CN-122025322-A - Hexagonal material GdAl3(BO3)4Application in the field of very low temperature magnetic refrigeration

Abstract

The invention discloses application of a hexagonal material GdAl 3 (BO 3 ) 4 in the field of ultralow-temperature magnetic refrigeration, and relates to the technical field of magnetic refrigeration materials. The hexagonal material GdAl 3 (BO 3 ) 4 applied to the field of extremely low temperature magnetic refrigeration provided by the invention can show excellent magnetic thermal performance and stability under extremely low temperature (less than or equal to 300 mK). Gd 3+ is introduced into the material to serve as magnetic ions, and ions with relatively small molecular mass such as Al 3+ and borate ions are used as ligands, so that the mass ratio of the magnetic ions is ensured, and the material has a higher magnetic entropy change value. The phase transition temperature is low, no phase transition occurs at more than 300mK, lambda phase transition occurs at 300mK, and the magnetic entropy is well reserved in an extremely low temperature region. Does not contain crystal water, and has high structural stability and thermal stability. The magnetic refrigerator has obvious magnetocaloric effect in very low temperature area and may be used in magnetic refrigeration in even lower temperature area.

Inventors

• BU HUANPENG
• WU LIUSUO
• GE HAN
• FU YING
• LI FANGLI
• LI JUNYU

Assignees

• 南方科技大学

Dates

Publication Date

20260512

Application Date

20260213

Claims (10)

1. 1. An application of a hexagonal material in the field of extremely low temperature magnetic refrigeration, wherein the chemical formula of the hexagonal material is GdAl 3 (BO 3 ) 4 , and the extremely low temperature is less than or equal to 300mK.
2. 2. The use according to claim 1, characterized in that the spatial group of hexagonal material is R32 (155); and/or the unit cell parameters of the hexagonal material are a=b= 9.2990 a, c= 7.2597 a, α=β=90°, γ=120°.
3. 3. The use according to claim 1, wherein the hexagonal material has a phase transition temperature of 300 ℃ or less mK.
4. 4. The use according to claim 1, wherein the maximum magnetic entropy change of the hexagonal material is not more than 35J-kg -1 ·K -1 under a 0-4 t magnetic field change at a temperature range of 0.5-1.5 k.
5. 5. The use according to claim 1, comprising at least one of (a 1) to (a 4): (a1) Under the condition that the temperature is less than or equal to 1K and the magnetic field is changed by 0-1T, the maximum magnetic entropy change of the hexagonal material is less than or equal to 24.54J.kg -1 ·K -1 ; (a2) Under the condition that the temperature is less than or equal to 1K and the magnetic field change is 0-2T, the maximum magnetic entropy change of the hexagonal material is less than or equal to 32.52J.kg -1 ·K -1 ; (a3) Under the condition that the temperature is less than or equal to 1K and the magnetic field change of 0-3T, the maximum magnetic entropy change of the hexagonal material is less than or equal to 34.05J.kg -1 ·K -1 ; (a4) Under the condition that the temperature is less than or equal to 1K and the magnetic field change of 0-4T, the maximum magnetic entropy change of the hexagonal material is less than or equal to 34.74J.kg -1 ·K -1 .
6. 6. The use according to any of claims 1-5, characterized in that it comprises use in the field of cryogenic physics, deep space exploration, superconductivity, or aerospace and space science.
7. 7. The preparation method of the extremely low temperature magnetic refrigeration material is characterized by comprising the following steps: The Gd-containing compound, the Al-containing compound and the B-containing compound are taken as raw materials, the molar ratio of Gd element to Al element to B element is 1:3 (4-4.2), and the raw materials are weighed, uniformly mixed, placed at 550-650 ℃ for presintering for 2-6 hours, and heated to 1000-1200 ℃ for sintering for 24-48 hours, so that the extremely low temperature magnetic refrigeration material is obtained; The extremely low temperature magnetic refrigeration material is hexagonal, and the chemical formula is GdAl 3 (BO 3 ) 4 .
8. 8. The method for preparing a cryogenic magnetic refrigeration material of claim 7, comprising at least one of (b 1) to (b 8): (b1) The Gd-containing compound comprises at least one of Gd 2 O 3 or Gd powder; (b2) The Al-containing compound includes Al 2 O 3 ; (b3) The B-containing compound includes at least one of H 3 BO 3 , or B 2 O 3 ; (b4) Grinding at least once before or after the sintering step; (b5) The space group of the extremely low temperature magnetic refrigeration material is R32 (155); (b6) The unit cell parameters of the cryogenic magnetic refrigeration material are a=b= 9.2990 a, c= 7.2597 a, α=β=90°, γ=120°; (b7) The phase transition temperature of the extremely low temperature magnetic refrigeration material is less than or equal to 300 mK; (b8) Under the temperature range of 0.5-1.5K and the magnetic field change of 0-4T, the maximum magnetic entropy change of the extremely low temperature magnetic refrigeration material is less than or equal to 35J.kg -1 ·K -1 .
9. 9. Use of a method for the preparation of a cryogenic magnetic refrigeration material as claimed in any one of claims 7 to 8 in the field of cryogenic magnetic refrigeration.
10. 10. An extremely low temperature magnetic refrigeration device, comprising a matrix and an extremely low temperature magnetic refrigeration material, wherein the extremely low temperature magnetic refrigeration material is prepared by the preparation method as claimed in any one of claims 7 to 8.

