CN113257507B - Rare earth RECrWO for low-temperature magnetic refrigeration 6 Oxide material and preparation method - Google Patents

Rare earth RECrWO for low-temperature magnetic refrigeration 6 Oxide material and preparation method Download PDF

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CN113257507B
CN113257507B CN202110532927.XA CN202110532927A CN113257507B CN 113257507 B CN113257507 B CN 113257507B CN 202110532927 A CN202110532927 A CN 202110532927A CN 113257507 B CN113257507 B CN 113257507B
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CN113257507A (en
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张义坤
田耘
张彬
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University of Shanghai for Science and Technology
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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
    • H01F1/012—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials adapted for magnetic entropy change by magnetocaloric effect, e.g. used as magnetic refrigerating material
    • H01F1/017—Compounds
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G41/00—Compounds of tungsten
    • C01G41/006—Compounds containing, besides tungsten, two or more other elements, with the exception of oxygen or hydrogen
    • 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
    • H01F1/012—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials adapted for magnetic entropy change by magnetocaloric effect, e.g. used as magnetic refrigerating material
    • H01F1/015—Metals or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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    • C01P2006/42—Magnetic properties
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    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
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Abstract

RECrWO applied to low-temperature magnetic refrigeration 6 The oxide material has an orthogonal easy-to-dissolve stone structure and belongs to a polar space group Pna2 1 。RECrWO 6 The isothermal magnetic entropy of the oxide material under the change of an external field of 0-5T is changed into 3.2-5.8J/kgK; under the change of an external field of 0 to 7T, the isothermal magnetic entropy is changed into 4.9 to 9.5J/kgK. The preparation method comprises the following steps: completely dissolving tungsten chloride into an alcohol solution, adding salt containing rare earth elements and chromium salt according to the molar ratio of metal ions, and fully mixing; adding citric acid into the mixed solution, heating and stirring to form sol; heating, drying and evaporating the sol to dryness to obtain gel; then calcining the gel in a muffle furnace to obtain a sinter; and tabletting and molding the sintered substance, and sintering and cooling in a muffle furnace to obtain a finished product. RECrWO prepared by the method of the invention 6 The oxide material is applied to the field of low-temperature magnetic refrigeration, the price of the selected raw material is low, the used process is simple, the requirement on equipment is low, and the oxide material is suitable for industrial production.

Description

Rare earth RECrWO for low-temperature magnetic refrigeration 6 Oxide material and preparation method
Technical Field
The invention belongs to the technical field of rare earth magnetic functional materials, and particularly relates to a rare earth RECrWO applied to low-temperature magnetic refrigeration 6 Oxide material and a preparation method.
Background
The magnetic refrigeration material is a novel magnetic functional material, mainly utilizes the magnetic thermal effect or magnetic card effect of the magnetic material to realize the refrigeration function, and is a pollution-free refrigeration working medium material. The principle of magnetic refrigeration is that an external magnetic field is utilized to switch the ordered magnetic moment and the disordered magnetic moment in a magnetic working medium, so that phase change is realized, and the heat absorption and the heat release of a magnet are caused by the entropy change in the material, so that the aim of refrigeration is fulfilled. When the magnetic refrigeration material enters a high magnetic field area and is subjected to isothermal magnetization, the temperature rises and releases heat to the outside, and when the magnetic refrigeration material enters a zero magnetic field or low magnetic field area and is subjected to adiabatic demagnetization, the temperature is reduced and absorbs heat from the outside, so that refrigeration cycle is realized. Compared with the traditional refrigeration technology, the magnetic refrigeration method not only gets rid of the dependence on a series of harmful greenhouse gases such as Freon and the like, but also can save 20-30% of the energy consumption compared with the traditional mainstream refrigeration system, and has the advantages of low noise, good reliability, small volume, easy maintenance, long service life and the like.
