CN115274236A - Wide-temperature-zone large-magnetic-entropy lanthanum-iron-silicon-based room-temperature magnetic refrigeration material and preparation method thereof - Google Patents

Wide-temperature-zone large-magnetic-entropy lanthanum-iron-silicon-based room-temperature magnetic refrigeration material and preparation method thereof Download PDF

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CN115274236A
CN115274236A CN202210729804.XA CN202210729804A CN115274236A CN 115274236 A CN115274236 A CN 115274236A CN 202210729804 A CN202210729804 A CN 202210729804A CN 115274236 A CN115274236 A CN 115274236A
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赵文俞
鲜良
贺丹琪
张清杰
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Wuhan University of Technology WUT
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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
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    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • 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
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Abstract

The invention discloses a preparation method of a wide-temperature-zone large-magnetic-entropy lanthanum-iron-silicon-based room-temperature magnetic refrigeration material. The lanthanum-iron-silicon-based room-temperature magnetic refrigeration material is prepared by the high-energy ball milling-annealing method, the Curie temperature of the obtained lanthanum-iron-silicon-based room-temperature magnetic refrigeration material is in a room temperature region, the obtained lanthanum-iron-silicon-based room-temperature magnetic refrigeration material has a wider working temperature region and excellent magnetocaloric performance, and a new idea can be provided for the preparation of the high-performance lanthanum-iron-silicon-based room-temperature magnetic refrigeration material; and the related preparation process is simple, the cost is low, the requirement on reaction equipment is not high, and the preparation method is suitable for popularization and application.

Description

Wide-temperature-zone large-magnetic-entropy lanthanum-iron-silicon-based room-temperature magnetic refrigeration material and preparation method thereof
Technical Field
The invention belongs to the technical field of magnetic refrigeration materials, and particularly relates to a wide-temperature-zone large-magnetic-entropy lanthanum-iron-silicon-based room-temperature magnetic refrigeration material and a preparation method thereof.
Background
The traditional vapor compression refrigeration is the most mature refrigeration technology at present and is widely applied to refrigeration equipment such as refrigerators, air conditioners and the like, but the technology must use fluorine-containing refrigerant which has destructive effect on atmospheric environment; the problem to be solved urgently is to explore a novel refrigeration technology which is environment-friendly, efficient and energy-saving.
Magnetic refrigeration is a novel refrigeration technology which takes a magnetic material with a magnetocaloric effect as a refrigeration working medium, has the advantages of environmental protection, high efficiency, energy conservation, stability, reliability and the like, and is a technology which has the potential to replace the traditional compressor refrigeration. The second-level phase change material Gd is widely concerned due to the large magnetic entropy of the second-level phase change material Gd under a low field, and the Curie point of the second-level phase change material Gd is in a room temperature area and a wide working temperature area. However, gd is expensive and very easily oxidized, so that the Gd is difficult to be commercially applied. It is necessary to find materials with magnetocaloric properties comparable to Gd in other material systems, such as MnFe (P)1-xAsx)、Gd5(SixGe1-x)4Heusler alloy and La (Fe, si)13Alloys, and the like. Wherein, la (Fe, si)13The alloy system is considered to be the most promising material for replacing Gd and being applied to the room temperature magnetic refrigeration technology due to the excellent magnetocaloric effect, the non-toxicity, the environmental protection and the low price of the constituent elements, but the ferromagnetic-paramagnetic phase transition can be completed within a narrow temperature range, so that the magnetic refrigeration working temperature region is very narrow, and the further application is limited. Therefore, a method for making La (Fe, si)13The alloy has wide magnetic refrigeration working temperature zone, high magnetic entropy change and low driving magnetic field.
