of 1 × 10 −3 Pa. As a result, 2 wt% of PrF 3 was treated with respect to the magnetic powder weight.
以上の方法で周囲にPrF3の膜を形成した磁粉を、実施例1~3と同じ方法で水素化,窒素化または炭素化、及びフッ素化を実施した。磁粉周りにPrF3で被膜を形成することで、反応が一様に生じることがわかった。また、イオン半径の小さい水素が優先的に磁粉内部に取り込まれる兆候を観測した。PrF3膜の効果の詳細は現状不明であるが、反応の一様性,原子選択拡散,分解抑制などの目的とする場合には有効に寄与すると推定される。
The magnetic powder having a PrF 3 film formed thereon by the above method was hydrogenated, nitrogenated or carbonized, and fluorinated by the same method as in Examples 1 to 3. It was found that the reaction occurs uniformly by forming a film of PrF 3 around the magnetic powder. We also observed signs that hydrogen with a small ion radius was preferentially taken into the magnetic powder. Details of the effect of the PrF 3 film are unknown at present, but it is presumed that it contributes effectively for purposes such as reaction uniformity, atomic selective diffusion, and decomposition suppression.
実施例7:粒径変化
実施例1~3では、固気反応に伴う磁粉外周部から生じる原子拡散により化学反応が進行していくため、結晶粒径が化学反応の一様性、つまりは元素濃度分布の一様性に大きく影響を与える。一般に、温度と時間により拡散は支配されるため、当然ながら量産において粒径制御は必要である。しかし、研究段階においてもF原子はFe基合金中における拡散速度が著しく遅いため、粒径制御は無視できない要素である。そのため、本実施例では磁気物性の粒径依存性を検討した。磁粉は実施例1と同様の方法で作製し、ジェットミルとボールミルを使用し粒径を調整した。分級は行わず、レーザー回折式粒度分布測定装置を使用して平均粒径を評価した。分散が非常に大きいが、おおよその平均粒径が100μm,50μm,25μm,10μm,5μm,3μmの磁粉を準備した。これらをF2ガスによりフッ素化した結果、粒径が小さいほど均一な組成を得た。ただし、粒径が小さいほど酸化の影響が大きく出ており、酸化抑制の程度が組成の均一性に大きく影響を及ぼす。組成評価は、化学分析や実施例1に記載の各種方法で実施できるが、本実施例では、組成の均一性が磁性に表れるため、磁化の温度依存性を主に評価した。本実施例では代表的なSm2Fe17磁粉を準備したが、化学式R2(Fe,T)17,化学式R3(Fe,T)29,化学式R(Fe,T)12(ただし、Rは4f遷移元素またはYであり、TはFeを除く3d遷移元素、またはAl,Si,Ga,Mo,NbもしくはWである)においても化学反応や元素濃度分布の粒径依存性は存在する。 Example 7: Change in particle size In Examples 1 to 3, since the chemical reaction proceeds by atomic diffusion generated from the outer periphery of the magnetic powder accompanying the solid-gas reaction, the crystal particle size is uniform in chemical reaction, that is, the element It greatly affects the uniformity of concentration distribution. In general, since diffusion is controlled by temperature and time, naturally, particle size control is necessary in mass production. However, even in the research stage, since the diffusion rate of F atoms in the Fe-based alloy is extremely slow, particle size control is a factor that cannot be ignored. Therefore, in this example, the particle size dependence of magnetic properties was examined. The magnetic powder was produced by the same method as in Example 1, and the particle size was adjusted using a jet mill and a ball mill. Classification was not performed, and the average particle size was evaluated using a laser diffraction particle size distribution analyzer. Although the dispersion was very large, magnetic powders having approximate average particle diameters of 100 μm, 50 μm, 25 μm, 10 μm, 5 μm, and 3 μm were prepared. As a result of fluorination of these with F 2 gas, a uniform composition was obtained as the particle size decreased. However, the smaller the particle size, the greater the effect of oxidation, and the degree of oxidation inhibition greatly affects the uniformity of the composition. The composition evaluation can be performed by chemical analysis or various methods described in Example 1. In this example, since the uniformity of the composition appears in magnetism, the temperature dependence of magnetization was mainly evaluated. In this example, typical Sm 2 Fe 17 magnetic powder was prepared. Chemical formula R 2 (Fe, T) 17 , chemical formula R 3 (Fe, T) 29 , chemical formula R (Fe, T) 12 (where R is 4f transition element or Y, and T is a 3d transition element other than Fe, or Al, Si, Ga, Mo, Nb, or W), there is a particle size dependence of chemical reaction and element concentration distribution.