The main problem to be solved for realizing the wide application of the magnetic refrigeration technology is the selection of the magnetic working medium. Elementary gadolinium is found to have a huge magnetocaloric effect in an indoor temperature region in many studies, but the phase transition temperature is single and expensive. Thereafter, studies have been made on heavy rare earth alloys, rare earth-transition intermetallic compounds, transition metals and alloys thereof, etc., such as Gd-Si-Ge series, la-Fe-Si series, ni-Mn based, mnAs based, etc. Besides the cost problem, the refrigeration capacity of the material is more important, and some materials have hysteresis phenomena although the magnetic entropy change is larger, so that the refrigeration cycle is influenced. At present, the low-temperature magnetic refrigeration material is mainly a rare earth intermetallic compound material, and the materials have the defects of high raw material price, complex preparation process and the like.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a rare earth RECrWO applied to low-temperature magnetic refrigeration 6 The rare earth oxide has no hysteresis and thermal hysteresis, and has the advantages of low cost and simple preparation, the RECrWO of the invention 6 The oxide material is applied to the field of low-temperature-region magnetic refrigeration, the selected raw materials are low in price, the used process is simple, the requirement on equipment is low, and the oxide material is suitable for industrial production.
In order to achieve the purpose, the invention adopts the following technical scheme:
rare earth RECrWO applied to low-temperature magnetic refrigeration 6 An oxide material characterized by: it has an orthogonal easy-to-dissolve stone structure with orderly arranged metal ions, and belongs to a polar space group Pna2 1 (ii) a Wherein RE is at least one element of Gd, dy, ho or Er in the rare earth elements.
Preferably, the invention is applied to the rare earth RECrWO of low-temperature magnetic refrigeration 6 Under the change of an external field of 0-5T, the isothermal magnetic entropy of the oxide material is changed into 3.2-5.8J/kgK; under the change of an external field of 0 to 7T, the isothermal magnetic entropy is changed into 4.9 to 9.5J/kgK.
Preference is given toIn addition, the invention is applied to the rare earth RECrWO of the low-temperature magnetic refrigeration 6 An oxide material, wherein the molar stoichiometric ratio of RE, cr, W and O is 1.
The invention is applied to RECrWO of low-temperature magnetic refrigeration 6 A method of preparing an oxide material comprising the steps of:
step 1: adding tungsten chloride into an alcohol solution with the volume concentration of 80-95%, stirring until the tungsten chloride is fully dissolved, and then adding a salt containing rare earth elements and a chromium salt into the tungsten chloride solution according to the molar mass ratio of metal ions of 1;
and 2, step: adding citric acid into the mixed salt solution obtained in the step 1, wherein the molar ratio of the citric acid to tungsten chloride is 1: 2.8-1: 3.2, heating to 50-70 ℃, keeping the temperature, and continuously stirring until the solution is evaporated to 35-50% of the volume total amount of the original solution to obtain sol;
and step 3: putting the sol obtained after stirring in the step 2 into a drying oven, and keeping the sol at the temperature of 80-90 ℃ for 0.5-1 h to obtain gel;
and 4, step 4: after the gel obtained in the step 3 is cooled, calcining the gel in a muffle furnace at the temperature of 500-600 ℃ for 5-6 h to obtain sinter powder;
and 5: tabletting and molding the sinter obtained in the step 4, sintering the powder in a muffle furnace at the temperature of 1100-1200 ℃ for 20-30 h, and cooling along with the furnace to obtain rare earth RECrWO 6 And (5) obtaining the finished product of the oxide material.
Preferably, in the step 1, rare earth nitrate or rare earth chloride is used as the rare earth element-containing salt.
Preferably, in the step 1, chromium salt is chromium nitrate or chromium chloride.
Preferably, in the step 1, the alcohol solution is used in a concentration of 90 to 95% by volume.
Preferably, in the step 2, citric acid with a molar ratio of 1.
Preferably, in the step 5, the powder is tabletted and molded by using a tablet machine; the crucible used is a corundum crucible.