Due to functional phase La (Fe, si)13Phase of NaZn13The structure is complex, the factors influencing the peritectic reaction in the phase forming process are more, and the conventional preparation method (such as arc melting, vacuum induction melting and the like) needs to be realized by high-temperature annealing for one month in order to obtain more functional phases. The high-energy ball milling method can greatly shorten the annealing time, reduce the energy consumption and ensure the uniformity and the stability of the components and the performance of the product after the annealing treatment. However, the high ball-to-material ratio and high rotation speed in the conventional method easily cause the material to form cold welding, and can not really widen La (Fe, si)13The purpose of the alloy working temperature zone is achieved. Therefore, the method for further exploring the preparation method of the lanthanum-iron-silicon-based room temperature refrigeration material which has simple preparation process, low requirement on production equipment and the advantages of batch preparation, wide magnetic refrigeration working temperature zone and the like has important research and applicationMeaning.
Disclosure of Invention
The invention mainly aims to provide a preparation method of a wide-temperature-zone large-magnetic-entropy lanthanum-iron-silicon-based room-temperature magnetic refrigeration material aiming at the defects in the prior art, the method has the advantages of simple equipment requirement, low cost and low technical requirement on operators, and can lay a good foundation for large-scale preparation and large-scale application of high-performance lanthanum-iron-silicon-based materials.
In order to achieve the purpose, the invention adopts the technical scheme that:
a preparation method of a wide-temperature-area large-magnetic-entropy lanthanum-iron-silicon-based room-temperature magnetic refrigeration material comprises the steps of taking La, fe, co and Si powder as raw materials, carrying out high-energy ball milling on the raw materials under a protective atmosphere, and then carrying out pressing and annealing heat treatment to prepare the wide-temperature-area large-magnetic-entropy lanthanum-iron-silicon-based room-temperature magnetic refrigeration material.
In the scheme, la of the lanthanum-iron-silicon-based room-temperature refrigerating material1+zFe13-x-yCoxSiyWherein x is more than or equal to 0.88 and less than or equal to 1.06, y is more than or equal to 0.8 and less than or equal to 1.4, and z is more than or equal to 0 and less than or equal to 0.8..
Preferably, 0.94. Ltoreq. X.ltoreq.1.02.
Preferably, 1.0. Ltoreq. Y.ltoreq.1.2.
Preferably, 0.2. Ltoreq. Z.ltoreq.0.4.
In the above scheme, the batch preparation method is performed under a protective atmosphere, and specifically comprises the following steps:
1) Taking La powder, fe powder, co powder and Si powder as raw materials, and weighing the raw materials according to the stoichiometric ratio of the lanthanum-iron-silicon-based magnetic refrigeration material;
2) Performing high-energy ball milling on the weighed raw materials to prepare intermetallic compound powder;
3) Tabletting and molding the intermetallic compound powder obtained in the step 2), wherein the pressure is 10-50 MPa, and the pressure maintaining time is 3-10 min;
4) And (3) packaging the sample obtained in the step 3) in a quartz tube, and carrying out annealing heat treatment and quenching to obtain the lanthanum-iron-silicon-based magnetic refrigeration material.
In the scheme, the La powder, the Fe powder, the Co powder and the Si powder are all ground into high-purity powder, and the purity is over 99.5 wt.%.
In the above scheme, the anaerobic condition is a vacuum condition or an inert gas protection condition.
In the above scheme, the vacuum degree adopted by the vacuum condition is 1 × 10-4Pa or less; the inert gas can be N2Or Ar gas, etc.
Further, the purity of the inert gas is 99.9% or more.
In the scheme, the material of the grinding ball adopted in the high-energy ball milling step is zirconia, tungsten carbide or stainless steel; the ball-material ratio is (20-40): 1.
Preferably, the molded sample obtained in step 3) is further hermetically wrapped with a tantalum foil or a molybdenum foil so as not to be in direct contact with the quartz tube.
Preferably, in the step 4), a layer of refractory cotton is laid at the bottom of the quartz tube, so that the condition that the atmosphere in the tube is affected by the damage of the quartz tube during high-temperature service due to the reaction of La and the quartz tube is effectively prevented.
In the above scheme, the annealing heat treatment step includes: the temperature is raised from room temperature to 553-593K at the speed of 3-8K/min, then raised to 753-793K at the speed of 1-2.5K/min and kept for 20-40 min, and finally raised to 1023-1423K at the speed of 3-8K, and the annealing time is 10-20 d. .
In the above scheme, the annealed sample was quenched in ice water.