実施例1~3では、固気反応に伴う磁粉外周部から生じる原子拡散により化学反応が進行していくため、結晶粒径が化学反応の一様性、つまりは元素濃度分布の一様性に大きく影響を与える。一般に、温度と時間により拡散は支配されるため、当然ながら量産において粒径制御は必要である。しかし、研究段階においてもF原子はFe基合金中における拡散速度が著しく遅いため、粒径制御は無視できない要素である。そのため、本実施例では磁気物性の粒径依存性を検討した。磁粉は実施例1と同様の方法で作製し、ジェットミルとボールミルを使用し粒径を調整した。分級は行わず、レーザー回折式粒度分布測定装置を使用して平均粒径を評価した。分散が非常に大きいが、おおよその平均粒径が100μm,50μm,25μm,10μm,5μm,3μmの磁粉を準備した。これらをF2ガスによりフッ素化した結果、粒径が小さいほど均一な組成を得た。ただし、粒径が小さいほど酸化の影響が大きく出ており、酸化抑制の程度が組成の均一性に大きく影響を及ぼす。組成評価は、化学分析や実施例1に記載の各種方法で実施できるが、本実施例では、組成の均一性が磁性に表れるため、磁化の温度依存性を主に評価した。本実施例では代表的なSm2Fe17磁粉を準備したが、化学式R2(Fe,T)17,化学式R3(Fe,T)29,化学式R(Fe,T)12(ただし、Rは4f遷移元素またはYであり、TはFeを除く3d遷移元素、またはAl,Si,Ga,Mo,NbもしくはWである)においても化学反応や元素濃度分布の粒径依存性は存在する。 Example 7: Change in particle size In Examples 1 to 3, since the chemical reaction proceeds by atomic diffusion generated from the outer periphery of the magnetic powder accompanying the solid-gas reaction, the crystal particle size is uniform in chemical reaction, that is, the element It greatly affects the uniformity of concentration distribution. In general, since diffusion is controlled by temperature and time, naturally, particle size control is necessary in mass production. However, even in the research stage, since the diffusion rate of F atoms in the Fe-based alloy is extremely slow, particle size control is a factor that cannot be ignored. Therefore, in this example, the particle size dependence of magnetic properties was examined. The magnetic powder was produced by the same method as in Example 1, and the particle size was adjusted using a jet mill and a ball mill. Classification was not performed, and the average particle size was evaluated using a laser diffraction particle size distribution analyzer. Although the dispersion was very large, magnetic powders having approximate average particle diameters of 100 μm, 50 μm, 25 μm, 10 μm, 5 μm, and 3 μm were prepared. As a result of fluorination of these with F 2 gas, a uniform composition was obtained as the particle size decreased. However, the smaller the particle size, the greater the effect of oxidation, and the degree of oxidation inhibition greatly affects the uniformity of the composition. The composition evaluation can be performed by chemical analysis or various methods described in Example 1. In this example, since the uniformity of the composition appears in magnetism, the temperature dependence of magnetization was mainly evaluated. In this example, typical Sm 2 Fe 17 magnetic powder was prepared. Chemical formula R 2 (Fe, T) 17 , chemical formula R 3 (Fe, T) 29 , chemical formula R (Fe, T) 12 (where R is 4f transition element or Y, and T is a 3d transition element other than Fe, or Al, Si, Ga, Mo, Nb, or W), there is a particle size dependence of chemical reaction and element concentration distribution.