Compared with the prior art, the invention has the following obvious substantive characteristics and remarkable advantages:
1. rare earth RECrWO of the invention 6 The oxide material is prepared by a sol-gel method, the cost of the used raw materials is low, the preparation method is simple, the requirement on equipment is low, and the method is suitable for industrial production;
2. the material has larger magnetic entropy change near the respective magnetic phase transition temperature, wider working temperature zone and good magnetic and thermal reversibility.
Detailed Description
The present invention is further analyzed by the following specific examples, which are not intended to limit the present invention in any way.
Example 1
Rare earth GdCrWO applied to low-temperature magnetic refrigeration 6 An oxide material having an orthogonal solvolite structure with an ordered arrangement of metal ions, belonging to the polar space group Pna2 1 。
GdCrWO applied to low-temperature magnetic refrigeration in the embodiment 6 A method of preparing an oxide material comprising the steps of:
step 1: adding 0.01mol of tungsten chloride into 50mL of 90% alcohol solution by volume concentration, stirring until the tungsten chloride is fully dissolved, and then adding 0.01mol of gadolinium nitrate and 0.01mol of chromium nitrate into the tungsten chloride solution to obtain a mixed salt solution;
step 2: adding 0.03mol of citric acid into the mixed salt solution obtained in the step 1, heating to 60 ℃, preserving heat, and continuously stirring until the volume of the solution evaporation solution is 20mL to obtain sol;
and step 3: putting the sol obtained after stirring in the step 2 into a drying oven, and keeping the sol for 1h at 90 ℃ to obtain gel;
and 4, step 4: after the gel obtained in the step 3 is cooled, calcining the gel in a muffle furnace at the temperature of 500 ℃ for 5 hours to obtain sinter powder;
and 5: tabletting and molding the sinter obtained in the step 4, sintering the powder in a muffle furnace at the temperature of 1200 ℃ for 24 hours, and cooling along with the furnace to obtain the rare earth GdCrWO 6 And (5) obtaining the finished product of the oxide material.
The finished product GdCrWO obtained in this example 6 Under the magnetic field change of 0-5T, the isothermal magnetic entropy becomes 5.7J/kgK; under the change of a magnetic field of 0-7T, the isothermal magnetic entropy is changed into 9.1J/kgK, and the isothermal magnetic entropy can be applied to low-temperature magnetic refrigeration. The material of the embodiment has larger magnetic entropy change near the respective magnetic phase transition temperature, has a wider working temperature zone, and also has good magnetic and thermal reversible properties.
Example 2
Rare earth ErCrWO applied to low-temperature magnetic refrigeration 6 An oxide material having an orthorhombic solvolite structure with an ordered arrangement of metal ions, belonging to the polar space group Pna2 1 。
ErCrWO applied to low-temperature magnetic refrigeration in the embodiment 6 A method of preparing an oxide material comprising the steps of:
step 1: adding 0.01mol of tungsten chloride into 50mL of 90% alcohol solution by volume concentration, stirring until the tungsten chloride is fully dissolved, and then adding 0.01mol of erbium nitrate and 0.01mol of chromium nitrate into the tungsten chloride solution to obtain a mixed salt solution;
step 2: adding 0.03mol of citric acid into the mixed salt solution obtained in the step 1, heating to 60 ℃, preserving heat, and continuously stirring until the volume of the solution evaporation solution is 20mL to obtain sol;
and step 3: putting the sol obtained after stirring in the step 2 into a drying oven, and keeping the sol at 90 ℃ for 1h to obtain gel;
and 4, step 4: after the gel obtained in the step 3 is cooled, calcining the gel in a muffle furnace at the temperature of 500 ℃ for 5 hours to obtain sinter powder;
and 5: tabletting and molding the sinter obtained in the step 4, sintering the powder in a muffle furnace at the temperature of 1100 ℃ for 24h, and cooling along with the furnace to obtain the rare earth ErCrWO 6 And (5) obtaining the finished product of the oxide material.