The lanthanum-iron-silicon-based magnetic refrigeration material prepared according to the scheme is characterized in that the Curie temperature of the lanthanum-iron-silicon-based magnetic refrigeration material is in a room temperature region, and the maximum magnetic entropy change value of the lanthanum-iron-silicon-based magnetic refrigeration material is not lower than 3.50 J.kg under a 2T external magnetic field-1·K-1The full width at half maximum of the entropy change curve is not less than 34.0K.
On the basis of the above-mentioned contents, various modifications, substitutions or alterations can be made to the contents according to ordinary technical knowledge and means in the field without departing from the basic technical idea of the present invention.
The invention discloses a batch method of a wide-temperature-zone large-magnetic-entropy lanthanum-iron-silicon-based room-temperature magnetic refrigeration material for the first time, which adopts a high-energy ball milling-annealing method to prepare the lanthanum-iron-silicon-based room-temperature magnetic refrigeration material with uniform components and stable performance: firstly, a step-by-step ball milling method is adopted to effectively prevent the problems of cold welding and the like caused in the traditional high-energy ball milling process, the powder yield of ball milling is greatly improved under the condition of not adding any grinding aid, and the powder caking phenomenon caused by cold welding is effectively prevented; further combining with an annealing process adopting a gradient temperature rise system, the internal stress formed in the material in the ball milling process is fully released, the problems of material deformation or cracking and the like during quenching are effectively prevented, and the main phase is favorably formed; the Curie temperature of the obtained lanthanum-iron-silicon-based room-temperature refrigeration material is in a room temperature region, and the lanthanum-iron-silicon-based room-temperature refrigeration material can show a wider working temperature region and excellent magnetocaloric performance.
Compared with the prior art, the invention has the beneficial effects that:
1) The invention discloses a preparation method of a wide-temperature-zone large-magnetic-entropy lanthanum-iron-silicon-based room-temperature refrigeration material for the first time, the lanthanum-iron-silicon-based room-temperature magnetic refrigeration material is prepared by adopting a high-energy ball milling-annealing method, the preparation process is simple, the cost is low, the requirement on reaction equipment is not high, and a good foundation can be laid for large-scale preparation and large-scale application of lanthanum-iron-silicon-based materials;
2) The Curie temperature of the lanthanum-iron-silicon-based room temperature refrigeration material prepared by the invention is in a room temperature region, the lanthanum-iron-silicon-based room temperature refrigeration material has a wider working temperature region and excellent magnetocaloric performance, and a new idea can be provided for the preparation of the lanthanum-iron-silicon-based room temperature magnetic refrigeration material with high performance.
Drawings
Fig. 1 is an XRD pattern at room temperature of the products obtained in comparative example 1, comparative example 2, example 1 and example 2 of the present invention.
FIG. 2 is a contrast image of the components of electron probe backscattered electrons (hereinafter, both referred to as BSE images) of the products obtained in example 1 and example 2 of the present invention.
FIG. 3 is a graph showing the change of magnetic entropy with temperature of the products obtained in comparative examples 1 to 2 and examples 1 to 3 of the present invention under a 2T applied magnetic field.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
In the following examples, the purity of the La powder used was 99.5wt.%, and the purity of the Co powder, fe powder and Si powder was 99.9wt.%.
The phase composition analysis of the material was carried out by collecting X-ray diffraction spectra using a powder X-ray diffractometer using a wavelength of
Figure BDA0003712726260000031
The Cu ka 1 characteristic X-ray of (1) was tested.
Microstructural characterization chemical composition analysis was performed using JEOL JXA-8100 Electron Probe Microscopy (EPMA) at 20 kV.
The magnetization curve (M-H curve) and thermomagnetic curve (M-T curve) of the sample were measured using a VersaLab Vibrating Sample Magnetometer (VSM) module (multifunctional VSM manufactured by Quantum Design, usa). The magnetic entropy change Δ S is calculated from the magnetization curve measured by the VSM.
