An extremely low temperature magnetic refrigeration material, a preparation method and application thereof

Abstract

The application belongs to the technical field of magnetic refrigeration materials, and particularly relates to an extremely low-temperature magnetic refrigeration material and a preparation method and application thereof. The preparation method of the extremely low-temperature magnetic refrigeration material comprises the following steps: taking EuCl3 solution as cathode liquid, taking H2SO4 solution as anode liquid, performing diaphragm electrolysis, adding carbonate solution to the cathode zone after electrolysis is completed, generating a precipitate, filtering, and preparing the extremely low-temperature magnetic refrigeration material. The extremely low-temperature magnetic refrigeration material prepared by the application exhibits large magneto-caloric effect near 1K, and has simple preparation process, short cycle, and is suitable for industrial production. The application of the extremely low-temperature magnetic refrigeration material is not only beneficial to the development of the fields of condensed state physics, dark matter search, quantum information science and space exploration in China, but also helps to promote the high-value utilization of rare earth resources in China, and improve the rare earth technology level and industrial competitiveness in China.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of magnetic refrigeration materials, and particularly relates to an extremely low-temperature magnetic refrigeration material and a preparation method and application thereof. BACKGROUND

[0002] The extremely low-temperature refrigeration technology has very important strategic significance in the fields of condensed matter physics, dark matter search, quantum information science and space exploration. The extremely low-temperature is generally obtained by 3He adsorption refrigeration and 3He-4He dilution refrigeration. However, both of the two refrigeration methods rely on the scarce 3He resource, which is mainly produced from the by-product of tritium radioactivity decay in nuclear reactors or nuclear weapon stockpiles. The United States and Russia have reduced the tritium reserves, making the 3He resource even more scarce. The magnetic refrigeration technology does not rely on the 3He resource, is not limited by gravity, and has the advantages of energy saving and high efficiency, and is an ideal choice to replace the existing extremely low-temperature refrigeration technology.

[0003] The magnetic refrigeration material is the basis of the magnetic refrigeration technology, and the development of giant magneto-thermal effect materials with large magnetic entropy change, high refrigeration capacity, stability and reliability and easy mass production is the key to the development of the magnetic refrigeration technology. In recent years, rare earth non-metallic materials have become one of the focuses of research in the field of magnetic refrigeration materials due to their simple preparation process, stability and reliability, large-scale production, easy forming and processing, and low cost. The development of rare earth non-metallic material systems with giant magneto-thermal effect at extremely low temperature not only helps to promote the development of the extremely low-temperature application field in China, but also helps to promote the high-value utilization of rare earth resources in China, and improves the competitiveness and technical level of the rare earth industry in China. Considering the actual application, the larger the external field applied to the refrigerant, the higher the cost of the magnet required, so the low-field magneto-thermal effect has more application prospects.

[0004] CN108840364A discloses an inorganic gadolinium-based complex crystal and a preparation method thereof. The crystal has a maximum magnetic entropy change of about 49.0 J·kg -1 ·K -1 under the change of a magnetic field of 0-5T, and is a good magnetic refrigeration material. However, the crystal material needs to be crystallized in a stainless steel high-pressure reaction container with a polytetrafluoroethylene reaction kettle at a temperature of 180℃ for 7 days, and the preparation period is long and the energy consumption is large, which is not suitable for industrial production.

[0005] CN112175587A discloses a gadolinium carbonate dihydrate and its application in the field of magnetic refrigeration. The maximum magnetic entropy change thereof is about 55.2 J·kg -1 ·K -1The magnetic entropy value under the commercial magnetic field condition is higher than that of the existing commercial magnetic refrigeration material. However, the technology needs to be dried for 24 hours after being kept at 120 DEG C for 5 hours in a stainless steel high-pressure reaction container with a polytetrafluoroethylene reaction kettle as an inner liner, so as to obtain a crystal with good crystallinity. The material has a long preparation period and contains crystal water, which is easy to lose and deteriorate, thereby limiting its practical application.

[0006] CN104559944A discloses a rare earth-containing hydroxide magnetic refrigeration material and a preparation method thereof. The composition of the magnetic refrigeration material is Gd(OH) 8 / 3 C l1 / 3 The maximum magnetic entropy change of the material is up to 60.0 J·kg -1 ·K -1 ·K -1 ·K -1 However, the maximum magnetic entropy change of the material under the change of the magnetic field of 0-2T is only 14.0 J·kg -1 ·K -1 The use of a large amount of hydrochloric acid and sodium hydroxide in the preparation process inevitably causes environmental pollution. The product is obtained through a hydrothermal reaction at a temperature of 200 DEG C for 2 days, which consumes a large amount of energy and has a long preparation period, and is not suitable for industrial production.