Description

Application of hexagonal material GdAl 3(BO3)4 in field of ultralow-temperature magnetic refrigeration Technical Field The invention relates to the technical field of magnetic refrigeration materials, in particular to application of a hexagonal material GdAl 3(BO3)4 in the field of very low temperature magnetic refrigeration. Background Very low temperature technology is an important component in scientific research and high-tech applications, especially in the high-end technical fields of condensed state physics, quantum information science, space science and the like. With the increase of the requirements of superconducting quantum computing, deep space exploration and other technologies, the requirements for more efficient and reliable cryogenic refrigeration technologies are also increased. Therefore, how to obtain and maintain a reliable extremely low temperature environment for a long period of time has become one of the core problems restricting the development of the related art. At present, cryogenic refrigeration techniques mainly include dilution refrigeration (Dilution Refrigeration, DR) and adiabatic demagnetization refrigeration (Adiabatic Demagnetization Refrigeration, ADR). Dilution refrigeration technology, while providing a stable cryogenic environment, relies on expensive and scarce helium-3 gas and its complex mechanical structure, limits its applicability to certain environments, particularly in microgravity environments such as space applications. In contrast, the Adiabatic Demagnetization Refrigeration (ADR) technology is used as a solid refrigeration method, refrigeration is realized by utilizing the magnetocaloric effect of a magnetic material in an externally applied magnetic field, and the method has the advantages of compact structure, no dependence on gravity, accurate temperature control and the like, and is more suitable for application in the fields of space, high technology and the like. The core of the adiabatic demagnetization refrigeration technology is greatly dependent on the magnetocaloric effect performance of the magnetic refrigeration material, the efficiency and reliability of the magnetic refrigeration system are also greatly dependent on the magnetocaloric performance of the magnetic refrigeration material under the conditions of low temperature and low magnetic field, and the ideal magnetic refrigeration material has large magnetic entropy change and high thermal efficiency under the conditions of wide temperature area and low magnetic field, such as large magnetic entropy change and good thermal stability in millikelvin (mK) even lower temperature area. However, current magnetic refrigeration materials tend to have limited magnetic entropy change at low temperature and low magnetic field, which limits their application potential in very low temperature refrigeration technology. In the related technology, the material applied to extremely low temperature heat insulation demagnetization refrigeration mainly comprises paramagnetic salt materials, and the material has better magnetic and thermal properties in a certain temperature area, but generally contains a large amount of crystal water, and is easy to lose water under high vacuum or long-term operation conditions, so that the material structure and the magnetic and thermal properties are changed, and the refrigeration effect and the system stability are seriously affected. In addition, the existence of the crystal water can lead the thermal conductivity of the material to be low under the extremely low temperature condition, and auxiliary structures such as metal wires and the like are usually required to be introduced for improving the thermal conductivity, so that the manufacturing difficulty is increased, and the use cost is also obviously increased. On the other hand, paramagnetic salt materials have certain limitations in mechanical strength, chemical stability, processability and the like, and are difficult to meet the comprehensive requirements of a new generation of extremely low-temperature refrigerating device on long-term stable operation, structural reliability and environmental adaptability. In order to solve the above problems, researchers have developed anhydrous inorganic magnetic compounds, multicomponent rare earth compounds, novel structural magnetic material systems, and the like. However, the above materials generally have the problems of insufficient magnetic entropy holding capacity in an ultralow temperature region (for example, less than or equal to 300 mK), poor material stability, high preparation cost, large influence on environment and the like. Therefore, the development of the magnetic refrigeration material which can be applied to the field of extremely low temperature magnetic refrigeration meets the requirements of no crystal water, stable structure, higher efficiency, environmental protection and higher cost efficiency, still has excellent magnetic and thermal properties unde