Example 1
A wide-temperature-zone large-magnetic-entropy lanthanum-iron-silicon-based room-temperature magnetic refrigeration material is prepared by the following steps:
1) According to La1.4Fe10.82Co0.98Si1.2Preparing raw materials under the protection of argon atmosphere according to the stoichiometric formula, wherein the total weight of the raw material powder is 8g, and filling the prepared raw materials into a stainless steel ball milling tank;
2) The obtained ball milling tank filled with the raw materials is arranged on a planetary ball mill, the grinding balls are made of stainless steel balls, the ball material ratio is 30: in argon atmosphere, firstly performing ball milling for 12 hours at the rotating speed of 500rpm, wherein the ball milling is stopped for 10 minutes every 1.5 hours, scraping powder from the wall of a tank after the ball milling is finished, and then performing ball milling for 60 minutes at 200 rpm;
after the ball milling is finished, taking out the powder in the ball milling tank under the protection of argon atmosphere, and tabletting and forming the powder under the protection of argon atmosphere, wherein the pressure is 30MPa, and the time is 5min;
3) Laying a layer of refractory cotton at the bottom of the quartz tube, wrapping the molded sample obtained in the step 2) with tantalum foil, putting the wrapped sample into the quartz tube, and vacuumizing to 1 × 10-4Pa, sealing the quartz tube;
4) Putting the sealed quartz tube obtained in the step 3) into a muffle furnace for annealing heat treatment, and specifically comprising the following steps: heating from room temperature to 573K at a rate of 5K/min, heating to 773K at a rate of 2K/min, keeping the temperature for 30min, and heating to 1323K at a rate of 5K/min for 12d; quenching in ice water to obtain the final product (La)1.4Fe10.82Co0.98Si1.2)。
The phase and microstructure analysis of the product obtained in this example is as follows:
the room-temperature XRD pattern of the resultant product was measured using a Cu target X-ray diffractometer, as shown in fig. 1, and the main phase was 12O3. Microstructure characterization chemical composition analysis of the resulting product was performed using EPMA at 20kV, and BSE images are shown in fig. 2, and combined with EDS and phase analysis results, the compositions of these three contrasts, black, gray, white, were determined to be α -Fe phase, 1 phase, and La2O3And (4) phase(s).
The product obtained in this example was tested for its properties as follows:
the isothermal magnetization curve of the resulting product was measured using VSM and expressed according to Maxwell's equations
Figure BDA0003712726260000041
The isothermal magnetic entropy change curve of the obtained product is obtained through calculation, as shown in figure 3, the Curie temperature of the obtained product is 300K, and the magnetic entropy is changed into 4.00 J.kg-1·K-1The working temperature zone is 34.5K. Calculating formula RCP = -Delta S by relative Refrigerating Capacity (RCP)M·δFWHMThe relative refrigerating capacity of the obtained product is 138.0 J.kg-1。
Example 2
A preparation method of a wide-temperature-zone large-magnetic-entropy lanthanum-iron-silicon-based room-temperature magnetic refrigeration material comprises the following specific steps:
1) According to La1.4Fe10.86Co0.94Si1.2Preparing raw materials in a stoichiometric mode under the protection of argon atmosphere, wherein the total weight of raw material powder is 8g, and filling the prepared raw materials into a stainless steel ball milling tank;
2) The obtained ball milling tank filled with the raw materials is arranged on a planetary ball mill, the grinding balls are made of stainless steel balls, the ball-to-material ratio is 30, and the specific ball milling steps are as follows: in argon atmosphere, firstly performing ball milling for 12 hours at the rotating speed of 500rpm, wherein the ball milling is stopped for 10 minutes every 1.5 hours, scraping powder from the wall of a tank after the ball milling is finished, and then performing ball milling for 60 minutes at 200 rpm;
after the ball milling is finished, taking out the powder in the ball milling tank under the protection of argon atmosphere, and tabletting and forming the powder under the protection of argon atmosphere, wherein the pressure is 30MPa, and the time is 5min;
3) Laying a layer of refractory cotton at the bottom of the quartz tube, wrapping the sample formed in the step 2) with tantalum foil, placing the wrapped sample into the quartz tube, and vacuumizing to 1 × 10-4Pa, sealing the quartz tube;
4) Putting the sealed quartz tube obtained in the step 3) into a muffle furnace for annealing heat treatment, and specifically comprising the following steps: heating from room temperature to 573K at a rate of 5K/min, heating to 773K at a rate of 2K/min, keeping the temperature for 30min, and heating to 1323K at a rate of 5K/min for 12d; quenching in ice water to obtain the final product (La)1.4Fe10.86Co0.94Si1.2)。
The phase and microstructure analysis of the product obtained in this example is as follows:
the room-temperature XRD pattern of the resultant product was measured using a Cu target X-ray diffractometer, as shown in fig. 1, and the main phase was 12O3. Microstructure characterization chemical composition analysis of the resulting product was performed using EPMA at 20kV, BSE images are shown in fig. 2, and combined with EDS and phase analysis results, it was determined that the compositions of the three contrasts black, gray, and white were α -Fe phase, 12O3And (4) phase.