[0007] Therefore, it is necessary to develop an extremely low-temperature magnetic refrigeration material with large magneto-caloric effect under a lower magnetic field (≤2T) and a simple preparation process, a short period and suitability for industrial production. SUMMARY

[0008] The application aims to provide an extremely low-temperature magnetic refrigeration material, a preparation method and application thereof. The extremely low-temperature magnetic refrigeration material prepared by the application has large magneto-caloric effect near 1K, and has a simple preparation process, a short period and suitability for industrial production. The application of the extremely low-temperature magnetic refrigeration material is not only beneficial to the development of the fields of condensed matter physics, dark matter search, quantum information science and space exploration in China, but also helps to promote the high-value utilization of rare earth resources in China, and improve the rare earth technology level and industrial competitiveness in China.

[0009] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme: a preparation method of an extremely low-temperature magnetic refrigeration material, comprising the following steps:

[0010] A diaphragm electrolysis is performed by taking EuCl3 solution as a cathode solution, taking H2SO4 solution as an anode solution, and separating the cathode solution and the anode solution by an anion exchange film. After the electrolysis is completed, a carbonate solution is added to the cathode area to generate a precipitate, which is filtered to obtain the extremely low-temperature magnetic refrigeration material.

[0011] Preferably, the chemical formula of the extremely low-temperature magnetic refrigeration material is EuCO3, the structure is an orthogonal structure, the space group is Pnma, and the unit cell parameters are a=0.5nm, b=0.5nm and c=1.0nm. α = β = γ = 90°.

[0012] Preferably, the carbonate is at least one of ammonium carbonate, sodium carbonate, potassium carbonate.

[0013] Preferably, the concentration of Eu ions in the EuCl3 solution is 0.1-2 mol / L.

[0014] Preferably, the concentration of the H2SO4 solution is 0.1-0.5 mol / L.

[0015] Preferably, the molar ratio of Eu ions in the EuCl3 solution to carbonate in the carbonate solution is 1:1.

[0016] Preferably, the inert atmosphere comprises nitrogen or argon or a mixture of the two.

[0017] In the present application, the current density selected for the diaphragm electrolysis is 100-1200 A / m 2 . The judgment basis for the completion of electrolysis is that the reduction rate of europium reaches more than 95%.

[0018] The present application also claims a method for preparing the extremely low-temperature magnetic refrigeration material.

[0019] Preferably, the extremely low-temperature magnetic refrigeration material exhibits a magnetocaloric effect near the phase transition temperature, and the magnetic phase transition temperature of the extremely low-temperature magnetic refrigeration material is ≤1.0 K.

[0020] Preferably, the maximum magnetic entropy change of the extremely low-temperature magnetic refrigeration material at 1.3 K temperature when the magnetic field changes from 0 to 1 T is 14.6 J·kg -1 ·K -1 .

[0021] Preferably, the maximum magnetic entropy change of the extremely low-temperature magnetic refrigeration material at 1.3 K temperature when the magnetic field changes from 0 to 2 T is 34.1 J·kg -1 ·K -1 .

[0022] Preferably, the maximum magnetic entropy change of the extremely low-temperature magnetic refrigeration material at 1.3 K temperature when the magnetic field changes from 0 to 5 T is 53.3 J·kg -1 ·K -1 .

[0023] The present application also claims an application of the extremely low-temperature magnetic refrigeration material in the fields of quantum computing and space exploration.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] (1) The phase transition temperature of the extremely low-temperature magnetic refrigeration material prepared by the application is less than or equal to 1.0K; the material exhibits large magnetic heat effect near 1.3K, and the maximum magnetic entropy change under the magnetic field change of 0-1T, 0-2T and 0-5T is 14.6J·kg-1·K-1, 34.1J·kg-1·K-1 and 53.3J·kg-1·K-1 respectively. -1 ·K -1 , which is an extremely low-temperature magnetic refrigeration material with great application potential.

[0026] (2) The extremely low-temperature magnetic refrigeration material EuCO3 provided by the application is prepared by electrolytic reduction and precipitation method, and the preparation process is simple, the period is short, and the material is suitable for industrial production and application. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The XRD pattern of the extremely low-temperature magnetic refrigeration material prepared by the embodiment of the application.

[0028] Figure 2 The schematic diagram of the crystal structure of the extremely low-temperature magnetic refrigeration material prepared by the embodiment of the application.