以下、結晶格子内にF原子が侵入した場合のFe原子の変位について図を用いて説明する。
Hereinafter, the displacement of Fe atoms when F atoms enter the crystal lattice will be described with reference to the drawings.
図13Aは、Th2Zn17型構造である六方晶の結晶格子内に侵入したF原子の位置を模式的に示す斜視図である。
FIG. 13A is a perspective view schematically showing a position of an F atom that has entered a hexagonal crystal lattice having a Th 2 Zn 17 type structure.
本図において、Rは、4f遷移元素またはYである(図13B及び図13Cにおいても同じ。)。
In this figure, R is a 4f transition element or Y (the same applies to FIGS. 13B and 13C).
図13Bは、Nd3(Fe,Ti)29型構造である単斜晶の結晶格子内に侵入したF原子の位置を模式的に示す斜視図である。
FIG. 13B is a perspective view schematically showing the position of an F atom that has entered the monoclinic crystal lattice having an Nd 3 (Fe, Ti) 29 type structure.
本図において、Tは、Feを除く3d遷移元素、またはAl,Si,Ga,Mo,NbもしくはWである(図13Cにおいても同じ。)。
In this figure, T is a 3d transition element other than Fe, or Al, Si, Ga, Mo, Nb, or W (the same applies to FIG. 13C).
図13Cは、ThMn12型構造である正方晶の結晶格子内に侵入したF原子の位置を模式的に示す斜視図である。
FIG. 13C is a perspective view schematically showing the position of an F atom that has entered a tetragonal crystal lattice having a ThMn 12 type structure.
図14Aは、六方晶の結晶格子内にF原子が侵入した場合のFe原子の変位を模式的に示す(001)面図である。
FIG. 14A is a (001) plane view schematically showing the displacement of Fe atoms when F atoms enter the hexagonal crystal lattice.
図14Bは、六方晶の結晶格子内にF原子が侵入した場合のFe原子の変位を模式的に示す(003)面図である。
FIG. 14B is a (003) plane view schematically showing displacement of Fe atoms when F atoms enter the hexagonal crystal lattice.
図14A及び図14Bにおいて、結晶格子を構成する元素は、Sm、Fe及びFである。図中、Feは、六角形の頂点に位置している。
14A and 14B, the elements constituting the crystal lattice are Sm, Fe, and F. In the figure, Fe is located at the apex of the hexagon.
結晶格子内にF原子が侵入すると、六角形を構成するFe原子が六角形の中心に向かって変位する。これにより、Feのフェルミ準位付近での状態密度が低下し、Feの局在性が増大する。また、磁化が増加し、キュリー温度が上昇する。さらに、F原子の強い電気陰性度によって磁気異方性が改善する。
When F atoms enter the crystal lattice, Fe atoms constituting the hexagon are displaced toward the center of the hexagon. Thereby, the density of states in the vicinity of the Fermi level of Fe decreases, and the localization of Fe increases. Also, the magnetization increases and the Curie temperature rises. Furthermore, magnetic anisotropy is improved by the strong electronegativity of F atoms.
Claims (16)
- 化学式R-Fe(式中、Rは4f遷移元素またはYである。)で表される2元系の合金、あるいは化学式R-Fe-T(式中、Rは前記の通りであり、TはFeを除く3d遷移元素、またはAl,Si,Ga,Mo,NbもしくはWである。但し、TがWである場合、RはW以外の4f遷移元素またはYである。)の3元系の合金を含み、前記合金は、結晶格子内の侵入位置にF原子と、N原子、H原子またはC原子とを含むことを特徴とする磁石材料。 A binary alloy represented by the chemical formula R—Fe (wherein R is a 4f transition element or Y), or a chemical formula R—Fe—T (wherein R is as defined above, T is 3d transition elements other than Fe, or Al, Si, Ga, Mo, Nb or W. However, when T is W, R is a 4f transition element other than W or Y. A magnet material comprising an alloy, wherein the alloy contains an F atom and an N atom, an H atom or a C atom at an intrusion position in a crystal lattice.
