Cold storage material as well as preparation method and application thereof
By developing Gd2O2Se crystal as a cooling material, the problem of insufficient specific heat at the liquid helium temperature in the prior art was solved, and high specific heat performance in the 1-10K temperature zone was achieved, which significantly improved the performance of the refrigerator.
Patent Information
- Application Number
- CN202411672445.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-21
- Publication Date
- 2025-04-04
AI Technical Summary
The lack of high-performance cooling materials suitable for liquid helium temperatures and have significant magneto-thermal effects, resulting in a trough of specific heat capacity between 6-7K, affecting the performance of the refrigerator.
A cooling material including Gd2O2Se crystal was developed, and Gd2O2Se crystals with significant magnetothermal effects were prepared by mixing Gd2O3, Se, activated carbon powder, CsCl and iodine element particles in a specific ratio and sintering.
The Gd2O2Se crystal has phase transition around 6.22K and has a large specific heat in the 1-10K temperature zone, which significantly improves the cooling performance at the liquid helium temperature and fills the defect of the trough of specific heat capacity between 6-7K.
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Figure CN119750504A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of cold storage technology, and in particular to a cold storage material and a preparation method and application thereof. Background Art
[0002] GM (Gifford-Mcmahon) pulse tube refrigerators, especially 4K large-capacity GM pulse tube refrigerators, play a key role in creating and maintaining low-temperature environments and are widely used in condensed matter physics, quantum computing, cryogenic scientific instruments, superconductivity, and military industries. The efficiency of these refrigerators depends largely on the performance of the cold storage device, and the high specific heat material filled inside this component is crucial to the refrigeration performance. However, the specific heat capacity of existing single-element materials decreases with decreasing temperature, and deteriorates greatly when the temperature drops below 10 Kelvin (K), seriously affecting the performance of the refrigerator.
[0003] Magnetic cold storage materials have attracted attention due to their abnormally high specific heat at low temperatures. Materials such as HoCu2, Er3Ni and gadolinium oxysulfide (Gd2O2S, GOS for short) produce magnetic phase transitions below 10K, exhibiting abnormal specific heat characteristics, which can significantly improve the performance of 4K refrigerators and are widely used in commercial refrigerators. Therefore, exploring new low-temperature cold storage materials with high specific heat has become one of the important research directions.
[0004] Rare earth-based compounds, especially those containing elements such as gadolinium (Gd), dysprosium (Dy) and terbium (Tb), exhibit significant magnetocaloric effect due to their unpaired 4f electrons and have the potential for cold storage applications. For example, GOS, as a high-entropy density magnetic cold storage material, is suitable for temperatures ranging from 4.2K to 20K and has been widely used in high-end technology fields such as small regenerative cryogenic gas refrigerators. Although the existing layered filling strategy of HoCu2 and GOS improves the specific heat capacity in the temperature range below 10K, there is a specific heat capacity trough between 6-7K, and new materials need to be studied to fill this range.
[0005] Potential GOS alternative materials, such as gadolinium oxyselenide and gadolinium telluride, have similar physical and chemical properties to GOS. Due to the challenges of their preparation process, the application of rare earth oxyselenides in the field of low-temperature cold storage has not yet been developed. Therefore, it is particularly urgent to develop high-performance cold storage materials with significant magnetocaloric effect at liquid helium temperature, which will promote the practical application of cold storage technology in the liquid helium temperature range and promote the development of cryogenic refrigeration technology. Summary of the invention
[0006] In view of the above-mentioned deficiencies in the prior art, the purpose of the present application is to provide a cold storage material and a preparation method and application thereof, aiming to solve the problem in the prior art of the lack of high-performance cold storage materials suitable for liquid helium temperature and having a significant magnetocaloric effect.
[0007] The technical solution of this application is as follows:
[0008] In a first aspect of the present application, a cold storage material is provided, wherein the cold storage material comprises Gd2O2Se crystals.
[0009] Optionally, the Gd2O2Se crystal belongs to the trigonal crystal system and the space group is P-3m1.
[0010] Optionally, the unit cell parameters of the Gd2O2Se crystal are α=90°, β=90°, γ=120°,
[0011] The second aspect of the present application provides a method for preparing the cold storage material of the first aspect of the present application, comprising the following steps: mixing Gd2O3, Se, activated carbon powder, CsCl and iodine elemental particles in a predetermined proportion and grinding them to obtain a mixture powder; sintering the mixture powder under vacuum conditions to obtain a cold storage material.
[0012] Optionally, the molar ratio of the Gd2O3, Se and activated carbon powder is 5:5:2.6-5:10:6; the ratio of the mass of the CsCl to the sum of the masses of the Gd2O3, the Se and the activated carbon powder is 3:2; the ratio of the iodine element particles to the sum of the masses of the Gd2O3, the Se and the activated carbon powder is 1:20-10:20.
[0013] Optionally, the specific steps of the sintering treatment include: at an initial temperature of 20-40 degrees Celsius, heating to 950-1100 degrees Celsius within 600-800 minutes at a constant heating rate, keeping warm for 10-48 hours, cooling to 500-750 degrees Celsius after 3-5 days, and finally cooling to room temperature within 10-48 hours.
[0014] The third aspect of the present application provides a use of the cold storage material of the first aspect of the present application in preparing cold storage equipment or refrigeration equipment.
