WO2020095518A1 - Method for producing negative thermal expansion material - Google Patents

Method for producing negative thermal expansion material Download PDF

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WO2020095518A1
WO2020095518A1 PCT/JP2019/033963 JP2019033963W WO2020095518A1 WO 2020095518 A1 WO2020095518 A1 WO 2020095518A1 JP 2019033963 W JP2019033963 W JP 2019033963W WO 2020095518 A1 WO2020095518 A1 WO 2020095518A1
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thermal expansion
negative thermal
expansion material
organic acid
producing
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PCT/JP2019/033963
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French (fr)
Japanese (ja)
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康司 竹中
佳比古 岡本
昌哉 三田村
尚幸 片山
泰範 横山
みく 佐藤
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国立大学法人名古屋大学
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Priority to JP2020556623A priority Critical patent/JP7441522B2/en
Publication of WO2020095518A1 publication Critical patent/WO2020095518A1/en

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G31/00—Compounds of vanadium
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/495—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on vanadium, niobium, tantalum, molybdenum or tungsten oxides or solid solutions thereof with other oxides, e.g. vanadates, niobates, tantalates, molybdates or tungstates
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B

Definitions

  • the present invention relates to a negative thermal expansion material.
  • Non-Patent Document 1 a negative thermal expansion material whose lattice volume decreases (has a negative coefficient of thermal expansion) with an increase in temperature.
  • a composite material that suppresses thermal expansion by mixing ⁇ -Cu 2 V 2 O 7 having a negative coefficient of thermal expansion with Al having a positive coefficient of thermal expansion is known (Non-Patent Document 1). .. Further, ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 in which a part of Cu in Cu 2 V 2 O 7 is replaced with Zn is known to have a larger negative thermal expansion coefficient (Non-Patent Document 1). 2).
  • ⁇ -Cu 2 V 2 O 7 exhibits a negative thermal expansion of ⁇ 5 to ⁇ 6 ppm / ° C. as a linear expansion coefficient in a temperature range of room temperature to 200 ° C.
  • ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 exhibits negative thermal expansion of -14.4 ppm / ° C in linear expansion coefficient in a wide temperature range of -173 ° C to 427 ° C. Has been.
  • the negative thermal expansion material powder having a small particle size can be used as a resin material for injection molding, can be compounded with other materials, and can be applied to minute members, and thus has extremely high utility value.
  • the above-mentioned negative thermal expansion of ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 is considered to be derived from the material structure effect peculiar to ceramic particles, and if it is simply pulverized, negative thermal expansion will occur. The organization that you do will break. Therefore, it is not easy to produce fine particles exhibiting negative thermal expansion, and the method has not been examined in the above-mentioned prior documents.
  • the present disclosure has been made in view of such circumstances, and one of the aims thereof is to provide a new method for producing a negative thermal expansion material.
  • a method for producing a negative thermal expansion material provides a method represented by the general formula (1): Cu 2 ⁇ x R x V 2 O 7 (R is Zn, Ga, Fe, Sn, Mn). At least one element selected from) and a step of preparing an aqueous solution containing a raw material of a compound represented by the formula and an organic acid.
  • FIG. 3 is a diagram showing thermal expansion characteristics of an oxide sintered body represented by ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 manufactured by various methods / conditions.
  • FIG. 8A is a diagram showing the relationship between the particle size and the volume frequency of the negative thermal expansion material according to Example 3, and FIG. 8B is the particle size and volume of the negative thermal expansion material according to Example 4.
  • FIG. 8C is a diagram showing the relationship with the frequency, and FIG.
  • FIG. 8C is a diagram showing the relationship between the particle size and the volume frequency of the negative thermal expansion material according to Example 1.
  • FIG. 9 is a diagram showing X-ray diffraction patterns of the negative thermal expansion materials according to Example 3, Example 4, and Example 1.
  • 10A is a diagram schematically showing crystal grains in an SEM photograph
  • FIG. 10B is a diagram showing internal structures of crystal grains
  • FIG. 10C is a mechanism of negative thermal expansion. It is a figure for explaining.
  • the present inventors have focused on the Cu 2 V 2 O 7 system as a candidate for a substance exhibiting negative thermal expansion.
  • ⁇ -Cu 2 V 2 O 7 having a rectangular crystal structure is of interest as a multiferroic substance in which ferroelectricity and weak paramagnetism coexist, but it has a relatively wide temperature range including room temperature and higher temperatures. In the region, anisotropic thermal deformation of the crystal lattice, which is probably due to dielectric instability, is observed. As a result, negative thermal expansion occurs in which the unit cell volume contracts with increasing temperature in a wide temperature range.
  • Cu 2 V 2 O 7 can assume a monoclinic ⁇ phase and a triclinic ⁇ phase in addition to the orthorhombic ⁇ phase. Therefore, the inventors of the present invention should develop negative thermal expansion characteristics that cannot be realized by the conventional ⁇ -Cu 2 V 2 O 7 system, when a part of the Cu site or V site is replaced with another element. The inventors have devised a negative thermal expansion material and a method for producing the same, which are exemplified below.
  • one embodiment of the present disclosure is to provide at least one element selected from the general formula (1): Cu 2 ⁇ x R x V 2 O 7 (R is Zn, Ga, Fe, Sn, Mn). , 0 ⁇ x ⁇ 2), and a method for producing a negative thermal expansion material, including a step of preparing an aqueous solution containing a raw material of a compound represented by 0 ⁇ x ⁇ 2) and an organic acid.
  • a negative thermal expansion material having a negative linear expansion coefficient whose absolute value is larger than that of ⁇ -Cu 2 V 2 O 7 in which Cu is not substituted by R is easy to handle at low temperature.
  • Cu 2 ⁇ x R x V 2 ⁇ y My O 7 (R is at least one element selected from Zn, Ga, Fe, Sn, and Mn, M is at least one element selected from Mg, Si, Al, Ti, Cr, Mn, Fe, Co, Ni and Sn, and a raw material of a compound represented by 0 ⁇ x ⁇ 2, 0 ⁇ y ⁇ 2) It is a manufacturing method of a negative thermal expansion material including a step of preparing an aqueous solution containing an organic acid.
  • a negative linear expansion coefficient whose absolute value is larger than that of ⁇ -Cu 2 V 2 O 7 in which Cu is not replaced by R and V is not replaced by M is negative.
  • the thermal expansion material can be manufactured relatively inexpensively by using the form of an aqueous solution which is easy to handle at low temperature.
  • the above-mentioned manufacturing method may include a step of forming a powder of an organic acid salt by granulating by a spray dry method using an aqueous solution. Further, the above-described manufacturing method may include a step of granulating an organic acid salt powder by a freeze drying method using an aqueous solution. This makes it possible to produce the organic acid salt powder without requiring excessive energy such as granulation or pulverization at high temperature or an expensive device.
  • the above-mentioned manufacturing method may include a step of heating the powder of the organic acid salt to decompose the organic acid, and a step of firing the powder in which the organic acid is decomposed to generate an oxide sintered body.
  • the above-mentioned production method may include a step of adding polyethylene glycol to the aqueous solution to form a gel. This enables the generation of finer crystal grains.
  • the above-described manufacturing method may include a step of heating the gel to decompose the organic acid, and a step of firing the powder generated by decomposing the organic acid of the gel to produce an oxide fired body.
  • the organic acid may be citric acid or acetic acid. Further, other substances such as nitric acid may be used as long as they are organic acids in which the raw material of the compound is easily dispersed as an aqueous solution.
  • R may be Zn.
  • M may be Si or Mn. This gives a stable ⁇ -phase (monoclinic) crystal structure at room temperature.
  • X in the general formula (1) may be 0.15 to 1.
  • x may be 0.15-0.5, more preferably 0.15-0.3.
  • y in the general formula (2) may be 0.05 to 0.5.
  • y may be 0.07 to 0.3, more preferably 0.08 to 0.2.
  • the oxide sintered body may have a monoclinic ⁇ phase.
  • the negative thermal expansion material produced by the above method may have a linear expansion coefficient of -7 ppm / K or less in the temperature range of 300 to 500K.
  • Reference Example 1 a polycrystalline sintered body (ceramics) sample of ⁇ -Cu 2 V 2 O 7 and ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 was prepared by using the solid-phase reaction method. Specifically, CuO, ZnO, and V 2 O 5 powders weighed in a stoichiometric ratio were mixed in a mortar and heated in the air at a temperature of 873 to 953K for 10 hours. The obtained powder was sintered using a spark plasma sintering (SPS) furnace (manufactured by SPS Syntex Co., Ltd.) to obtain an oxide sintered body. Sintering was performed under vacuum ( ⁇ 10 ⁇ 1 Pa) using a graphite die at 723 K for 5 minutes.
  • SPS spark plasma sintering
  • FIG. 1 is a diagram showing X-ray diffraction patterns of Cu 2 V 2 O 7 containing no Zn and Cu 1.8 Zn 0.2 V 2 O 7 containing Zn.
  • Cu 2 V 2 O 7 in which Cu is not substituted by Zn has an ⁇ -phase (orthorhombic) crystal structure
  • Cu 1.8 Zn in which Cu is partially substituted by Zn 0.2 V 2 O 7 has a ⁇ phase (monoclinic) crystal structure.
  • the ⁇ phase that does not exist stably in the composition of Cu 2 V 2 O 7 is not stable unless it is at a high temperature (977 K or higher). It can exist stably at room temperature.
  • FIG. 2 is a diagram showing the thermal expansion characteristics of ⁇ -Cu 2 V 2 O 7 and ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 .
  • the vertical axis represents the volume change ⁇ V / V based on the volume V of 100K.
  • the volume change is calculated using the linear expansion coefficient ⁇ calculated using a laser thermal expansion system (LIX-2: manufactured by ULVAC, Inc.) (measurement temperature range 100 to 700K).
  • Table 1 shows the respective crystal structures of ⁇ -Cu 2 V 2 O 7 and ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 , the coefficient of body expansion ⁇ , the range of negative thermal expansion ⁇ T (K), and the volume. Each value of the total change amount ⁇ V / V (%) is described.
  • the total volume change ⁇ V / V of ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 is 2.6%, which is three times or more the total volume change of ⁇ -Cu 2 V 2 O 7 . It can be seen that the material has a large negative thermal expansion.
  • the absolute value of the linear expansion coefficient starts to decrease from around 600K, but in ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 , it reaches 700K. The coefficient of linear expansion is almost constant.
  • FIG. 3 is a view showing a scanning electron microscope (SEM) photograph of ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 produced by using the solid phase reaction method.