The product obtained in this example was tested for its properties as follows:
the isothermal magnetization curve of the sample is measured using VSM and is expressed according to Maxwell's equations
Figure BDA0003712726260000051
The isothermal magnetic entropy change curve of the sample is calculated and obtained, as shown in FIG. 3The Curie temperature of the obtained product is 298K, and the magnetic entropy is changed into 3.63 J.kg-1·K-1The working temperature zone is 35.9K. From a calculation formula of relative Refrigerating Capacity (RCP) = - Δ SM·δFWHMThe relative refrigerating capacity of the obtained product is 130.3 J.kg-1。
Example 3
A wide-temperature-zone large-magnetic-entropy lanthanum-iron-silicon-based room-temperature magnetic refrigeration material comprises the following steps:
1) According to La1.2Fe10.82Co0.98Si1.2Preparing raw materials under the protection of argon gas atmosphere according to the stoichiometric formula, wherein the total weight of the raw material powder is 20g, and filling the prepared raw materials into a stainless steel ball-milling tank;
2) The obtained ball milling tank filled with the raw materials is arranged on a planetary ball mill, the grinding balls are made of stainless steel balls, the ball-to-material ratio is 30, and the specific ball milling steps are as follows: in argon atmosphere, firstly ball-milling for 12h at the rotating speed of 500rpm, wherein the ball-milling is stopped for 10min every 1.5h, scraping powder from the wall of a tank after the ball-milling is finished, and then ball-milling for 60min at 200 rpm;
after the ball milling is finished, taking out the powder in the ball milling tank under the protection of argon atmosphere, and tabletting and forming the powder under the protection of argon atmosphere, wherein the pressure is 30MPa, and the time is 5min;
3) Laying a layer of refractory cotton at the bottom of the quartz tube, wrapping the sample formed in the step 2) with tantalum foil, putting the wrapped sample into the quartz tube, and vacuumizing to 1 × 10-4Pa, sealing the quartz tube;
4) Putting the sealed quartz tube obtained in the step 3) into a muffle furnace for annealing heat treatment, and specifically comprising the following steps: heating from room temperature to 573K at a rate of 5K/min, heating to 773K at a rate of 2K/min, keeping the temperature for 30min, and heating to 1323K at a rate of 5K/min for 12d; quenching in ice water to obtain the final product (La)1.2Fe10.82Co0.98Si1.2)。
The product obtained in this example was tested for its properties as follows:
the isothermal magnetization curve of the sample is measured using VSM and is expressed according to Maxwell's equations
Figure BDA0003712726260000061
The isothermal magnetic entropy change curve of the sample is obtained through calculation, as shown in figure 3, the Curie temperature of the obtained product is 302K, and the magnetic entropy is changed into 3.68 J.kg-1·K-1The working temperature zone is 35.5K. Calculating formula RCP = -Delta S by relative Refrigerating Capacity (RCP)M·δFWHMThe relative refrigerating capacity of the obtained product is 130.6 J.kg-1。
Reducing the rare earth element usage further reduces the cost by reducing z =0.4 to z =0.2 in example 1 and employing the process of the present invention for the release preparation, the curie temperature of the resulting product remains in the room temperature region, with a relative refrigeration capacity comparable to that of the small preparation, indicating that the invention can be used for release preparation.