The finished product ErCrWO obtained in this example 6 Under the magnetic field change of 0-5T, the isothermal magnetic entropy becomes 3.5J/kgK; under the change of a magnetic field of 0-7T, the isothermal magnetic entropy is changed into 5.3J/kgK, and the isothermal magnetic entropy can be applied to low-temperature magnetic refrigeration. The material of the embodiment has larger magnetic entropy change near the respective magnetic phase transition temperature, has a wider working temperature zone, and also has good magnetic and thermal reversible properties.
Example 3
Rare earth Gd applied to low-temperature magnetic refrigeration 0.4 Er 0.6 CrWO 6 An oxide material having an orthorhombic solvolite structure with an ordered arrangement of metal ions, belonging to the polar space group Pna2 1 。
Gd applied to low-temperature magnetic refrigeration in the embodiment 0.4 Er 0.6 CrWO 6 A method of preparing an oxide material comprising the steps of:
step 1: adding 0.01mol of tungsten chloride into 50mL of 90% alcohol solution by volume concentration, stirring until the tungsten chloride is fully dissolved, and then adding 0.004mol of gadolinium nitrate, 0.006mol of erbium nitrate and 0.01mol of chromium nitrate into the tungsten chloride solution to obtain a mixed salt solution;
step 2: adding 0.03mol of citric acid into the mixed salt solution obtained in the step 1, heating to 60 ℃, preserving heat, and continuously stirring until the volume of the solution evaporation solution is 20mL to obtain sol;
and step 3: putting the sol obtained after stirring in the step 2 into a drying oven, and keeping the sol for 1h at 90 ℃ to obtain gel;
and 4, step 4: after the gel obtained in the step 3 is cooled, calcining the gel in a muffle furnace at the temperature of 500 ℃ for 5 hours to obtain sinter powder;
and 5: tabletting and molding the sinter obtained in the step 4, sintering the powder in a muffle furnace at the temperature of 1150 ℃ for 24 hours, and cooling along with the furnace to obtain rare earth Gd 0.4 Er 0.6 CrWO 6 And (5) obtaining the finished product of the oxide material.
Gd product obtained in this example 0.4 Er 0.6 CrWO 6 Isothermal magnetization under the magnetic field change of 0-5TThe entropy became 4.5J/kgK; under the change of a magnetic field of 0-7T, the isothermal magnetic entropy is changed into 6.9J/kgK, and the isothermal magnetic entropy can be applied to low-temperature magnetic refrigeration. The material of the embodiment has larger magnetic entropy change near the respective magnetic phase transition temperature, wider working temperature zone and good magnetic and thermal reversibility.
Example 4
Rare earth Gd applied to low-temperature magnetic refrigeration 0.3 Dy 0.3 Er 0.4 CrWO 6 An oxide material having an orthogonal solvolite structure with an ordered arrangement of metal ions, belonging to the polar space group Pna2 1 。
Gd applied to low-temperature magnetic refrigeration in the embodiment 0.3 Dy 0.3 Er 0.4 CrWO 6 A method of preparing an oxide material comprising the steps of:
step 1: adding 0.01mol of tungsten chloride into 50mL of 90% alcohol solution by volume concentration, stirring until the tungsten chloride is fully dissolved, and then adding 0.003mol of gadolinium nitrate, 0.003mol of dysprosium nitrate, 0.004mol of erbium nitrate and 0.01mol of chromium nitrate into the tungsten chloride solution to obtain a mixed salt solution;
and 2, step: adding 0.03mol of citric acid into the mixed salt solution obtained in the step 1, heating to 60 ℃, preserving heat, and continuously stirring until the volume of the solution evaporation solution is 20mL to obtain sol;
and 3, step 3: putting the sol obtained after stirring in the step 2 into a drying oven, and keeping the sol for 1h at 90 ℃ to obtain gel;
and 4, step 4: after the gel obtained in the step 3 is cooled, calcining the gel in a muffle furnace at the temperature of 500 ℃ for 5 hours to obtain sinter powder;
and 5: tabletting and molding the sinter obtained in the step 4, sintering the powder in a muffle furnace at the temperature of 1200 ℃ for 24 hours, and cooling along with the furnace to obtain rare earth Gd 0.3 Dy 0.3 Er 0.4 CrWO 6 And (5) obtaining the finished product of the oxide material.