  • FIG. 4 is a diagram showing thermal expansion characteristics of an oxide sintered body represented by ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 manufactured by various methods / conditions.
  • ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 according to Reference Example 1 is a negative thermal expansion material in which crystal grains having a size of about 8 to 20 ⁇ m are aggregated. Further, the negative thermal expansion material made of ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 manufactured by using the solid-phase reaction method has a temperature range of 100 to 500 K, as shown by a line L1 in FIG. The linear expansion coefficient is about -14.4 ppm / K.
  • Example 1 a ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 polycrystalline sintered body (ceramics) sample was prepared by using a spray dry method. Specifically, powders of CuO, ZnO, and V 2 O 5 (all having a purity of 99.9%) weighed in a stoichiometric ratio were mixed in a mortar, and baked in the air at a temperature of 943K for 10 hours. The obtained powder is ground in a mortar and dissolved in pure water together with citric acid. At that time, 3 g of anhydrous citric acid and about 100 ml of pure water were added to 1 g of the sample powder, and the mixture was stirred with a magnetic stirrer until all the sample powder was dissolved. Note that V 2 O 3 may be used in addition to or instead of V 2 O 5 .
  • the obtained aqueous solution is dried with a spray dryer and granulated to obtain a citrate powder.
  • This powder is put into an alumina crucible and heated in the atmosphere at 673 K for 5 hours to decompose citric acid.
  • the obtained product is well crushed in a mortar, molded into pellets, placed in an alumina crucible, and fired in an atmosphere of 853 to 943K in the atmosphere for 2 to 10 hours.
  • FIG. 5 is a view showing a scanning electron microscope (SEM) photograph of ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 manufactured by using the spray dry method.
  • SEM scanning electron microscope
  • ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 according to Example 1 is a negative thermal expansion material in which crystal grains with a size of about 3 to 5 ⁇ m are aggregated (note that As described later, according to the accurate particle size distribution using the laser diffraction / scattering type particle size distribution evaluation method, the volume frequency central particle size is 2.7 ⁇ m.).
  • the negative thermal expansion material composed of ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 manufactured by using the spray dry method is line L2 (firing condition 893K / 5h) and line L3 (firing condition in FIG. 4). 853K / 4h) and line L4 (firing condition 893K / 2h), the coefficient of linear expansion is about -7 to -14 ppm / K in the temperature range of 300 to 500K.
  • spray drying ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 prepared using, by optimizing the sintering condition was prepared using a solid-phase reaction method beta-Cu 1 It is possible to obtain a large linear expansion coefficient equivalent to that of 0.8 Zn 0.2 V 2 O 7 and at least a linear expansion coefficient equal to or higher than that of conventionally known ⁇ -Cu 2 V 2 O 7. it can.
  • the aqueous solution containing the raw material of the compound represented by the general formula (1) Cu 2 ⁇ x Zn x V 2 O 7 and the organic acid is prepared.
  • a negative thermal expansion material having a negative linear expansion coefficient whose absolute value is larger than that of ⁇ -Cu 2 V 2 O 7 in which Cu is not substituted by Zn is easy to handle at low temperature.
  • the above-mentioned manufacturing method includes a step of drying and granulating with an aqueous solution by a spray drying method to produce a powder of an organic acid salt. This makes it possible to produce the organic acid salt powder without requiring excessive energy such as granulation or pulverization at high temperature or an expensive device.
  • the above-mentioned manufacturing method includes a step of heating the powder of the organic acid salt to decompose the organic acid, and a step of firing the powder in which the organic acid is decomposed to generate an oxide sintered body. There is. As a result, an oxide sintered body having a desired shape can be produced with relatively low energy.
  • substitution amount x of the substitution element Zn of Cu 2 ⁇ x Zn x V 2 O 7 is 0.15 to 1, at least in the temperature range of 100 to 500 K, it is more preferable than ⁇ -Cu 2 V 2 O 7 A large negative thermal expansion is seen.
  • Zn, Ga, Fe, Sn, and Mn are suitable as the R substituting element in the compound represented by the general formula Cu 2-x R x V 2 O 7 , and Cu 2-x Zn x V It is considered that a linear expansion coefficient equivalent to that of 2 O 7 can be obtained.
  • the substitution elements Zn, Ga, Fe, Sn, and Mn may be substituted not only at the Cu site but also at the V site.
  • Reference Example 2 a polycrystalline sintered body (ceramics) sample of ⁇ -Cu 2 V 2 O 7 was prepared by using the sol-gel method. Specifically, Cu (NO 3 ) 2 3H 2 O is dissolved in pure water, V 2 O 5 is dissolved in citric acid, and these two solutions are mixed and stirred at room temperature for 2 hours. The stirred mixed liquid and polyethylene glycol (polymerization degree: 500,000) are added to a beaker at a mass ratio of 95: 5, and the periphery of the beaker is dissolved while being immersed in water at 80 ° C. (1.5 h). Then, when all of the polyethylene glycol is melted, the periphery of the beaker is immersed in ice water and rapidly cooled to form a gel. Note that V 2 O 3 may be used in addition to or instead of V 2 O 5 .
  • the obtained powder was taken out of the electric furnace and mixed with an agate mortar and pestle for about 30 minutes.
  • the mixed powder was formed into pellets, placed in an alumina crucible, and sintered at 873 to 923K (600 to 650 ° C) for 5 hours.
  • FIG. 6 is a view showing a scanning electron microscope (SEM) photograph of ⁇ -Cu 2 V 2 O 7 manufactured by using the sol-gel method.
  • SEM scanning electron microscope
  • Example 2 a ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 polycrystalline sintered body (ceramics) sample was prepared by using the same sol-gel method as in Reference Example 2.
  • the main difference in Example 2 is that a compound containing zinc (for example, ZnO) is used as a raw material. Therefore, the specific manufacturing method is as described in Reference Example 1, and the specific description is omitted.
  • FIG. 7 is a view showing a scanning electron microscope (SEM) photograph of ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 produced by using the sol-gel method.
  • SEM scanning electron microscope
  • the manufacturing method using the sol-gel method includes the step of adding a polyethylene glycol to an aqueous solution to generate a gel. This makes it possible to generate finer crystal grains than those produced by the spray dry method.
  • Example 3 a polycrystalline sintered body (ceramics) sample of ⁇ -Cu 1.8 Zn 0.2 V 1.9 Si 0.1 O 7 was prepared by using a spray dry method. Specifically, powders of CuO, ZnO, SiO 2 and V 2 O 5 (each having a purity of 99.9%) weighed in a stoichiometric ratio were mixed in a mortar and baked in the atmosphere at a temperature of 943K for 10 hours. .. The obtained powder is ground in a mortar and dissolved in pure water together with citric acid.
  • Example 4 a polycrystalline sintered body (ceramics) sample of ⁇ -Cu 1.8 Zn 0.2 V 1.9 Mn 0.1 O 7 was prepared by using the spray dry method. Specifically, powders of CuO, ZnO, Mn 2 O 3 and V 2 O 5 (each having a purity of 99.9%) weighed in a stoichiometric ratio are mixed in a mortar, and the mixture is mixed in the atmosphere at a temperature of 943K for 10 hours. Baked. The obtained powder is ground in a mortar and dissolved in pure water together with citric acid.
  • Crystal grains in negative thermal expansion material Next, the size of the crystal grains forming the negative thermal expansion material according to the example will be described.
  • the particle size distribution was measured by a laser diffraction / scattering particle size distribution evaluation method.
  • FIG. 8A is a diagram showing the relationship between the particle size and the volume frequency of the negative thermal expansion material according to Example 3, and FIG. 8B is the particle size and volume of the negative thermal expansion material according to Example 4.
  • FIG. 8C is a diagram showing the relationship with the frequency
  • FIG. 8C is a diagram showing the relationship between the particle size and the volume frequency of the negative thermal expansion material according to Example 1.
  • FIG. 9 is a diagram showing X-ray diffraction patterns of the negative thermal expansion materials according to Example 3, Example 4, and Example 1. As shown in FIG. 9, it can be seen that the negative thermal expansion materials according to Example 3 and Example 4 are monoclinic ⁇ -phase, like the negative thermal expansion materials according to Example 1.
  • ⁇ -Cu 1.8 Zn 0.2 V 1.9 Si 0.1 O 7 according to Example 3 has a volume frequency central particle diameter of about 4.0 ⁇ m. It is a negative thermal expansion material in which a large number of crystal grains are aggregated.
  • ⁇ -Cu 1.8 Zn 0.2 V 1.9 Mn 0.1 O 7 according to Example 4 has a volume frequency central particle diameter of about 4.1 ⁇ m. It is a negative thermal expansion material in which a large number of crystal grains are aggregated.
  • FIG. 8C in ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 according to Example 1, a large number of crystal grains having a volume frequency center particle diameter of about 2.7 ⁇ m aggregated. It is a negative thermal expansion material.
  • the above-described manufacturing method includes a step of heating the gel to decompose the organic acid, and a step of firing the powder generated by decomposing the organic acid of the gel to produce an oxide fired body. There is. As a result, an oxide sintered body having a desired shape can be produced with relatively low energy.
  • organic acid used in each example may be acetic acid instead of citric acid.
  • other substances such as nitric acid may be used as long as they are organic acids in which the raw material of the compound is easily dispersed as an aqueous solution.
  • FIG. 10A is a diagram schematically showing crystal grains in an SEM photograph
  • FIG. 10B is a diagram showing internal structures of crystal grains
  • FIG. 10C is a mechanism of negative thermal expansion. It is a figure for explaining.
  • the oxide polycrystalline sintered body is formed by stacking a plurality of agglomerates having a diameter of several ⁇ m to several tens of ⁇ m. Further, as shown in FIG. 10B, the agglomerate is an aggregate of a plurality of crystal grains CG, and voids AS are formed between the crystal grains CG.
  • the negative thermal expansion of the crystal does not necessarily change isotropically in magnitude.
  • ⁇ -Cu 1.8 Zn 0.2 V 2 O 7 when the temperature rises from low temperature TL to high temperature TH (> TL), it shrinks in the a-axis and c-axis directions of the unit cell of the crystal, It extends in the direction of the b-axis. Therefore, if there is a void in the b-axis direction, it is considered that the void absorbs the extension of the crystal in the b-axis direction, so that the negative thermal expansion of the sintered body as a whole becomes large.
  • the negative thermal expansion material manufactured by the manufacturing method according to the embodiment of the present disclosure has a substantially constant linear expansion coefficient with respect to temperature change in a wide temperature range of about 100 to 500K, Material functional design is easy. Further, there are industrial merits such as being mainly composed of inexpensive elements such as Cu, Zn, and V, being an oxide, having a low synthesis temperature, being easy to manufacture, and being able to obtain fine particles. Further, a manufacturing method such as a spray dry method or a sol-gel method according to the present embodiment is different from the pulverization method, and a new negative thermal expansion material having a desired shape can be manufactured without destroying a tissue expressing negative thermal expansion. That's the method.