- 前記合金は、
化学式R2Fe17NαFx(0<α<3、かつ0<x<3、かつ0<α+x≦3)、
化学式R3(Fe,T)29NβFy(0<β<4、かつ0<y<4、かつ0<β+y≦4)または
化学式R(Fe,T)12NγFz(0<γ<1、かつ0<z<1、かつ0<γ+z≦1)
で表されることを特徴とする請求項1に記載の磁石材料。 The alloy is
Chemical formula R 2 Fe 17 N α F x (0 <α <3 and 0 <x <3 and 0 <α + x ≦ 3),
Chemical formula R 3 (Fe, T) 29 N β F y (0 <β <4 and 0 <y <4 and 0 <β + y ≦ 4) or chemical formula R (Fe, T) 12 N γ F z (0 < γ <1, and 0 <z <1, and 0 <γ + z ≦ 1)
The magnet material according to claim 1, wherein - 前記合金は、化学式R2Fe17NαFx(RはSm,ErまたはTmであり、0<α<3、かつ0<x<3、かつ1≦α+x≦3である。)で表されることを特徴とする請求項2に記載の磁石材料。 The alloy is represented by the chemical formula R 2 Fe 17 N α F x where R is Sm, Er or Tm, 0 <α <3, 0 <x <3, and 1 ≦ α + x ≦ 3. The magnet material according to claim 2, wherein:
- 前記合金は、化学式R3(Fe,T)29NβFy(RはSm,ErまたはTmであり、0<β<4、かつ0<y<4、かつ2≦β+y≦4である。)で表されることを特徴とする請求項2に記載の磁石材料。 The alloy has the chemical formula R 3 (Fe, T) 29 N β F y (R is Sm, Er or Tm, 0 <β <4, 0 <y <4, and 2 ≦ β + y ≦ 4. The magnet material according to claim 2, which is represented by:
- 前記合金は、化学式R(Fe,T)12NγFz(RがPr,Nd,TbまたはDyであり、0<γ<1、かつ0<z<1、かつ0.5≦γ+z≦1である。)で表されることを特徴とする請求項2に記載の磁石材料。 The alloy has the chemical formula R (Fe, T) 12 N γ F z (R is Pr, Nd, Tb or Dy, 0 <γ <1, 0 <z <1, and 0.5 ≦ γ + z ≦ 1. The magnet material according to claim 2, wherein the magnet material is expressed by:
- 前記合金は、
化学式R2Fe17HαFx(0<α<5、かつ0<x≦3、かつ0<α+x≦5)、
化学式R3(Fe,T)29HβFy(0<β<6、かつ0<y≦4、かつ0<β+y≦6)または
化学式R(Fe,T)12HγFz(0<γ<1、かつ0<z<1、かつ0<γ+z≦1)
で表されることを特徴とする請求項1に記載の磁石材料。 The alloy is
Chemical formula R 2 Fe 17 H α F x (0 <α <5 and 0 <x ≦ 3 and 0 <α + x ≦ 5),
Chemical formula R 3 (Fe, T) 29 H β F y (0 <β <6 and 0 <y ≦ 4 and 0 <β + y ≦ 6) or chemical formula R (Fe, T) 12 H γ F z (0 < γ <1, and 0 <z <1, and 0 <γ + z ≦ 1)
The magnet material according to claim 1, wherein - 前記合金は、化学式R2Fe17HαFx(RはSm,ErまたはTmであり、0<α≦4、かつ1≦x≦3、かつ1<α+x≦5である。)で表されることを特徴とする請求項6に記載の磁石材料。 The alloy is represented by the chemical formula R 2 Fe 17 H α F x, where R is Sm, Er or Tm, 0 <α ≦ 4, 1 ≦ x ≦ 3, and 1 <α + x ≦ 5. The magnet material according to claim 6.