Comparative example 1
A preparation method of a lanthanum-iron-silicon-based room-temperature magnetic refrigeration material comprises the following specific steps:
1) Press La to1.4Fe10.82Co0.98Si1.2Preparing raw materials in a stoichiometric formula under the protection of argon atmosphere, wherein the total weight of the raw material powder is 8g; the prepared raw materials are put into a stainless steel ball milling tank;
2) Mounting the obtained ball milling tank filled with the raw materials on a planetary ball mill, and setting the ball milling rotation speed at 500rpm for 13 hours; the grinding balls are made of stainless steel balls, and the ball material ratio is 30;
after the ball milling is finished, taking out the powder in the ball milling tank under the protection of argon atmosphere, and tabletting and forming the powder under the protection of argon atmosphere, wherein the pressure is 30MPa and the time is 5min;
3) Laying a layer of refractory cotton at the bottom of the quartz tube, wrapping the sample formed in the step 2) with tantalum foil, putting the wrapped sample into the quartz tube, and vacuumizing to 1 × 10-4Pa, sealing the quartz tube;
4) Putting the sealed quartz tube obtained in the step 3) into a muffle furnace for annealing heat treatment, and specifically comprising the following steps: heating from room temperature to 573K at a rate of 5K/min, heating to 773K at a rate of 2K/min, keeping the temperature for 30min, and heating to 1323K at a rate of 5K/min for 12d; quenching in ice water to obtain the final product (La)1.4Fe10.82Co0.98Si1.2)。
The resultant product was subjected to phase analysis, and as shown in FIG. 1, a large amount of hetero-phases including La2O3Phase and unreacted alpha-Fe phase.
Measuring isothermal magnetization curve of sample by using VSM, and obtaining relation of Maxwell equation
Figure BDA0003712726260000062
The isothermal magnetic entropy change curve of the sample is obtained through calculation, as shown in figure 3, the Curie temperature of the obtained product is 296K, and the magnetic entropy is changed into 2.80 J.kg-1·K-1The working temperature zone is 24.0K. Calculating formula RCP = -Delta S by relative Refrigerating Capacity (RCP)M·δFWHMThe relative refrigerating capacity of the obtained product is 67.2 J.kg-1。
Comparative example 2
A preparation method of a lanthanum-iron-silicon-based room-temperature magnetic refrigeration material comprises the following specific steps:
1) Press La to1.4Fe10.82Co0.98Si1.2Preparing raw materials in a stoichiometric formula under the protection of argon atmosphere, wherein the total weight of the raw material powder is 8g; the prepared raw materials are put into a stainless steel ball milling tank;
2) The obtained ball milling tank filled with the raw materials is arranged on a planetary ball mill, the grinding balls are made of stainless steel balls, the ball material ratio is 30: in argon, firstly, performing ball milling for 12 hours at the rotating speed of 500rpm, wherein the ball milling is stopped for 10 minutes every 1.5 hours, scraping powder from the wall of a tank after the ball milling is finished, and then performing ball milling for 60 minutes at 200 rpm;
after the ball milling is finished, taking out the powder in the ball milling tank under the protection of argon atmosphere, and tabletting and forming the powder under the protection of argon atmosphere, wherein the pressure is 30MPa and the time is 5min;
3) Laying a layer of refractory cotton at the bottom of the quartz tube, wrapping the sample formed in the step 2) with tantalum foil, putting the wrapped sample into the quartz tube, and vacuumizing to 1 × 10-4Pa, sealing the quartz tube;
4) Putting the sealed quartz tube obtained in the step 3) into a muffle furnace for annealing and heat treatmentThe method specifically comprises the following steps: heating to 1323K from room temperature at the speed of 5K/min, and annealing for 12d; quenching in ice water to obtain the final product (La)1.4Fe10.82Co0.98Si1.2)。
Measuring isothermal magnetization curve of sample by using VSM, and obtaining relation of Maxwell equation
Figure BDA0003712726260000071
The isothermal magnetic entropy change curve of the sample is obtained through calculation, as shown in FIG. 3, the Curie temperature of the obtained product is 301K, and the magnetic entropy is changed into 3.50 J.kg-1·K-1The working temperature zone is 36.3K. From a calculation formula of relative Refrigerating Capacity (RCP) = - Δ SM·δFWHMThe relative refrigerating capacity of the obtained product is 127.1 J.kg-1。
The above embodiments are only examples for clearly illustrating the present invention and are not intended to limit the present invention. Other variants and modifications of the invention, which are obvious to those skilled in the art and can be made on the basis of the above description, are not necessary or exhaustive for all embodiments, and are therefore within the scope of the invention.