  • precision optical parts and mechanical parts that do not want to change shape and dimensions due to temperature, process equipment and tools, temperature compensating materials for fiber gratings, printed circuit boards, sealing materials for electronic parts, thermal switches, refrigerator parts. It can be used for artificial satellite parts.
  • a composite material in which a negative thermal expansion material is dispersed in a matrix phase of a resin having a large positive coefficient of thermal expansion it is possible to suppress and control the thermal expansion of the resin material as well, so that various applications can be achieved. Can be used in.
  • the particle size is small, it is possible to control the thermal expansion of the local region of the micrometer level, and for example, it can be used for the thermal expansion control inside the electronic device.
  • the negative thermal expansion material having a small particle size can be widely used in industry.

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Abstract

This method for producing a negative thermal expansion material of one embodiment comprises a step for preparing an aqueous solution containing an organic acid and the starting materials for a compound represented by general formula (1) Cu2-xRxV2O7 (where: R is at least one element selected from Zn, Ga, Fe, Sn, and Mn; and 0 ≤ x < 2).

Description

負熱膨張材料の製造方法Method for manufacturing negative thermal expansion material 関連出願の相互参照Cross-reference of related applications
　本出願は、２０１８年１１月９日に出願された日本国特許出願２０１８－２１１６１９号に基づくものであって、その優先権の利益を主張するものであり、その特許出願の全ての内容が、参照により本明細書に組み込まれる。 This application is based on Japanese Patent Application No. 2018-211619 filed on November 9, 2018, and claims the benefit of its priority, and the entire contents of the patent application are Incorporated herein by reference.
　本発明は、負熱膨張材料に関する。 The present invention relates to a negative thermal expansion material.
　一般的に、物質は温度上昇に伴って熱膨張することが知られている。しかしながら、近年における産業技術の高度な発達は、固体材料の宿命とも言える熱膨張すら制御することを求める。長さ変化率にして１０ｐｐｍ（１０－５）程度の、一般的な感覚からすればわずかな変化でも、ナノメートルレベルの高精度が求められる半導体デバイス製造や、部品のわずかな歪が機能に大きな影響を与える精密機器などの分野では大きな問題である。また、複数の素材を組み合わせたデバイスでは、構成素材それぞれの熱膨張の違いから、界面剥離や断線といった他の問題も生じることがある。 It is generally known that a substance thermally expands as the temperature rises. However, the advanced development of industrial technology in recent years requires that even thermal expansion, which is the fate of solid materials, be controlled. Even if it is a slight change from the general sense, the rate of change in length is about 10 ppm (10 −5 ), semiconductor device manufacturing that requires high precision at the nanometer level and slight distortion of parts have a large function. It is a big problem in the field of precision instruments that influences. Further, in a device in which a plurality of materials are combined, other problems such as interfacial peeling and disconnection may occur due to the difference in thermal expansion of each constituent material.
　一方、温度上昇に伴って格子体積が減少する（負の熱膨張率を持った）負熱膨張材料も知られている。例えば、負の熱膨張率を有するα－Ｃｕ２Ｖ２Ｏ７と正の熱膨張率を有するＡｌとを混合することで熱膨張を抑制する複合材料が知られている（非特許文献１）。また、Ｃｕ２Ｖ２Ｏ７のＣｕの一部をＺｎで置換したβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７ではさらに大きな負の熱膨張率を有することが知られる（非特許文献２）。 On the other hand, a negative thermal expansion material whose lattice volume decreases (has a negative coefficient of thermal expansion) with an increase in temperature is also known. For example, a composite material that suppresses thermal expansion by mixing α-Cu 2 V 2 O 7 having a negative coefficient of thermal expansion with Al having a positive coefficient of thermal expansion is known (Non-Patent Document 1). .. Further, β-Cu 1.8 Zn 0.2 V 2 O 7 in which a part of Cu in Cu 2 V 2 O 7 is replaced with Zn is known to have a larger negative thermal expansion coefficient (Non-Patent Document 1). 2).
　α－Ｃｕ２Ｖ２Ｏ７は、線膨張係数にして－５～－６ｐｐｍ／℃の負熱膨張を、室温から２００℃の温度域で発現することが知られている。しかしながら、α－Ｃｕ２Ｖ２Ｏ７の線膨張係数の大きさや負熱膨張を示す温度範囲については改善の余地がある。また、β－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７では線膨張係数にして－１４．４ｐｐｍ／℃の負熱膨張を、－１７３℃から４２７℃の広い温度域で発現することが知られている。一方で、負熱膨張材料の利用を促進するためには、負の線膨張係数の大きさだけでなく、その形状や製造にかかるコストも重要である。とりわけ、粒径が小さく揃った負熱膨張材料粉末は、射出成形を行う樹脂材料はじめ、他の材料との複合化や微小部材への適用が可能となるため、利用価値が極めて高い。 It is known that α-Cu 2 V 2 O 7 exhibits a negative thermal expansion of −5 to −6 ppm / ° C. as a linear expansion coefficient in a temperature range of room temperature to 200 ° C. However, there is room for improvement in the magnitude of the linear expansion coefficient of α-Cu 2 V 2 O 7 and the temperature range in which negative thermal expansion is exhibited. It is also known that β-Cu 1.8 Zn 0.2 V 2 O 7 exhibits negative thermal expansion of -14.4 ppm / ° C in linear expansion coefficient in a wide temperature range of -173 ° C to 427 ° C. Has been. On the other hand, in order to promote the use of the negative thermal expansion material, not only the magnitude of the negative linear expansion coefficient, but also the shape and the manufacturing cost are important. In particular, the negative thermal expansion material powder having a small particle size can be used as a resin material for injection molding, can be compounded with other materials, and can be applied to minute members, and thus has extremely high utility value.
　特に前述のβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７の負熱膨張は、セラミック粒子特有の材料組織効果に由来すると考えられており、単に粉砕してしまえば、負熱膨張を発現する組織が壊れてしまう。そのため、負熱膨張を示す微粒子を製造するのは容易ではなく、その方法については先に挙げた先行文献でも検討されていない。 In particular, the above-mentioned negative thermal expansion of β-Cu 1.8 Zn 0.2 V 2 O 7 is considered to be derived from the material structure effect peculiar to ceramic particles, and if it is simply pulverized, negative thermal expansion will occur. The organization that you do will break. Therefore, it is not easy to produce fine particles exhibiting negative thermal expansion, and the method has not been examined in the above-mentioned prior documents.
　本開示はこうした状況に鑑みてなされており、その目的とするところの一つは、負熱膨張材料の新たな製造方法を提供することにある。 The present disclosure has been made in view of such circumstances, and one of the aims thereof is to provide a new method for producing a negative thermal expansion material.
　上記課題を解決するために、本開示のある態様の負熱膨張材料の製造方法は、一般式（１）Ｃｕ２－ｘＲｘＶ２Ｏ７（ＲはＺｎ、Ｇａ、Ｆｅ、Ｓｎ、Ｍｎから選ばれる少なくとも１種の元素）で表される化合物の原料と有機酸とを含む水溶液を準備する工程を含む。 In order to solve the above-mentioned problems, a method for producing a negative thermal expansion material according to an aspect of the present disclosure provides a method represented by the general formula (1): Cu 2−x R x V 2 O 7 (R is Zn, Ga, Fe, Sn, Mn). At least one element selected from) and a step of preparing an aqueous solution containing a raw material of a compound represented by the formula and an organic acid.
　本開示によれば、コスト低減に寄与しうる新たな負熱膨張材料の製造方法を提供できる。 According to the present disclosure, it is possible to provide a new negative thermal expansion material manufacturing method that can contribute to cost reduction.
Ｚｎを含まないＣｕ２Ｖ２Ｏ７およびＺｎを含むＣｕ１．８Ｚｎ０．２Ｖ２Ｏ７のＸ線回折パターンを示す図である。Is a diagram showing an X-ray diffraction pattern of Cu 1.8 Zn 0.2 V 2 O 7 containing Cu 2 V 2 O 7, and Zn containing no Zn. α－Ｃｕ２Ｖ２Ｏ７及びβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７の熱膨張特性を示す図である。is a diagram showing the thermal expansion characteristics of the α-Cu 2 V 2 O 7 and β-Cu 1.8 Zn 0.2 V 2 O 7. 固相反応法を用いて製造したβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７の走査型電子顕微鏡（ＳＥＭ）写真を示す図である。Is a diagram showing a scanning electron microscope (SEM) photograph of β-Cu 1.8 Zn 0.2 V 2 O 7 prepared using solid phase reaction method. 各種方法／条件で製造したβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７で表される酸化物焼結体の熱膨張特性を示す図である。FIG. 3 is a diagram showing thermal expansion characteristics of an oxide sintered body represented by β-Cu 1.8 Zn 0.2 V 2 O 7 manufactured by various methods / conditions. スプレードライ法を用いて製造したβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７の走査型電子顕微鏡（ＳＥＭ）写真を示す図である。Is a diagram showing a scanning electron microscope (SEM) photograph of β-Cu 1.8 Zn 0.2 V 2 O 7 prepared by a spray drying method. ゾルゲル法を用いて製造したα－Ｃｕ２Ｖ２Ｏ７の走査型電子顕微鏡（ＳＥＭ）写真を示す図である。Sol-gel method is a diagram showing a scanning electron microscope (SEM) photograph of α-Cu 2 V 2 O 7 was prepared using. ゾルゲル法を用いて製造したβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７の走査型電子顕微鏡（ＳＥＭ）写真を示す図である。Sol-gel method is a diagram showing a scanning electron microscope (SEM) photograph of β-Cu 1.8 Zn 0.2 V 2 O 7 was prepared using. 図８（ａ）は、実施例３に係る負熱膨張材料の粒径と体積頻度との関係を示す図、図８（ｂ）は、実施例４に係る負熱膨張材料の粒径と体積頻度との関係を示す図、図８（ｃ）は、実施例１に係る負熱膨張材料の粒径と体積頻度との関係を示す図である。FIG. 8A is a diagram showing the relationship between the particle size and the volume frequency of the negative thermal expansion material according to Example 3, and FIG. 8B is the particle size and volume of the negative thermal expansion material according to Example 4. FIG. 8C is a diagram showing the relationship with the frequency, and FIG. 8C is a diagram showing the relationship between the particle size and the volume frequency of the negative thermal expansion material according to Example 1. 図９は、実施例３、実施例４および実施例１に係る負熱膨張材料のＸ線回折パターンを示す図である。FIG. 9 is a diagram showing X-ray diffraction patterns of the negative thermal expansion materials according to Example 3, Example 4, and Example 1. 図１０（ａ）は、ＳＥＭ写真における結晶粒を模式的に示した図、図１０（ｂ）は、結晶粒の内部構造を示す図、図１０（ｃ）は、負熱膨張の発現メカニズムを説明するための図である。10A is a diagram schematically showing crystal grains in an SEM photograph, FIG. 10B is a diagram showing internal structures of crystal grains, and FIG. 10C is a mechanism of negative thermal expansion. It is a figure for explaining.