[0029] Figure 3 The zero-field cooling curve graph of the extremely low-temperature magnetic refrigeration material prepared by the embodiment of the application under the magnetic field of 0.02T and the temperature of 2-300K.

[0030] Figure 4 The zero-field cooling and field cooling curve graph of the extremely low-temperature magnetic refrigeration material prepared by the embodiment of the application under the magnetic field of 0.01T and the temperature of 0.4-2.0K.

[0031] Figure 5 The isothermal magnetization curve graph of the extremely low-temperature magnetic refrigeration material prepared by the embodiment of the application under the temperature of 0.4-1.8K.

[0032] Figure 6 The magnetic entropy change curve graph of the extremely low-temperature magnetic refrigeration material prepared by the embodiment of the application under the temperature of 0.45-1.7K. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the application will be clearly and completely described below in conjunction with the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0034] In the embodiments and comparative examples, the experimental methods used are conventional methods, and the materials, reagents and the like used are commercially available unless otherwise specified.

[0035] Embodiment 1

[0036] The preparation process of the extremely low temperature magnetic refrigeration material EuCO3 is as follows: 25.8323 g of europium chloride (EuCl3) is weighed and dissolved in deionized water to prepare a 1 liter EuCl3 solution; 5.4 mL of concentrated sulfuric acid (98.3% H2SO4) is weighed and dissolved in deionized water to prepare a 1 liter H2SO4 solution; the EuCl3 solution is used as the catholyte and the H2SO4 solution is used as the anolyte, and diaphragm electrolysis is carried out under the protection of inert atmosphere of argon, and the current density is 500 A / m 2 , to obtain EuCl2; (NH4)2CO3 is added to the cathode region to generate a precipitate, which is filtered to obtain the extremely low temperature magnetic refrigeration material.

[0037] Example 2

[0038] The preparation process of the extremely low temperature magnetic refrigeration material EuCO3 is as follows: 25.8323 g of europium chloride (EuCl3) is weighed and dissolved in deionized water to prepare a 0.5 liter EuCl3 solution; 5.4 mL of concentrated sulfuric acid (98.3% H2SO4) is weighed and dissolved in deionized water to prepare a 0.5 liter H2SO4 solution; the EuCl3 solution is used as the catholyte and the H2SO4 solution is used as the anolyte, and diaphragm electrolysis is carried out under the protection of inert atmosphere of nitrogen, and the current density is 500 A / m 2 , to obtain EuCl2; (NH4)2CO3 is added to the cathode region to generate a precipitate, which is filtered to obtain the extremely low temperature magnetic refrigeration material.

[0039] Example 3

[0040] The preparation process of the extremely low temperature magnetic refrigeration material EuCO3 is as follows: 258.323 g of europium chloride (EuCl3) is weighed and dissolved in deionized water to prepare a 1 liter EuCl3 solution; 10.8 mL of concentrated sulfuric acid (98.3% H2SO4) is weighed and dissolved in deionized water to prepare a 0.4 liter H2SO4 solution; the EuCl3 solution is used as the catholyte and the H2SO4 solution is used as the anolyte, and diaphragm electrolysis is carried out under the protection of inert atmosphere of nitrogen, and the current density is 1200 A / m 2 , to obtain EuCl2; K2CO3 is added to the cathode region to generate a precipitate, which is filtered to obtain the extremely low temperature magnetic refrigeration material.

[0041] Effect example

[0042] The X-ray powder diffraction analysis of the extremely low temperature magnetic refrigeration material samples prepared in the examples is carried out by using a D8A A25 type X-ray diffractometer (XRD) of Brucker Company.

[0043] Figure 1is the XRD pattern of the extremely low temperature magnetic refrigeration material prepared in Examples 1-3. It can be seen that the XRD pattern of the sample matches well with the standard pattern, indicating that the sample has high phase purity and is composed of a single EuCO3 phase, which belongs to the orthorhombic system and has a space group of Pnma. The schematic diagram of the crystal structure is shown in Figure 2 . The cell parameters obtained by Rietveld refinement are α = β = γ = 90°.

[0044] The samples in Examples 1-3 were tested by using a Quantum Design MPMS3 magnetic measurement system at a temperature range of 2-300 K and an external magnetic field of 0.02 T. The test results of Example 1 are shown in Figures 3-6 .