Gd product obtained in this example 0.3 Dy 0.3 Er 0.4 CrWO 6 Isothermal magnetization under the magnetic field change of 0-5TThe entropy became 4.0J/kgK; under the change of a magnetic field of 0-7T, the isothermal magnetic entropy is changed into 6.1J/kgK, and the isothermal magnetic entropy can be applied to low-temperature magnetic refrigeration. The material of the embodiment has larger magnetic entropy change near the respective magnetic phase transition temperature, has a wider working temperature zone, and also has good magnetic and thermal reversible properties.
Example 5
Rare earth Dy applied to low-temperature magnetic refrigeration 0.4 Ho 0.2 Er 0.4 CrWO 6 An oxide material having an orthogonal solvolite structure with an ordered arrangement of metal ions, belonging to the polar space group Pna2 1 。
Dy applied to low-temperature magnetic refrigeration in embodiment 0.4 Ho 0.2 Er 0.4 CrWO 6 A method of preparing an oxide material comprising the steps of:
step 1: adding 0.01mol of tungsten chloride into 50mL of 90% alcohol solution by volume concentration, stirring until the tungsten chloride is fully dissolved, and then adding 0.004mol of dysprosium nitrate, 0.002mol of holmium nitrate, 0.004mol of erbium nitrate and 0.01mol of chromium nitrate into the tungsten chloride solution to obtain a mixed salt solution;
step 2: adding 0.03mol of citric acid into the mixed salt solution obtained in the step 1, heating to 60 ℃, preserving heat, and continuously stirring until the volume of the solution evaporation solution is 20mL to obtain sol;
and 3, step 3: putting the sol obtained after stirring in the step 2 into a drying oven, and keeping the sol at 90 ℃ for 1h to obtain gel;
and 4, step 4: after the gel obtained in the step 3 is cooled, calcining the gel in a muffle furnace at the temperature of 500 ℃ for 5 hours to obtain sinter powder;
and 5: tabletting and molding the sinter powder obtained in the step 4, sintering the powder in a muffle furnace at the temperature of 1200 ℃ for 24 hours, and cooling along with the furnace to obtain rare earth Dy 0.4 Ho 0.2 Er 0.4 CrWO 6 And (5) obtaining the finished product of the oxide material.
Dy finished product obtained in this example 0.4 Ho 0.2 Er 0.4 CrWO 6 Isothermal magnetization under the magnetic field change of 0-5TThe entropy became 3.7J/kgK; under the change of a magnetic field of 0-7T, the isothermal magnetic entropy is changed into 5.7J/kgK, and the isothermal magnetic entropy can be applied to low-temperature magnetic refrigeration. The material of the embodiment has larger magnetic entropy change near the respective magnetic phase transition temperature, has a wider working temperature zone, and also has good magnetic and thermal reversible properties.
Example 6
Rare earth Gd applied to low-temperature magnetic refrigeration 0.3 Dy 0.2 Ho 0.2 Er 0.3 CrWO 6 An oxide material having an orthorhombic solvolite structure with an ordered arrangement of metal ions, belonging to the polar space group Pna2 1 。
Gd applied to low-temperature magnetic refrigeration in embodiment 0.3 Dy 0.2 Ho 0.2 Er 0.3 CrWO 6 A method of preparing an oxide material comprising the steps of:
step 1: adding 0.01mol of tungsten chloride into 50mL of 90% alcohol solution by volume concentration, stirring until the tungsten chloride is fully dissolved, and then adding 0.003mol of gadolinium nitrate, 0.002mol of dysprosium nitrate, 0.002mol of holmium nitrate, 0.003mol of erbium nitrate and 0.01mol of chromium nitrate into the tungsten chloride solution to obtain a mixed salt solution;
step 2: adding 0.03mol of citric acid into the mixed salt solution obtained in the step 1, heating to 60 ℃, preserving heat, and continuously stirring until the volume of the solution evaporation solution is 20mL to obtain sol;
and 3, step 3: putting the sol obtained after stirring in the step 2 into a drying oven, and keeping the sol for 1h at 90 ℃ to obtain gel;
and 4, step 4: after the gel obtained in the step 3 is cooled, calcining the gel in a muffle furnace at the temperature of 500 ℃ for 5 hours to obtain sinter powder;
and 5: tabletting and molding the sinter obtained in the step 4, sintering the powder in a muffle furnace at the temperature of 1200 ℃ for 24 hours, and cooling along with the furnace to obtain rare earth Gd 0.3 Dy 0.2 Ho 0.2 Er 0.3 CrWO 6 And (5) obtaining the finished product of the oxide material.