　本発明者らは、負熱膨張が発現する物質の候補として、Ｃｕ２Ｖ２Ｏ７系に注目した。結晶構造が直方晶のα－Ｃｕ２Ｖ２Ｏ７は、強誘電と弱常磁性が共存するマルチフェロイック物質として関心が持たれているが、室温を含むそれより高温側の比較的広い温度域で、誘電不安定性に起因すると思われる、結晶格子の異方的な熱変形が見られる。この結果、広い温度範囲で温度の上昇に伴いユニットセル体積が収縮する負熱膨張が出現する。 The present inventors have focused on the Cu 2 V 2 O 7 system as a candidate for a substance exhibiting negative thermal expansion. Α-Cu 2 V 2 O 7 having a rectangular crystal structure is of interest as a multiferroic substance in which ferroelectricity and weak paramagnetism coexist, but it has a relatively wide temperature range including room temperature and higher temperatures. In the region, anisotropic thermal deformation of the crystal lattice, which is probably due to dielectric instability, is observed. As a result, negative thermal expansion occurs in which the unit cell volume contracts with increasing temperature in a wide temperature range.
　Ｃｕ２Ｖ２Ｏ７は様々な元素で置換することにより、直方晶のα相の他、単斜相のβ相、三斜晶のγ相をとりうる。そこで、本発明者らは、ＣｕサイトやＶサイトの一部を他の元素で置換した場合に、従来のα－Ｃｕ２Ｖ２Ｏ７系では実現し得ない負熱膨張特性を発現することを見出し、以下に例示する負熱膨張材料およびその製造方法を考案した。 By substituting various elements, Cu 2 V 2 O 7 can assume a monoclinic β phase and a triclinic γ phase in addition to the orthorhombic α phase. Therefore, the inventors of the present invention should develop negative thermal expansion characteristics that cannot be realized by the conventional α-Cu 2 V 2 O 7 system, when a part of the Cu site or V site is replaced with another element. The inventors have devised a negative thermal expansion material and a method for producing the same, which are exemplified below.
　上記課題を解決するために、本開示のある態様は、一般式（１）Ｃｕ２－ｘＲｘＶ２Ｏ７（ＲはＺｎ、Ｇａ、Ｆｅ、Ｓｎ、Ｍｎから選ばれる少なくとも１種の元素、０≦ｘ＜２）で表される化合物の原料と有機酸とを含む水溶液を準備する工程を含む負熱膨張材料の製造方法である。 In order to solve the above-mentioned problems, one embodiment of the present disclosure is to provide at least one element selected from the general formula (1): Cu 2−x R x V 2 O 7 (R is Zn, Ga, Fe, Sn, Mn). , 0 ≦ x <2), and a method for producing a negative thermal expansion material, including a step of preparing an aqueous solution containing a raw material of a compound represented by 0 ≦ x <2) and an organic acid.
　この態様によると、ＣｕがＲで置換されていないα－Ｃｕ２Ｖ２Ｏ７の線膨張係数よりも絶対値の大きな負の線膨張係数を有する負熱膨張材料を、低温で扱いが容易な水溶液という形態を利用することで、比較的安価に製造できる。 According to this aspect, a negative thermal expansion material having a negative linear expansion coefficient whose absolute value is larger than that of α-Cu 2 V 2 O 7 in which Cu is not substituted by R is easy to handle at low temperature. By using the form of an aqueous solution, it can be manufactured relatively inexpensively.
　また、本開示の他の態様は、一般式（２）Ｃｕ２－ｘＲｘＶ２－ｙＭｙＯ７（ＲはＺｎ、Ｇａ、Ｆｅ、Ｓｎ、Ｍｎから選ばれる少なくとも１種の元素、ＭはＭｇ、Ｓｉ、Ａｌ、Ｔｉ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｓｎから選ばれる少なくとも１種の元素、０≦ｘ＜２、０＜ｙ＜２）で表される化合物の原料と有機酸とを含む水溶液を準備する工程を含む負熱膨張材料の製造方法である。 In addition, another embodiment of the present disclosure is that Cu 2−x R x V 2− y My O 7 (R is at least one element selected from Zn, Ga, Fe, Sn, and Mn, M is at least one element selected from Mg, Si, Al, Ti, Cr, Mn, Fe, Co, Ni and Sn, and a raw material of a compound represented by 0 ≦ x <2, 0 <y <2) It is a manufacturing method of a negative thermal expansion material including a step of preparing an aqueous solution containing an organic acid.
　この態様によると、ＣｕがＲで置換されていない、また、ＶがＭで置換されていないα－Ｃｕ２Ｖ２Ｏ７の線膨張係数よりも絶対値の大きな負の線膨張係数を有する負熱膨張材料を、低温で扱いが容易な水溶液という形態を利用することで、比較的安価に製造できる。 According to this aspect, a negative linear expansion coefficient whose absolute value is larger than that of α-Cu 2 V 2 O 7 in which Cu is not replaced by R and V is not replaced by M is negative. The thermal expansion material can be manufactured relatively inexpensively by using the form of an aqueous solution which is easy to handle at low temperature.
　上述の製造方法は、水溶液を用いてスプレードライ法により造粒し、有機酸塩の粉末を生成する工程を含んでもよい。また、上述の製造方法は、水溶液を用いてフリーズドライ法により造粒し、有機酸塩の粉末を生成する工程を含んでもよい。これにより、高温での造粒や粉砕といった過大なエネルギーや高価な装置を必要とせずに有機酸塩の粉末を製造できる。 The above-mentioned manufacturing method may include a step of forming a powder of an organic acid salt by granulating by a spray dry method using an aqueous solution. Further, the above-described manufacturing method may include a step of granulating an organic acid salt powder by a freeze drying method using an aqueous solution. This makes it possible to produce the organic acid salt powder without requiring excessive energy such as granulation or pulverization at high temperature or an expensive device.
　上述の製造方法は、有機酸塩の粉末を加熱し、有機酸を分解する工程と、有機酸が分解された粉末を焼成して酸化物焼結体を生成する工程と、を含んでもよい。これにより、比較的低エネルギーで所望の形状の酸化物焼結体を生成できる。 The above-mentioned manufacturing method may include a step of heating the powder of the organic acid salt to decompose the organic acid, and a step of firing the powder in which the organic acid is decomposed to generate an oxide sintered body. As a result, an oxide sintered body having a desired shape can be produced with relatively low energy.
　上述の製造方法は、水溶液にポリエチレングリコールを加えてゲルを生成する工程を含んでもよい。これにより、より微細な結晶粒の生成が可能となる。 The above-mentioned production method may include a step of adding polyethylene glycol to the aqueous solution to form a gel. This enables the generation of finer crystal grains.
　上述の製造方法は、ゲルを加熱し、有機酸を分解する工程と、ゲルの有機酸が分解されて生成された粉末を焼成して酸化物焼成体を生成する工程と、を含んでもよい。これにより、比較的低エネルギーで所望の形状の酸化物焼結体を生成できる。 The above-described manufacturing method may include a step of heating the gel to decompose the organic acid, and a step of firing the powder generated by decomposing the organic acid of the gel to produce an oxide fired body. As a result, an oxide sintered body having a desired shape can be produced with relatively low energy.
　有機酸は、クエン酸または酢酸であってもよい。また、水溶液として化合物の原料が分散しやすい有機酸であれば、硝酸などの他の物質であってもよい。 The organic acid may be citric acid or acetic acid. Further, other substances such as nitric acid may be used as long as they are organic acids in which the raw material of the compound is easily dispersed as an aqueous solution.
　ＲはＺｎであってもよい。また、ＭはＳｉまたはＭｎであってもよい。これにより、室温で安定したβ相（単斜相）の結晶構造が得られる。 R may be Zn. Further, M may be Si or Mn. This gives a stable β-phase (monoclinic) crystal structure at room temperature.
　一般式（１）におけるｘは、０．１５～１であってもよい。好ましくは、ｘは０．１５～０．５、より好ましくは０．１５～０．３であってもよい。これにより、ＣｕがＲで置換されていないα－Ｃｕ２Ｖ２Ｏ７の線膨張係数よりも絶対値の大きな線膨張係数を実現できる。 X in the general formula (1) may be 0.15 to 1. Preferably, x may be 0.15-0.5, more preferably 0.15-0.3. Thereby, a linear expansion coefficient having an absolute value larger than that of α-Cu 2 V 2 O 7 in which Cu is not substituted by R can be realized.
　また、一般式（２）におけるｙは、０．０５～０．５であってもよい。好ましくは、ｙは０．０７～０．３、より好ましくは０．０８～０．２であってもよい。これにより、ＶがＭで置換されていないα－Ｃｕ２Ｖ２Ｏ７の線膨張係数よりも絶対値の大きな線膨張係数を実現できる。 Further, y in the general formula (2) may be 0.05 to 0.5. Preferably y may be 0.07 to 0.3, more preferably 0.08 to 0.2. As a result, a linear expansion coefficient having a larger absolute value than that of α-Cu 2 V 2 O 7 in which V is not replaced by M can be realized.
　酸化物焼結体は、単斜晶のβ相であってもよい。 The oxide sintered body may have a monoclinic β phase.
　上述の方法で製造された負熱膨張材料は、３００～５００Ｋの温度範囲において線膨張係数が－７ｐｐｍ／Ｋ以下であってもよい。 The negative thermal expansion material produced by the above method may have a linear expansion coefficient of -7 ppm / K or less in the temperature range of 300 to 500K.
　以下、図面等を参照しながら、本開示を実施するための形態について詳細に説明する。 Hereinafter, modes for carrying out the present disclosure will be described in detail with reference to the drawings and the like.