- 前記合金は、化学式R3(Fe,T)29HβFy(RはSm,ErまたはTmであり、0<β≦4、かつ2≦y≦4、かつ2<β+y≦6である。)で表されることを特徴とする請求項6に記載の磁石材料。 The alloy has the chemical formula R 3 (Fe, T) 29 H β F y (R is Sm, Er or Tm, 0 <β ≦ 4, 2 ≦ y ≦ 4, and 2 <β + y ≦ 6). The magnet material according to claim 6, which is represented by:
- 前記合金は、化学式R(Fe,T)12HγFz(RはPr,Nd,TbまたはDyであり、0<γ≦0.5、かつ0.5≦z<1、かつ0.5<γ+z≦1である。)で表されることを特徴とする請求項6に記載の磁石材料。 The alloy has the chemical formula R (Fe, T) 12 H γ F z (R is Pr, Nd, Tb or Dy, 0 <γ ≦ 0.5, 0.5 ≦ z <1, and 0.5 The magnetic material according to claim 6, wherein <γ + z ≦ 1.
- 前記合金は、
化学式R2Fe17CαFx(0<α<3、かつ0<x<3、かつ0<α+x≦3)、
化学式R3(Fe,T)29CβFy(0<β<4、かつ0<y<4、かつ0<β+y≦4)または
化学式R(Fe,T)12CγFz(0<γ<1、かつ0<z<1、かつ0<γ+z≦1)
で表されることを特徴とする請求項1に記載の磁石材料。 The alloy is
Chemical formula R 2 Fe 17 C α F x (0 <α <3 and 0 <x <3 and 0 <α + x ≦ 3),
Chemical formula R 3 (Fe, T) 29 C β F y (0 <β <4 and 0 <y <4 and 0 <β + y ≦ 4) or chemical formula R (Fe, T) 12 C γ F z (0 < γ <1, and 0 <z <1, and 0 <γ + z ≦ 1)
The magnet material according to claim 1, wherein - 前記合金は、化学式R2Fe17CαFx(RはSm,ErまたはTmであり、0<α<3、かつ0<x<3、かつ1≦α+x≦3である。)で表されることを特徴とする請求項10に記載の磁石材料。 The alloy is represented by the chemical formula R 2 Fe 17 C α F x, where R is Sm, Er or Tm, 0 <α <3, 0 <x <3, and 1 ≦ α + x ≦ 3. The magnet material according to claim 10.
- 前記合金は、化学式R3(Fe,T)29CβFy(RはSm,ErまたはTmであり、0<β<4、かつ0<y<4、かつ2≦β+y≦4である。)で表されることを特徴とする請求項10に記載の磁石材料。 The alloy has the chemical formula R 3 (Fe, T) 29 C β F y (R is Sm, Er or Tm, 0 <β <4, 0 <y <4, and 2 ≦ β + y ≦ 4. The magnet material according to claim 10, which is represented by:
- 前記合金は、化学式R(Fe,T)12CγFz(RはPr,Nd,TbまたはDyであり、0<γ<1、かつ0<z<1、かつ0.5≦γ+z≦1である。)で表されることを特徴とする請求項10に記載の磁石材料。 The alloy has the chemical formula R (Fe, T) 12 C γ F z (R is Pr, Nd, Tb or Dy, 0 <γ <1, 0 <z <1, and 0.5 ≦ γ + z ≦ 1. The magnetic material according to claim 10, which is expressed by:
- 前記合金は、希土類窒化物,希土類フッ化物,希土類酸フッ化物,鉄及び鉄フッ化物からなる群から選択される少なくとも1種を更に含むことを特徴とする請求項1~13のいずれかに記載の磁石材料。 The alloy according to any one of claims 1 to 13, wherein the alloy further includes at least one selected from the group consisting of rare earth nitrides, rare earth fluorides, rare earth oxyfluorides, iron and iron fluorides. Magnet material.
- 請求項1~14のいずれかに記載の磁石材料とバインダーとを含むことを特徴とする磁石成形品。 A magnet molded product comprising the magnet material according to any one of claims 1 to 14 and a binder.
- 請求項1~14のいずれかに記載の磁石材料を含む回転子を有することを特徴とする回転機。 A rotating machine comprising a rotor including the magnet material according to any one of claims 1 to 14.
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