Claims (10)

1. A preparation method of a wide-temperature-zone large-magnetic-entropy lanthanum-iron-silicon-based room-temperature magnetic refrigeration material is characterized in that La, fe, co and Si powder are used as raw materials, the raw materials are subjected to high-energy ball milling under a protective atmosphere, and then pressing and annealing heat treatment are carried out.
2. The preparation method of claim 1, wherein the lanthanum-iron-silicon-based room-temperature magnetic refrigeration material has a stoichiometric formula of La1+zFe13-x-yCoxSiyWherein x is more than or equal to 0.88 and less than or equal to 1.06, y is more than or equal to 0.8 and less than or equal to 1.4, and z is more than or equal to 0 and less than or equal to 0.8.
3. The preparation method according to claim 1, wherein the preparation method is carried out under a protective atmosphere, and specifically comprises the following steps:
1) Taking La powder, fe powder, co powder and Si powder as raw materials, and weighing the raw materials according to the stoichiometric ratio of the lanthanum-iron-silicon-based magnetic refrigeration material;
2) Performing high-energy ball milling on the weighed raw materials to prepare intermetallic compound powder;
3) Tabletting and molding the intermetallic compound powder obtained in the step 2);
4) And (3) packaging the sample obtained in the step 3) in a quartz tube, and carrying out annealing heat treatment and quenching to obtain the lanthanum-iron-silicon-based magnetic refrigeration material.
4. The method according to claim 3, wherein the atmosphere is a vacuum condition or an inert gas atmosphere.
5. The method of claim 3, wherein the high energy ball milling step comprises: firstly, ball-milling for 10-24 h at the rotating speed of 300-600 rpm, wherein the ball-milling is stopped for 5-20 min every 1-2 h; then the powder is scraped from the wall of the tank and finally ball milled for 30-90 min at the rotating speed of 50-250 rpm.
6. The preparation method according to claim 3, wherein the high-energy ball milling is carried out under a protective atmosphere, and the ball-to-material ratio is (20-40): 1.
7. The process according to claim 3, wherein the pressure used in the tablet-forming step is 10 to 50MPa and the dwell time is 3 to 10min.
8. The method of claim 3, wherein the shaped sample obtained in step 3) is further hermetically wrapped with a tantalum foil or a molybdenum foil.
9. The method of manufacturing according to claim 3, wherein the annealing heat treatment step includes: firstly heating from room temperature to 553-593K at the speed of 3-8K/min, then heating to 753-793K at the speed of 1-2.5K/min and preserving heat for 20-40 min, and finally heating to 1023-1423K at the speed of 3-8K, wherein the annealing time is 10-20 d.
10. The lanthanum-iron-silicon-based magnetic refrigeration material prepared by the preparation method of any one of claims 1 to 9, characterized in that the Curie temperature is in a room temperature region, and the maximum magnetic entropy change value under a 2T external magnetic field is not less than 3.50J-kg-1·K-1The full width at half maximum of the entropy change curve is not less than 34.0K.
CN202210729804.XA 2022-06-24 2022-06-24 Wide-temperature-zone large-magnetic-entropy lanthanum-iron-silicon-based room-temperature magnetic refrigeration material and preparation method thereof Pending CN115274236A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116426809A (en) * 2023-03-22 2023-07-14 华南理工大学 High-strength La-Fe-Si based magnetic refrigeration composite material and preparation method thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116426809A (en) * 2023-03-22 2023-07-14 华南理工大学 High-strength La-Fe-Si based magnetic refrigeration composite material and preparation method thereof

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