　［参考例１］
　参考例１では、固相反応法を用いてα－Ｃｕ２Ｖ２Ｏ７及びβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７の多結晶焼結体（セラミックス）試料を作製した。具体的には、化学量論比で秤量したＣｕＯ、ＺｎＯ及びＶ２Ｏ５の粉末を乳鉢で混合し、温度８７３～９５３Ｋの大気中で１０時間加熱した。得られた粉末を、スパークプラズマ焼結（ＳＰＳ）炉（ＳＰＳシンテックス株式会社製）を用いて焼結し、酸化物焼結体を得た。焼結は、真空（＜１０－１Ｐａ）下、グラファイトダイを用いて７２３Ｋで５分間行った。 [Reference Example 1]
In Reference Example 1, a polycrystalline sintered body (ceramics) sample of α-Cu 2 V 2 O 7 and β-Cu 1.8 Zn 0.2 V 2 O 7 was prepared by using the solid-phase reaction method. Specifically, CuO, ZnO, and V 2 O 5 powders weighed in a stoichiometric ratio were mixed in a mortar and heated in the air at a temperature of 873 to 953K for 10 hours. The obtained powder was sintered using a spark plasma sintering (SPS) furnace (manufactured by SPS Syntex Co., Ltd.) to obtain an oxide sintered body. Sintering was performed under vacuum (<10 −1 Pa) using a graphite die at 723 K for 5 minutes.
　その後、それぞれの試料を粉末Ｘ線回折（ＸＲＤ）法（測定温度２９５Ｋ、ＣｕＫαの特性Ｘ線：波長λ＝０．１５４１８ｎｍ）および放射光温度変化Ｘ線回折法（波長λ＝０．０６５２１ｎｍ）を用いて結晶構造を評価した。図１は、Ｚｎを含まないＣｕ２Ｖ２Ｏ７およびＺｎを含むＣｕ１．８Ｚｎ０．２Ｖ２Ｏ７のＸ線回折パターンを示す図である。 Then, each sample was subjected to powder X-ray diffraction (XRD) method (measurement temperature 295K, characteristic X-ray of CuKα: wavelength λ = 0.15418 nm) and synchrotron radiation X-ray diffraction method (wavelength λ = 0.06521 nm). Was used to evaluate the crystal structure. FIG. 1 is a diagram showing X-ray diffraction patterns of Cu 2 V 2 O 7 containing no Zn and Cu 1.8 Zn 0.2 V 2 O 7 containing Zn.
　図１に示すように、ＺｎでＣｕが置換されてないＣｕ２Ｖ２Ｏ７は結晶構造がα相（直方晶）であり、ＺｎでＣｕの一部が置換されているＣｕ１．８Ｚｎ０．２Ｖ２Ｏ７は結晶構造がβ相（単斜晶）である。このように、Ｃｕ２Ｖ２Ｏ７の一部の元素を他の元素で置換することで、Ｃｕ２Ｖ２Ｏ７の組成では高温（９７７Ｋ以上）でなければ安定して存在しないβ相が、室温で安定して存在できる。 As shown in FIG. 1, Cu 2 V 2 O 7 in which Cu is not substituted by Zn has an α-phase (orthorhombic) crystal structure, and Cu 1.8 Zn in which Cu is partially substituted by Zn 0.2 V 2 O 7 has a β phase (monoclinic) crystal structure. As described above, by substituting a part of the elements of Cu 2 V 2 O 7 with other elements, the β phase that does not exist stably in the composition of Cu 2 V 2 O 7 is not stable unless it is at a high temperature (977 K or higher). It can exist stably at room temperature.
　図２は、α－Ｃｕ２Ｖ２Ｏ７及びβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７の熱膨張特性を示す図である。縦軸は１００Ｋの体積Ｖを基準とした体積変化ΔＶ／Ｖである。体積変化は、レーザー熱膨張系（ＬＩＸ－２：株式会社アルバック製）を用いて算出した線膨張係数αを用いて算出している（測定温度範囲１００～７００Ｋ）。表１に、α－Ｃｕ２Ｖ２Ｏ７及びβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７のそれぞれの結晶構造、体膨張係数β、負熱膨張の発現範囲ΔＴ（Ｋ）、体積変化総量ΔＶ／Ｖ（％）の各値を記載した。 FIG. 2 is a diagram showing the thermal expansion characteristics of α-Cu 2 V 2 O 7 and β-Cu 1.8 Zn 0.2 V 2 O 7 . The vertical axis represents the volume change ΔV / V based on the volume V of 100K. The volume change is calculated using the linear expansion coefficient α calculated using a laser thermal expansion system (LIX-2: manufactured by ULVAC, Inc.) (measurement temperature range 100 to 700K). Table 1 shows the respective crystal structures of α-Cu 2 V 2 O 7 and β-Cu 1.8 Zn 0.2 V 2 O 7 , the coefficient of body expansion β, the range of negative thermal expansion ΔT (K), and the volume. Each value of the total change amount ΔV / V (%) is described.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１に示すように、β－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７は、体膨張係数β（＝３α）の絶対値がα－Ｃｕ２Ｖ２Ｏ７の体膨張係数の絶対値の２．５倍以上である。また、β－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７の体積変化総量ΔＶ／Ｖは２．６％であり、α－Ｃｕ２Ｖ２Ｏ７の体積変化総量の３倍以上であり、大きな負熱膨張を示す材料であることがわかる。また、α－Ｃｕ２Ｖ２Ｏ７では、６００Ｋを超えたあたりから線膨張係数の絶対値が減少し始めているが、β－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７では、７００Ｋに至っても線膨張係数はほぼ一定である。 As shown in Table 1, in β-Cu 1.8 Zn 0.2 V 2 O 7 , the absolute value of the body expansion coefficient β (= 3α) is α-Cu 2 V 2 O 7 in absolute value. Is more than 2.5 times. The total volume change ΔV / V of β-Cu 1.8 Zn 0.2 V 2 O 7 is 2.6%, which is three times or more the total volume change of α-Cu 2 V 2 O 7 . It can be seen that the material has a large negative thermal expansion. In addition, in α-Cu 2 V 2 O 7 , the absolute value of the linear expansion coefficient starts to decrease from around 600K, but in β-Cu 1.8 Zn 0.2 V 2 O 7 , it reaches 700K. The coefficient of linear expansion is almost constant.
　図３は、固相反応法を用いて製造したβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７の走査型電子顕微鏡（ＳＥＭ）写真を示す図である。図４は、各種方法／条件で製造したβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７で表される酸化物焼結体の熱膨張特性を示す図である。 FIG. 3 is a view showing a scanning electron microscope (SEM) photograph of β-Cu 1.8 Zn 0.2 V 2 O 7 produced by using the solid phase reaction method. FIG. 4 is a diagram showing thermal expansion characteristics of an oxide sintered body represented by β-Cu 1.8 Zn 0.2 V 2 O 7 manufactured by various methods / conditions.
　図３に示すように、参考例１に係るβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７は、大きさが８～２０μｍ程度の結晶粒が凝集した負熱膨張材料である。また、固相反応法を用いて製造したβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７からなる負熱膨張材料は、図４のラインＬ１に示すように、１００～５００Ｋの温度範囲において線膨張係数が－１４．４ｐｐｍ／Ｋ程度である。 As shown in FIG. 3, β-Cu 1.8 Zn 0.2 V 2 O 7 according to Reference Example 1 is a negative thermal expansion material in which crystal grains having a size of about 8 to 20 μm are aggregated. Further, the negative thermal expansion material made of β-Cu 1.8 Zn 0.2 V 2 O 7 manufactured by using the solid-phase reaction method has a temperature range of 100 to 500 K, as shown by a line L1 in FIG. The linear expansion coefficient is about -14.4 ppm / K.
　［実施例１］
　実施例１では、スプレードライ法を用いてβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７の多結晶焼結体（セラミックス）試料を作製した。具体的には、化学量論比で秤量したＣｕＯ、ＺｎＯ及びＶ２Ｏ５（いずれも純度９９．９％）の粉末を乳鉢で混合し、温度９４３Ｋの大気中で１０時間焼成した。得られた粉末を、乳鉢ですりつぶし、クエン酸とともに純水に溶かす。その際、試料粉末１ｇに対して無水クエン酸３ｇ、純水約１００ｍｌを加え、試料粉末が全て溶けるまでマグネティックスターラーを用いて撹拌する。なお、Ｖ２Ｏ５に加えてまたは代わりにＶ２Ｏ３を用いてもよい。 [Example 1]
In Example 1, a β-Cu 1.8 Zn 0.2 V 2 O 7 polycrystalline sintered body (ceramics) sample was prepared by using a spray dry method. Specifically, powders of CuO, ZnO, and V 2 O 5 (all having a purity of 99.9%) weighed in a stoichiometric ratio were mixed in a mortar, and baked in the air at a temperature of 943K for 10 hours. The obtained powder is ground in a mortar and dissolved in pure water together with citric acid. At that time, 3 g of anhydrous citric acid and about 100 ml of pure water were added to 1 g of the sample powder, and the mixture was stirred with a magnetic stirrer until all the sample powder was dissolved. Note that V 2 O 3 may be used in addition to or instead of V 2 O 5 .
　その後、得られた水溶液をスプレードライヤーにより乾燥、造粒し、クエン酸塩の粉末を得る。この粉末をアルミナルツボに入れ、大気中で６７３Ｋ、５時間加熱してクエン酸を分解する。得られたものを乳鉢でよく砕き、ペレット状に成型し、アルミナルツボに入れ、電気炉を用いて８５３～９４３Ｋの大気中で、２～１０時間焼成する。 After that, the obtained aqueous solution is dried with a spray dryer and granulated to obtain a citrate powder. This powder is put into an alumina crucible and heated in the atmosphere at 673 K for 5 hours to decompose citric acid. The obtained product is well crushed in a mortar, molded into pellets, placed in an alumina crucible, and fired in an atmosphere of 853 to 943K in the atmosphere for 2 to 10 hours.