Gd product obtained in this example 0.3 Dy 0.2 Ho 0.2 Er 0.3 CrWO 6 Under the change of a magnetic field of 0-5T, the isothermal magnetic entropy is changed into 3.9J/kgK; under the change of a magnetic field of 0-7T, the isothermal magnetic entropy is changed into 6.3J/kgK, and the isothermal magnetic entropy can be applied to low-temperature magnetic refrigeration. The material of the embodiment has larger magnetic entropy change near the respective magnetic phase transition temperature, has a wider working temperature zone, and also has good magnetic and thermal reversible properties.
Example 7
Rare earth DyCrWO applied to low-temperature magnetic refrigeration 6 An oxide material having an orthogonal solvolite structure with an ordered arrangement of metal ions, belonging to the polar space group Pna2 1 。
DyCrWO applied to low-temperature magnetic refrigeration in this embodiment 6 A method of preparing an oxide material comprising the steps of:
step 1: adding 0.01mol of tungsten chloride into 50mL of alcohol solution with volume concentration of 95%, stirring until the tungsten chloride is fully dissolved, and then adding 0.01mol of gadolinium nitrate and 0.01mol of chromium nitrate into the tungsten chloride solution to obtain a mixed salt solution;
step 2: adding 0.03mol of citric acid into the mixed salt solution obtained in the step 1, heating to 70 ℃, preserving heat, and continuously stirring until the volume of the solution evaporation solution is 20mL to obtain sol;
and step 3: putting the sol obtained after stirring in the step 2 into a drying oven, and keeping the sol at 80 ℃ for 0.5h to obtain gel;
and 4, step 4: after the gel obtained in the step 3 is cooled, calcining the gel in a muffle furnace at the temperature of 600 ℃ for 6 hours to obtain sinter powder;
and 5: tabletting and molding the sinter powder obtained in the step 4, sintering the powder in a muffle furnace at 1200 ℃ for 30h, and cooling along with the furnace to obtain rare earth DyCrWO 6 And (5) obtaining the finished product of the oxide material.
The finished product DyCrWO obtained in this example 6 Under the magnetic field change of 0-5T, the isothermal magnetic entropy becomes 3.7J/kgK; under the change of a magnetic field of 0-7T, the isothermal magnetic entropy is changed into 5.6J/kgK, and the isothermal magnetic entropy can be applied to low-temperature magnetic refrigeration. The materials of the present example are eachThe magnetic phase transition temperature is close to the magnetic entropy change, the working temperature zone is wide, and the magnetic and thermal reversible properties are good.
In summary, the above embodiments are applied to the RECrWO of low temperature magnetic refrigeration 6 An oxide material and its preparation method, the material has an orthogonal easy-to-dissolve stone structure, belonging to polar space group Pna2 1 。RECrWO 6 The isothermal magnetic entropy of the oxide material is changed to 3.2J/kgK to 5.8J/kgK under the change of an external field of 0 to 5T; under the change of an external field of 0-7T, the isothermal magnetic entropy is changed into 4.9J/kgK-9.5J/kgK. The preparation method comprises the following steps: firstly, completely dissolving tungsten chloride into an alcohol solution, then adding rare earth nitrate or rare earth chlorate and chromium nitrate or chromium chloride according to the molar ratio of metal ions, and fully mixing; then adding citric acid into the mixed solution, heating and stirring to form sol; heating, drying and evaporating the sol to dryness to obtain gel; then calcining the gel in a muffle furnace to obtain a sinter; and tabletting and forming the sinter, and sintering and cooling in a muffle furnace to obtain a finished product. RECrWO prepared in the above examples of the invention 6 The oxide material is applied to the field of low-temperature magnetic refrigeration, the price of the selected raw material is low, the used process is simple, the requirement on equipment is low, and the oxide material is suitable for industrial production.