[0045] Figure 3 is the zero-field cooling (ZFC) curve of the EuCO3 sample prepared in Example 1 at a magnetic field of 0.02 T, and the insert is the first derivative of the curve. It can be seen that no obvious magnetic phase transition of the compound is observed above 2 K, indicating that the phase transition temperature of the compound is below 2 K. Then, the sample was tested by using the MPMS system He3 option-iHelium3 at a temperature range of 0.4-2.0 K and an external magnetic field of 0.01 T. Figure 4 is the ZFC and FC curve of the sample at a magnetic field of 0.01 T. It can be seen that the magnetization of the compound first increases and reaches a peak value near 1.0 K, and then rapidly decreases as the temperature decreases, indicating that the compound undergoes a magnetic phase transition near 1.0 K and is a potential extremely low temperature magnetic refrigeration material. Above the phase transition temperature, the ZFC and FC thermomagnetic curves of the material are almost completely coincident, indicating that the magnetic phase transition process is highly reversible and has no thermal hysteresis, which is very important for the practical application of the material.

[0046] Figure 5 is the isothermal magnetization curve of EuCO3 measured at different temperatures of 0.4-1.8 K. As can be seen from the figure, the magnetization of the material rapidly increases with the increase of the external magnetic field at a temperature of 0.4 K, and tends to be saturated at a magnetic field of 5 T. The magnetic entropy change under different magnetic field changes can be calculated according to the isothermal magnetization curve at different temperatures by using the Maxwell relationship. Figure 6 is the curve of the magnetic entropy change of the EuCO3 compound with temperature at a temperature range of 0.45-1.7 K. As can be seen from the figure, the material exhibits large magnetic heat effect near the phase transition temperature. The maximum magnetic entropy changes are 14.6, 34.1 and 53.3 J·kg -1 ·K -1 at a temperature of 1.3 K when the magnetic field changes are 0-1, 0-2 and 0-5 T, respectively. The compound is a very potential extremely low temperature magnetic refrigeration material.

[0047] The above embodiments are only illustrative of the principles and effects of the present application, and are not intended to limit the present application. Any modification or change made by those skilled in the art without departing from the spirit and scope of the present application shall be covered by the claims of the present application.

Claims

1. A method for preparing an ultra-low temperature magnetic refrigeration material, characterized in that, Includes the following steps: Using EuCl3 solution as the cathode and H2SO4 solution as the anolyte, separated by an anion exchange membrane, diaphragm electrolysis is performed under an inert atmosphere. After electrolysis, a carbonate solution is added to the cathode region to generate a precipitate, which is then filtered to obtain the ultra-low temperature magnetic refrigeration material. The inert atmosphere includes nitrogen, argon, or a mixture of both.

2. The method for preparing the ultra-low temperature magnetic refrigeration material as described in claim 1, characterized in that, The chemical formula of the ultra-low temperature magnetic refrigeration material is EuCO3, the structure is orthorhombic, the space group is Pnma, and its unit cell parameters are a=6.03680 Å, b=5.10310 Å, c=8.45310 Å, α=β=γ=90°.

3. The method for preparing the ultra-low temperature magnetic refrigeration material as described in claim 1, characterized in that, The carbonate is at least one of ammonium carbonate, sodium carbonate, and potassium carbonate.

4. The method for preparing the ultra-low temperature magnetic refrigeration material as described in claim 1, characterized in that, It must include at least one of the following (1) to (3): (1) The concentration of Eu in the EuCl3 solution is 0.1~2 mol / L; (2) The concentration of the H2SO4 solution is 0.1~0.5 mol / L; (3) The molar ratio of Eu ions in the EuCl3 solution to carbonate ions in the carbonate solution is 1:

1.

5. The method for preparing the ultra-low temperature magnetic refrigeration material according to any one of claims 1 to 4, characterized in that, The ultra-low temperature magnetic refrigeration material exhibits a magnetocaloric effect at the phase transition temperature, and the magnetic phase transition temperature of the ultra-low temperature magnetic refrigeration material is ≤1.0K.

6. The method for preparing the ultra-low temperature magnetic refrigeration material according to any one of claims 1 to 4, characterized in that, The ultra-low temperature magnetic refrigeration material includes at least one of the following (1) to (3): (1) The maximum magnetic entropy change of the ultra-low temperature magnetic refrigeration material at 1.3K temperature when the magnetic field changes from 0 to 1T is 14.6 J·kg. -1 ·K -1 ; (2) The maximum magnetic entropy change of the ultra-low temperature magnetic refrigeration material at 1.3K when the magnetic field changes from 0 to 2T is 34.1 J·kg. -1 ·K -1 ; (3) The maximum magnetic entropy of the ultra-low temperature magnetic refrigeration material at 1.3K temperature when the magnetic field changes from 0 to 5T is 53.3 J·kg. -1 ·K -1 .

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