　図５は、スプレードライ法を用いて製造したβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７の走査型電子顕微鏡（ＳＥＭ）写真を示す図である。図５に示すように、実施例１に係るβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７は、大きさが３～５μｍ程度の結晶粒が凝集した負熱膨張材料である（なお、後述するように、レーザー回折／散乱式粒径分布評価法を用いた正確な粒径分布によれば、体積頻度中心粒径は２．７μｍである。）。また、スプレードライ法を用いて製造したβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７からなる負熱膨張材料は、図４のラインＬ２（焼成条件８９３Ｋ／５ｈ）、ラインＬ３（焼成条件８５３Ｋ／４ｈ）、ラインＬ４（焼成条件８９３Ｋ／２ｈ）に示すように、３００～５００Ｋの温度範囲において線膨張係数が－７～－１４ｐｐｍ／Ｋ程度である。 FIG. 5 is a view showing a scanning electron microscope (SEM) photograph of β-Cu 1.8 Zn 0.2 V 2 O 7 manufactured by using the spray dry method. As shown in FIG. 5, β-Cu 1.8 Zn 0.2 V 2 O 7 according to Example 1 is a negative thermal expansion material in which crystal grains with a size of about 3 to 5 μm are aggregated (note that As described later, according to the accurate particle size distribution using the laser diffraction / scattering type particle size distribution evaluation method, the volume frequency central particle size is 2.7 μm.). Further, the negative thermal expansion material composed of β-Cu 1.8 Zn 0.2 V 2 O 7 manufactured by using the spray dry method is line L2 (firing condition 893K / 5h) and line L3 (firing condition in FIG. 4). 853K / 4h) and line L4 (firing condition 893K / 2h), the coefficient of linear expansion is about -7 to -14 ppm / K in the temperature range of 300 to 500K.
　このように、スプレードライ法を用いて製造したβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７は、焼成条件を最適化することで、固相反応法を用いて製造したβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７と同等の大きな線膨張係数を得ることができ、また、少なくとも従来知られているα－Ｃｕ２Ｖ２Ｏ７と同等以上の線膨張係数を得ることができる。 Thus, spray drying β-Cu 1.8 Zn 0.2 V 2 O 7 prepared using, by optimizing the sintering condition was prepared using a solid-phase reaction method beta-Cu 1 It is possible to obtain a large linear expansion coefficient equivalent to that of 0.8 Zn 0.2 V 2 O 7 and at least a linear expansion coefficient equal to or higher than that of conventionally known α-Cu 2 V 2 O 7. it can.
　前述のように、実施例１に係る負熱膨張材料の製造方法は、一般式（１）Ｃｕ２－ｘＺｎｘＶ２Ｏ７で表される化合物の原料と有機酸とを含む水溶液を準備する工程を含む。この製造方法によると、ＣｕがＺｎで置換されていないα－Ｃｕ２Ｖ２Ｏ７の線膨張係数よりも絶対値の大きな負の線膨張係数を有する負熱膨張材料を、低温で扱いが容易な水溶液という形態を利用することで、比較的安価に製造できる。 As described above, in the method for producing the negative thermal expansion material according to Example 1, the aqueous solution containing the raw material of the compound represented by the general formula (1) Cu 2−x Zn x V 2 O 7 and the organic acid is prepared. Including the step of According to this manufacturing method, a negative thermal expansion material having a negative linear expansion coefficient whose absolute value is larger than that of α-Cu 2 V 2 O 7 in which Cu is not substituted by Zn is easy to handle at low temperature. By using a form of a simple aqueous solution, it can be manufactured at a relatively low cost.
　また、前述の製造方法は、水溶液を用いてスプレードライ法により乾燥、造粒し、有機酸塩の粉末を生成する工程を含んでいる。これにより、高温での造粒や粉砕といった過大なエネルギーや高価な装置を必要とせずに有機酸塩の粉末を製造できる。 Also, the above-mentioned manufacturing method includes a step of drying and granulating with an aqueous solution by a spray drying method to produce a powder of an organic acid salt. This makes it possible to produce the organic acid salt powder without requiring excessive energy such as granulation or pulverization at high temperature or an expensive device.
　また、前述の製造方法は、有機酸塩の粉末を加熱し、有機酸を分解する工程と、有機酸が分解された粉末を焼成して酸化物焼結体を生成する工程と、を含んでいる。これにより、比較的低エネルギーで所望の形状の酸化物焼結体を生成できる。 Further, the above-mentioned manufacturing method includes a step of heating the powder of the organic acid salt to decompose the organic acid, and a step of firing the powder in which the organic acid is decomposed to generate an oxide sintered body. There is. As a result, an oxide sintered body having a desired shape can be produced with relatively low energy.
　また、Ｃｕ２－ｘＺｎｘＶ２Ｏ７の置換元素Ｚｎの置換量ｘは０．１５～１の場合であれば、少なくとも１００～５００Ｋの温度範囲でα－Ｃｕ２Ｖ２Ｏ７よりも大きな負熱膨張が見られる。また、一般式Ｃｕ２－ｘＲｘＶ２Ｏ７で表される化合物におけるＲの置換元素としては、Ｚｎ以外に、ＧａやＦｅ、Ｓｎ、Ｍｎが好適であり、Ｃｕ２－ｘＺｎｘＶ２Ｏ７と同等の線膨張係数が得られると考えられる。また、置換元素であるＺｎ、Ｇａ、Ｆｅ、Ｓｎ、Ｍｎは、Ｃｕサイトだけでなく、Ｖサイトに置換されることもある。 Further, when the substitution amount x of the substitution element Zn of Cu 2−x Zn x V 2 O 7 is 0.15 to 1, at least in the temperature range of 100 to 500 K, it is more preferable than α-Cu 2 V 2 O 7 A large negative thermal expansion is seen. In addition to Zn, Ga, Fe, Sn, and Mn are suitable as the R substituting element in the compound represented by the general formula Cu 2-x R x V 2 O 7 , and Cu 2-x Zn x V It is considered that a linear expansion coefficient equivalent to that of 2 O 7 can be obtained. Further, the substitution elements Zn, Ga, Fe, Sn, and Mn may be substituted not only at the Cu site but also at the V site.
　［参考例２］
　参考例２では、ゾルゲル法を用いてα－Ｃｕ２Ｖ２Ｏ７の多結晶焼結体（セラミックス）試料を作製した。具体的には、Ｃｕ（ＮＯ３）２３Ｈ２Ｏを純水に溶かし、Ｖ２Ｏ５をクエン酸に溶かし、これら二つの溶液を混合して室温で２ｈ撹拌する。撹拌された混合液とポリエチレングリコール（重合度５０００００）とを、質量比９５：５の割合でビーカーに加え、ビーカーの周囲を８０℃の水に浸しながら溶かす（１．５ｈ）。そして、ポリエチレングリコールが全て溶けたらビーカーの周囲を氷水に浸して急冷しゲルを生成する。なお、Ｖ２Ｏ５に加えてまたは代わりにＶ２Ｏ３を用いてもよい。 [Reference Example 2]
In Reference Example 2, a polycrystalline sintered body (ceramics) sample of α-Cu 2 V 2 O 7 was prepared by using the sol-gel method. Specifically, Cu (NO 3 ) 2 3H 2 O is dissolved in pure water, V 2 O 5 is dissolved in citric acid, and these two solutions are mixed and stirred at room temperature for 2 hours. The stirred mixed liquid and polyethylene glycol (polymerization degree: 500,000) are added to a beaker at a mass ratio of 95: 5, and the periphery of the beaker is dissolved while being immersed in water at 80 ° C. (1.5 h). Then, when all of the polyethylene glycol is melted, the periphery of the beaker is immersed in ice water and rapidly cooled to form a gel. Note that V 2 O 3 may be used in addition to or instead of V 2 O 5 .
　その後、生成されたゲルを電気炉に入れ、３９３Ｋ（１２０℃）まで昇温後、その温度で３ｈ保持し乾燥させ、更に６７３Ｋ（４００℃）まで昇温後、その温度で５ｈ保持しクエン酸をとばし、粉末を得る。 Then, put the generated gel in an electric furnace, raise the temperature to 393K (120 ° C), hold at that temperature for 3h and dry, raise the temperature further to 673K (400 ° C), hold for 5h at that temperature, and add citric acid. And powder is obtained.
　次に、得られた粉末を電気炉から取り出し、メノウ乳鉢と乳棒で３０分程度混合した。混合した粉末をペレット状に成形し、アルミナ製のルツボに入れて８７３～９２３Ｋ（６００～６５０℃）で５ｈ焼結した。 Next, the obtained powder was taken out of the electric furnace and mixed with an agate mortar and pestle for about 30 minutes. The mixed powder was formed into pellets, placed in an alumina crucible, and sintered at 873 to 923K (600 to 650 ° C) for 5 hours.
　図６は、ゾルゲル法を用いて製造したα－Ｃｕ２Ｖ２Ｏ７の走査型電子顕微鏡（ＳＥＭ）写真を示す図である。図６に示すように、参考例２に係るα－Ｃｕ２Ｖ２Ｏ７は、大きさが２～３μｍ程度の結晶粒が凝集した負熱膨張材料である。 FIG. 6 is a view showing a scanning electron microscope (SEM) photograph of α-Cu 2 V 2 O 7 manufactured by using the sol-gel method. As shown in FIG. 6, α-Cu 2 V 2 O 7 according to Reference Example 2 is a negative thermal expansion material in which crystal grains having a size of about 2 to 3 μm are aggregated.
　［実施例２］
　実施例２では、参考例２と同様のゾルゲル法を用いてβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７の多結晶焼結体（セラミックス）試料を作製した。なお、参考例２と比較した場合、実施例２では、原料として亜鉛を含む化合物（例えばＺｎＯ）を用いている点が主な相違点である。したがって具体的な製造方法は、参考例１に記載の通りであり、具体的な説明は省略する。 [Example 2]
In Example 2, a β-Cu 1.8 Zn 0.2 V 2 O 7 polycrystalline sintered body (ceramics) sample was prepared by using the same sol-gel method as in Reference Example 2. In comparison with Reference Example 2, the main difference in Example 2 is that a compound containing zinc (for example, ZnO) is used as a raw material. Therefore, the specific manufacturing method is as described in Reference Example 1, and the specific description is omitted.
　図７は、ゾルゲル法を用いて製造したβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７の走査型電子顕微鏡（ＳＥＭ）写真を示す図である。図７に示すように、参考例２に係るα－Ｃｕ２Ｖ２Ｏ７は、大きさが２～３μｍ程度の結晶粒が凝集した負熱膨張材料である。 FIG. 7 is a view showing a scanning electron microscope (SEM) photograph of β-Cu 1.8 Zn 0.2 V 2 O 7 produced by using the sol-gel method. As shown in FIG. 7, α-Cu 2 V 2 O 7 according to Reference Example 2 is a negative thermal expansion material in which crystal grains having a size of about 2 to 3 μm are aggregated.
　ゾルゲル法を用いた製造方法は、水溶液にポリエチレングリコールを加えてゲルを生成する工程を含んでいる。これにより、スプレードライ法で製造するよりも微細な結晶粒の生成が可能となる。 The manufacturing method using the sol-gel method includes the step of adding a polyethylene glycol to an aqueous solution to generate a gel. This makes it possible to generate finer crystal grains than those produced by the spray dry method.