While the embodiments of the present invention have been described, the present invention is not limited to the above embodiments, and various changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the present invention may be made in the form of equivalent substitutions without departing from the technical principle and inventive concept of the present invention.

Claims (7)

1. Rare earth RECrWO applied to low-temperature magnetic refrigeration 6 The preparation method of the oxide material is characterized by comprising the following steps: the oxide material has an orthogonal easy-to-dissolve stone structure with orderly arranged metal ions and belongs to a polar space group Pna2 1 (ii) a Wherein RE is at least one element of Gd, dy, ho or Er in the rare earth elements;
the preparation method specifically comprises the following steps:
step 1: adding tungsten chloride into an alcohol solution with the volume concentration of 80-95%, stirring until the tungsten chloride is fully dissolved, and then adding a salt containing rare earth elements and a chromium salt into the tungsten chloride solution according to the molar mass ratio of metal ions of 1;
step 2: adding citric acid with a molar ratio of 1 to tungsten chloride of 2.8-1 to 3.2 into the mixed salt solution obtained in the step 1, heating to 50-70 ℃, preserving heat, and continuously stirring until the solution is evaporated to 35-50% of the total volume of the original solution to obtain sol;
and 3, step 3: putting the sol obtained after stirring in the step 2 into a drying oven, and keeping the sol at the temperature of 80-90 ℃ for 0.5-1 h to obtain gel;
and 4, step 4: after the gel obtained in the step 3 is cooled, calcining the gel in a muffle furnace at the temperature of 500-600 ℃ for 5-6 h to obtain sinter powder;
and 5: tabletting and molding the sinter obtained in the step 4, sintering the powder in a muffle furnace at the temperature of 1100-1200 ℃ for 20-30 h, and cooling along with the furnace to obtain rare earth RECrWO 6 And (5) obtaining the finished product of the oxide material.
2. Rare earth RECrWO applied to low-temperature magnetic refrigeration according to claim 1 6 The preparation method of the oxide material is characterized by comprising the following steps: under the change of an external field of 0-5T, the isothermal magnetic entropy of the material is changed into 3.2-5.8J/kgK; under the change of an external field of 0 to 7T, the isothermal magnetic entropy is changed into 4.9 to 9.5J/kgK.
3. Rare earth RECrWO applied to low-temperature magnetic refrigeration according to claim 1 6 The preparation method of the oxide material is characterized by comprising the following steps: wherein the molar stoichiometric ratio of RE, cr, W and O is 1.
4. Rare earth RECrWO applied to low-temperature magnetic refrigeration according to claim 1 6 A method for producing an oxide material, characterized in that in the step 1The rare earth element-containing salt is rare earth nitrate or rare earth chloride.
5. Rare earth RECrWO applied to low-temperature magnetic refrigeration according to claim 1 6 The preparation method of the oxide material is characterized in that in the step 1, chromium nitrate or chromium chloride is adopted as the chromium salt.
6. Rare earth RECrWO applied to low-temperature magnetic refrigeration according to claim 1 6 The method for preparing the oxide material is characterized in that in the step 1, the volume concentration of the adopted alcohol solution is 90-95%.
7. Rare earth RECrWO applied to low-temperature magnetic refrigeration according to claim 1 6 The preparation method of the oxide material is characterized in that in the step 2, citric acid with a molar ratio of 1.
CN202110532927.XA 2021-05-17 2021-05-17 Rare earth RECrWO for low-temperature magnetic refrigeration 6 Oxide material and preparation method Active CN113257507B (en)

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