　［実施例３］
　実施例３では、スプレードライ法を用いてβ－Ｃｕ１．８Ｚｎ０．２Ｖ１．９Ｓｉ０．１Ｏ７の多結晶焼結体（セラミックス）試料を作製した。具体的には、化学量論比で秤量したＣｕＯ、ＺｎＯ、ＳｉＯ２及びＶ２Ｏ５（いずれも純度９９．９％）の粉末を乳鉢で混合し、温度９４３Ｋの大気中で１０時間焼成した。得られた粉末を、乳鉢ですりつぶし、クエン酸とともに純水に溶かす。その際、試料粉末１ｇに対して無水クエン酸３ｇ、純水約１００ｍｌを加え、試料粉末が全て溶けるまでマグネティックスターラーを用いて撹拌する。なお、Ｖ２Ｏ５に加えてまたは代わりにＶ２Ｏ３を用いてもよい。また、ＳｉＯ２に加えてまたは代わりに純度がほぼ１００％に近いＳｉを用いてもよい。なお、その後、実施例１と同様の方法で負熱膨張材料を製造した。 [Example 3]
In Example 3, a polycrystalline sintered body (ceramics) sample of β-Cu 1.8 Zn 0.2 V 1.9 Si 0.1 O 7 was prepared by using a spray dry method. Specifically, powders of CuO, ZnO, SiO 2 and V 2 O 5 (each having a purity of 99.9%) weighed in a stoichiometric ratio were mixed in a mortar and baked in the atmosphere at a temperature of 943K for 10 hours. .. The obtained powder is ground in a mortar and dissolved in pure water together with citric acid. At that time, 3 g of anhydrous citric acid and about 100 ml of pure water were added to 1 g of the sample powder, and the mixture was stirred with a magnetic stirrer until all the sample powder was dissolved. Note that V 2 O 3 may be used in addition to or instead of V 2 O 5 . Also, in addition to or instead of SiO 2 , Si having a purity close to 100% may be used. After that, a negative thermal expansion material was manufactured by the same method as in Example 1.
　［実施例４］
　実施例４では、スプレードライ法を用いてβ－Ｃｕ１．８Ｚｎ０．２Ｖ１．９Ｍｎ０．１Ｏ７の多結晶焼結体（セラミックス）試料を作製した。具体的には、化学量論比で秤量したＣｕＯ、ＺｎＯ、Ｍｎ２Ｏ３及びＶ２Ｏ５（いずれも純度９９．９％）の粉末を乳鉢で混合し、温度９４３Ｋの大気中で１０時間焼成した。得られた粉末を、乳鉢ですりつぶし、クエン酸とともに純水に溶かす。その際、試料粉末１ｇに対して無水クエン酸３ｇ、純水約１００ｍｌを加え、試料粉末が全て溶けるまでマグネティックスターラーを用いて撹拌する。なお、Ｖ２Ｏ５に加えてまたは代わりにＶ２Ｏ３を用いてもよい。また、Ｍｎ２Ｏ３に加えてまたは代わりに純度がほぼ１００％に近いＭｎやＭｎＯを用いてもよい。その後、実施例１と同様の方法で負熱膨張材料を製造した。 [Example 4]
In Example 4, a polycrystalline sintered body (ceramics) sample of β-Cu 1.8 Zn 0.2 V 1.9 Mn 0.1 O 7 was prepared by using the spray dry method. Specifically, powders of CuO, ZnO, Mn 2 O 3 and V 2 O 5 (each having a purity of 99.9%) weighed in a stoichiometric ratio are mixed in a mortar, and the mixture is mixed in the atmosphere at a temperature of 943K for 10 hours. Baked. The obtained powder is ground in a mortar and dissolved in pure water together with citric acid. At that time, 3 g of anhydrous citric acid and about 100 ml of pure water were added to 1 g of the sample powder, and the mixture was stirred with a magnetic stirrer until all the sample powder was dissolved. Note that V 2 O 3 may be used in addition to or instead of V 2 O 5 . Further, in addition to or instead of Mn 2 O 3 , Mn or MnO having a purity close to 100% may be used. Then, a negative thermal expansion material was manufactured in the same manner as in Example 1.
　（負熱膨張材料における結晶粒）
　次に、実施例に係る負熱膨張材料を構成する結晶粒の大きさについて説明する。なお、粒度分布の測定は、レーザー回折／散乱式粒径分布評価法によって行った。 (Crystal grains in negative thermal expansion material)
Next, the size of the crystal grains forming the negative thermal expansion material according to the example will be described. The particle size distribution was measured by a laser diffraction / scattering particle size distribution evaluation method.
　図８（ａ）は、実施例３に係る負熱膨張材料の粒径と体積頻度との関係を示す図、図８（ｂ）は、実施例４に係る負熱膨張材料の粒径と体積頻度との関係を示す図、図８（ｃ）は、実施例１に係る負熱膨張材料の粒径と体積頻度との関係を示す図である。図９は、実施例３、実施例４および実施例１に係る負熱膨張材料のＸ線回折パターンを示す図である。図９に示すように、実施例３および実施例４に係る負熱膨張材料は、実施例１に係る負熱膨張材料と同様に、単斜晶のβ相であることがわかる。 FIG. 8A is a diagram showing the relationship between the particle size and the volume frequency of the negative thermal expansion material according to Example 3, and FIG. 8B is the particle size and volume of the negative thermal expansion material according to Example 4. FIG. 8C is a diagram showing the relationship with the frequency, and FIG. 8C is a diagram showing the relationship between the particle size and the volume frequency of the negative thermal expansion material according to Example 1. FIG. 9 is a diagram showing X-ray diffraction patterns of the negative thermal expansion materials according to Example 3, Example 4, and Example 1. As shown in FIG. 9, it can be seen that the negative thermal expansion materials according to Example 3 and Example 4 are monoclinic β-phase, like the negative thermal expansion materials according to Example 1.
　また、図８（ａ）に示すように、実施例３に係るβ－Ｃｕ１．８Ｚｎ０．２Ｖ１．９Ｓｉ０．１Ｏ７は、体積頻度中心粒径が４．０μｍ程度の多数の結晶粒が凝集した負熱膨張材料である。また、図８（ｂ）に示すように、実施例４に係るβ－Ｃｕ１．８Ｚｎ０．２Ｖ１．９Ｍｎ０．１Ｏ７は、体積頻度中心粒径が４．１μｍ程度の多数の結晶粒が凝集した負熱膨張材料である。また、図８（ｃ）に示すように、実施例１に係るβ－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７は、体積頻度中心粒径が２．７μｍ程度の多数の結晶粒が凝集した負熱膨張材料である。 Further, as shown in FIG. 8A, β-Cu 1.8 Zn 0.2 V 1.9 Si 0.1 O 7 according to Example 3 has a volume frequency central particle diameter of about 4.0 μm. It is a negative thermal expansion material in which a large number of crystal grains are aggregated. Further, as shown in FIG. 8B, β-Cu 1.8 Zn 0.2 V 1.9 Mn 0.1 O 7 according to Example 4 has a volume frequency central particle diameter of about 4.1 μm. It is a negative thermal expansion material in which a large number of crystal grains are aggregated. In addition, as shown in FIG. 8C, in β-Cu 1.8 Zn 0.2 V 2 O 7 according to Example 1, a large number of crystal grains having a volume frequency center particle diameter of about 2.7 μm aggregated. It is a negative thermal expansion material.
　また、前述の製造方法は、ゲルを加熱し、有機酸を分解する工程と、ゲルの有機酸が分解されて生成された粉末を焼成して酸化物焼成体を生成する工程と、を含んでいる。これにより、比較的低エネルギーで所望の形状の酸化物焼結体を生成できる。 Further, the above-described manufacturing method includes a step of heating the gel to decompose the organic acid, and a step of firing the powder generated by decomposing the organic acid of the gel to produce an oxide fired body. There is. As a result, an oxide sintered body having a desired shape can be produced with relatively low energy.
　なお、各実施例で用いられる有機酸は、クエン酸以外に酢酸であってもよい。また、水溶液として化合物の原料が分散しやすい有機酸であれば、硝酸などの他の物質であってもよい。 Note that the organic acid used in each example may be acetic acid instead of citric acid. Further, other substances such as nitric acid may be used as long as they are organic acids in which the raw material of the compound is easily dispersed as an aqueous solution.
　次に、前述の各ＳＥＭ写真に写っている結晶粒の構造について更に詳述する。図１０（ａ）は、ＳＥＭ写真における結晶粒を模式的に示した図、図１０（ｂ）は、結晶粒の内部構造を示す図、図１０（ｃ）は、負熱膨張の発現メカニズムを説明するための図である。 Next, the structure of the crystal grains shown in the above SEM photographs will be described in more detail. 10A is a diagram schematically showing crystal grains in an SEM photograph, FIG. 10B is a diagram showing internal structures of crystal grains, and FIG. 10C is a mechanism of negative thermal expansion. It is a figure for explaining.
　図１０（ａ）に示すように、酸化物多結晶焼結体は、径が数μｍから数十μｍの複数の粒塊が重なり合い固まったものである。また、図１０（ｂ）に示すように、粒塊は、複数の結晶粒ＣＧが凝集したものであり、各結晶粒ＣＧの間に空隙ＡＳが形成されている。 As shown in FIG. 10 (a), the oxide polycrystalline sintered body is formed by stacking a plurality of agglomerates having a diameter of several μm to several tens of μm. Further, as shown in FIG. 10B, the agglomerate is an aggregate of a plurality of crystal grains CG, and voids AS are formed between the crystal grains CG.
　また、図１０（ｃ）に示すように、結晶の負熱膨張は必ずしも等方的に大きさが変化するわけではない。例えば、β－Ｃｕ１．８Ｚｎ０．２Ｖ２Ｏ７の場合、低温ＴＬから高温ＴＨ（＞ＴＬ）に温度が上昇すると、結晶の単位格子のａ軸とｃ軸の方向に縮むが、ｂ軸の方向に延びる。そのため、仮にｂ軸の方向に空隙がある場合、空隙で結晶のｂ軸方向の延びが吸収されるため、焼結体全体としては負熱膨張が大きくなると考えられる。 Further, as shown in FIG. 10C, the negative thermal expansion of the crystal does not necessarily change isotropically in magnitude. For example, in the case of β-Cu 1.8 Zn 0.2 V 2 O 7 , when the temperature rises from low temperature TL to high temperature TH (> TL), it shrinks in the a-axis and c-axis directions of the unit cell of the crystal, It extends in the direction of the b-axis. Therefore, if there is a void in the b-axis direction, it is considered that the void absorbs the extension of the crystal in the b-axis direction, so that the negative thermal expansion of the sintered body as a whole becomes large.
　上述のように、本開示の実施の形態に係る製造方法で製造された負熱膨張材料は、１００～５００Ｋ程度までの広い温度範囲で、温度変化に対して線膨張係数がほぼ一定であり、材料機能設計が容易である。また、主にＣｕ、Ｚｎ、Ｖといった安価な元素で構成されていること、酸化物で合成温度も低く、製造が容易であること、微粒子が得られること、などの工業的メリットがある。また、本実施の形態に係るスプレードライ法やゾルゲル法といった製造方法は、粉砕法と異なるものであり、負熱膨張を発現する組織を壊すことなく所望の形態の負熱膨張材料を製造できる新たな方法である。 As described above, the negative thermal expansion material manufactured by the manufacturing method according to the embodiment of the present disclosure has a substantially constant linear expansion coefficient with respect to temperature change in a wide temperature range of about 100 to 500K, Material functional design is easy. Further, there are industrial merits such as being mainly composed of inexpensive elements such as Cu, Zn, and V, being an oxide, having a low synthesis temperature, being easy to manufacture, and being able to obtain fine particles. Further, a manufacturing method such as a spray dry method or a sol-gel method according to the present embodiment is different from the pulverization method, and a new negative thermal expansion material having a desired shape can be manufactured without destroying a tissue expressing negative thermal expansion. That's the method.
　以上、本開示を実施の形態をもとに説明した。この実施の形態は例示であり、それらの各構成要素や各処理プロセスの組合せにいろいろな変形例が可能なこと、またそうした変形例も本開示の範囲にあることは当業者に理解されるところである。 Above, the present disclosure has been described based on the embodiments. This embodiment is merely an example, and it will be understood by those skilled in the art that various modifications can be made to the combinations of their respective constituent elements and processing processes, and that such modifications are also within the scope of the present disclosure. is there.
　本開示の一般式（１）Ｃｕ２－ｘＲｘＶ２Ｏ７（ＲはＺｎ、Ｇａ、Ｆｅ、Ｓｎ、Ｍｎから選ばれる少なくとも１種の元素、０≦ｘ＜２）で表される酸化物焼結体、および、一般式（２）Ｃｕ２－ｘＲｘＶ２－ｙＭｙＯ７（ＲはＺｎ、Ｇａ、Ｆｅ、Ｓｎ、Ｍｎから選ばれる少なくとも１種の元素、ＭはＭｇ、Ｓｉ、Ａｌ、Ｔｉ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｓｎから選ばれる少なくとも１種の元素、０≦ｘ＜２、０＜ｙ＜２）で表される酸化物焼結体は、通常材料が示す熱膨張を相殺して抑制する熱膨張抑制剤として利用することができる。更に、特定の温度範囲においては、正にも負にも膨張しない、ゼロ熱膨張材料をも作製できる。 Oxidation represented by the general formula (1) Cu 2-x R x V 2 O 7 (R is at least one element selected from Zn, Ga, Fe, Sn, and Mn, 0 ≦ x <2) of the present disclosure things sintered body, and at least one element general formula (2) Cu 2-x R x V 2-y M y O 7 (R is Zn, Ga, Fe, Sn, selected from Mn, M is Mg , Si, Al, Ti, Cr, Mn, Fe, Co, Ni, Sn, an oxide sintered body represented by 0 ≦ x <2, 0 <y <2), It can be used as a thermal expansion inhibitor that offsets and suppresses the thermal expansion of ordinary materials. In addition, zero thermal expansion materials can be made that do not expand positively or negatively in a particular temperature range.
　具体的には、温度による形状や寸法の変化を嫌う精密光学部品や機械部品、プロセス機器・工具、ファイバーグレーティングの温度補償材、プリント回路基板、電子部品の封止材、熱スイッチ、冷凍機部品、人工衛星部品などに利用することができる。特に、正の熱膨張率の大きな樹脂のマトリックス相に負熱膨張材料が分散された複合材料とすることで、樹脂材料においても熱膨張を抑制、制御することが可能となるため、様々な用途での利用が可能となる。また、粒径が小さいことにより、マイクロメートルレベルの局所領域の熱膨張制御も可能となり、例えば、電子デバイス内部の熱膨張制御にも利用できる。このように、粒径が小さな負熱膨張材料は、広範な産業利用が可能となる。 Specifically, precision optical parts and mechanical parts that do not want to change shape and dimensions due to temperature, process equipment and tools, temperature compensating materials for fiber gratings, printed circuit boards, sealing materials for electronic parts, thermal switches, refrigerator parts. It can be used for artificial satellite parts. In particular, by using a composite material in which a negative thermal expansion material is dispersed in a matrix phase of a resin having a large positive coefficient of thermal expansion, it is possible to suppress and control the thermal expansion of the resin material as well, so that various applications can be achieved. Can be used in. Moreover, since the particle size is small, it is possible to control the thermal expansion of the local region of the micrometer level, and for example, it can be used for the thermal expansion control inside the electronic device. As described above, the negative thermal expansion material having a small particle size can be widely used in industry.

Claims (12)

  1. 　一般式（１）Ｃｕ２－ｘＲｘＶ２Ｏ７（ＲはＺｎ、Ｇａ、Ｆｅ、Ｓｎ、Ｍｎから選ばれる少なくとも１種の元素、０≦ｘ＜２）で表される化合物の原料と有機酸とを含む水溶液を準備する工程を含む負熱膨張材料の製造方法。 A raw material of a compound represented by the general formula (1) Cu 2−x R x V 2 O 7 (R is at least one element selected from Zn, Ga, Fe, Sn and Mn, 0 ≦ x <2) A method for producing a negative thermal expansion material, comprising the step of preparing an aqueous solution containing an organic acid.
  2. 　一般式（２）Ｃｕ２－ｘＲｘＶ２－ｙＭｙＯ７（ＲはＺｎ、Ｇａ、Ｆｅ、Ｓｎ、Ｍｎから選ばれる少なくとも１種の元素、ＭはＭｇ、Ｓｉ、Ａｌ、Ｔｉ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｓｎから選ばれる少なくとも１種の元素、０≦ｘ＜２、０＜ｙ＜２）で表される化合物の原料と有機酸とを含む水溶液を準備する工程を含む負熱膨張材料の製造方法。 At least one element general formula (2) Cu 2-x R x V 2-y M y O 7 (R is Zn, Ga, Fe, Sn, selected from Mn, M is Mg, Si, Al, Ti, Step of preparing an aqueous solution containing at least one element selected from Cr, Mn, Fe, Co, Ni and Sn, a raw material of a compound represented by 0 ≦ x <2, 0 <y <2) and an organic acid A method for producing a negative thermal expansion material containing:
  3. 　前記水溶液を用いてスプレードライ法により造粒し、有機酸塩の粉末を生成する工程を含むことを特徴とする請求項１または２に記載の負熱膨張材料の製造方法。 The method for producing a negative thermal expansion material according to claim 1 or 2, comprising a step of granulating the organic acid salt by a spray dry method using the aqueous solution to generate a powder of an organic acid salt.
  4. 　前記水溶液を用いてフリーズドライ法により造粒し、有機酸塩の粉末を生成する工程を含むことを特徴とする請求項１または２に記載の負熱膨張材料の製造方法。 The method for producing a negative thermal expansion material according to claim 1 or 2, which further comprises a step of granulating the organic acid salt using the aqueous solution by a freeze-dry method to produce a powder of an organic acid salt.
  5. 　前記有機酸塩の粉末を加熱し、有機酸を分解する工程と、
    　有機酸が分解された前記粉末を焼成して酸化物焼結体を生成する工程と、
    　を含むことを特徴とする請求項３または４に記載の負熱膨張材料の製造方法。     Heating the powder of the organic acid salt to decompose the organic acid,
    A step of firing the powder in which the organic acid is decomposed to produce an oxide sintered body,
    The method for producing a negative thermal expansion material according to claim 3 or 4, further comprising:
  6. 　前記水溶液にポリエチレングリコールを加えてゲルを生成する工程を含む請求項１乃至５のいずれか１項に記載の負熱膨張材料の製造方法。 The method for producing a negative thermal expansion material according to any one of claims 1 to 5, comprising a step of adding a polyethylene glycol to the aqueous solution to generate a gel.
  7. 　前記ゲルを加熱し、有機酸を分解する工程と、
    　前記ゲルの有機酸が分解されて生成された粉末を焼成して酸化物焼成体を生成する工程と、
    　を含むことを特徴とする請求項６に記載の負熱膨張材料の製造方法。     Heating the gel to decompose organic acids,
    A step of firing a powder produced by decomposing the organic acid of the gel to produce an oxide fired body,
    The method for manufacturing a negative thermal expansion material according to claim 6, further comprising:
  8. 　前記有機酸は、クエン酸、酢酸又は硝酸であることを特徴とする請求項１乃至７のいずれか１項に記載の負熱膨張材料の製造方法。 The method for producing a negative thermal expansion material according to any one of claims 1 to 7, wherein the organic acid is citric acid, acetic acid or nitric acid.
  9. 　前記ＲはＺｎであることを特徴とする請求項１乃至８のいずれか１項に記載の負熱膨張材料の製造方法。 The method for producing a negative thermal expansion material according to any one of claims 1 to 8, wherein R is Zn.
  10. 　前記一般式（１）におけるｘは、０．１５～１であることを特徴とする請求項９に記載の負熱膨張材料の製造方法。 The method for producing a negative thermal expansion material according to claim 9, wherein x in the general formula (1) is 0.15 to 1.
  11. 　前記ＭはＳｉまたはＭｎであることを特徴とする請求項２に記載の負熱膨張材料の製造方法。 The method for producing a negative thermal expansion material according to claim 2, wherein the M is Si or Mn.
  12. 　前記一般式（２）におけるｙは、０．０５～０．５であることを特徴とする請求項１１に記載の負熱膨張材料の製造方法。 The method for producing a negative thermal expansion material according to claim 11, wherein y in the general formula (2) is 0.05 to 0.5.
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JP2021062995A (en) * 2019-10-16 2021-04-22 日本化学工業株式会社 Method for producing vanadium compound
WO2022114004A1 (en) * 2020-11-30 2022-06-02 国立大学法人東海国立大学機構 Negative thermal expansion material, composite material, method for manufacturing negative thermal expansion material, and component
WO2023181781A1 (en) * 2022-03-23 2023-09-28 日本化学工業株式会社 Negative thermal expansion material, method for manufacturing same, and composite material
JP7410249B2 (en) 2022-03-23 2024-01-09 日本化学工業株式会社 Negative thermal expansion material, its manufacturing method and composite material

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