[0015] According to a fourth aspect of the present application, a cold storage device is provided, which includes a first partition member, a second partition member and a third partition member arranged in the cold storage cylinder at intervals, the first partition member, the second partition member and the third partition member being configured to allow ventilation in a direction from the first partition member to the third partition member; the first partition member, the second partition member and the cold storage cylinder form a first accommodating space, and the second partition member, the third partition member and the cold storage cylinder form a second accommodating space; the first accommodating space is filled with a front-stage cold storage material and a middle-stage cold storage material, and the second accommodating space is filled with a rear-stage cold storage material.
[0016] Optionally, the front-stage cold storage material includes at least one of Er3Ni, Pb, Bi, HoCu2, and Ni; the middle-stage cold storage material includes the above-mentioned cold storage materials; and the rear-stage cold storage material includes at least one of the above-mentioned cold storage materials and Gd2O2S.
[0017] Optionally, the phase transition temperatures of the front-stage cold storage material, the middle-stage cold storage material and the rear-stage cold storage material decrease one by one.
[0018] Beneficial effects of the present application: The cold storage material in the present application includes Gd2O2Se crystals, which have a phase transition near 6.22K and have a large specific heat in the 1-10K temperature range, have a significant magnetocaloric effect, and can be used as a cold storage material at liquid helium temperature. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for describing the embodiments are briefly introduced below.
[0020] Figure 1 A schematic diagram of a process for preparing a cold storage material provided in the present application;
[0021] Figure 2 A schematic diagram of the structure of a cold storage device provided in this application;
[0022] Figure 3 A physical picture of a cold storage material provided for this application;
[0023] Figure 4 An optical microscope observation diagram of a cold storage material provided in this application;
[0024] Figure 5 A schematic diagram of the crystal structure of a cold storage material provided in this application;
[0025] Figure 6 An X-ray diffraction test diagram of a powder of a cold storage material provided in this application;
[0026] Figure 7 This is a curve showing the change in specific heat-temperature data of a cold storage material provided in this application.
[0027] Figure Number:
[0028] 100. Cold storage equipment; 1. Cold storage cylinder; 21. First partition member; 22. Second partition member; 23. Third partition member; 31. Front cold storage material; 32. Middle cold storage material; 33. Rear cold storage material; 41. Air inlet; 42. Air outlet; 51. First accommodating space; 52. Second accommodating space. DETAILED DESCRIPTION
[0029] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the drawings and embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present application. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.
[0030] It should be noted that if there are descriptions involving "first", "second", etc. in the implementation of this application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance and implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that ordinary technicians in the field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.
[0031] The embodiment of the present application provides a cold storage material, including Gd2O2Se crystals. Among them, the Gd2O2Se crystals have a phase transition near 6.22K and have a large specific heat in the temperature range of 1-10K. There is no application of rare earth selenides in the field of low-temperature cold storage in the prior art. The Gd2O2Se crystals have a significant magnetocaloric effect and can be used as a cold storage material at liquid helium temperature.
[0032] In some embodiments, the Gd2O2Se crystal belongs to the trigonal system and the space group is P-3m1.
[0033] In some embodiments, the Gd2O2Se crystal unit cell parameters are α=90°, β=90°, γ=120°,
[0034] The present application also provides a method for preparing the cold storage material as described above, comprising the steps of:
[0035] Gd2O3, Se, activated carbon powder, CsCl and iodine particles are mixed in a certain proportion and ground to obtain a mixture powder;
[0036] The mixture powder is sintered under vacuum conditions to obtain a cold storage material.
[0037] In some embodiments, the molar ratio of Gd2O3, Se and activated carbon powder is 5:5:2.6-5:10:6, for example, the molar ratio of Gd2O3, Se and activated carbon powder is 5:5:2.6, 5:5:5, 5:6:5, 5:8:6 or 5:10:5, etc. The ratio of the mass of CsCl to the sum of the mass of Gd2O3, Se and activated carbon powder is 3:2-3:5. For example, the ratio of the mass of CsCl to the sum of the mass of Gd2O3, Se and activated carbon powder is 3:2, 3:3, 3:4 or 3:5, etc. The ratio of the iodine particles to the sum of the masses of Gd2O3, Se and activated carbon powder is 1:20-10:20. For example, the ratio of the iodine particles to the sum of the masses of Gd2O3, Se and activated carbon powder is 1:20, 2:20, 3:20, 4:20, 6:20, 8:20, 9:20 or 10:20, etc.
[0038] In some embodiments, the specific steps of the sintering treatment include: at an initial temperature of 20-40 degrees Celsius, heating to 950-1100 degrees Celsius within 600-800 minutes at a constant heating rate, keeping the temperature for 10-48 hours, cooling to 500-750 degrees Celsius after 3-5 days, and finally cooling to room temperature within 10-48 hours.
[0039] In some embodiments, see Figure 1 The preparation method of the cold storage material comprises the following steps:
[0040] S1: Gd2O3 powder, Se powder, activated carbon powder, CsCl powder and iodine (I2) particles are uniformly mixed in a certain proportion and ground to obtain a mixture powder.
[0041] Among them, the molar ratio of Gd2O3, Se and activated carbon powder is 5:5:2.6-5:10:6, the ratio of the mass of CsCl to the sum of the mass of Gd2O3, Se and activated carbon powder is 3:2, and the ratio of the iodine element particles to the sum of the mass of Gd2O3, Se and activated carbon powder is 1:20-10:20.
[0042] The addition amount of Gd2O3 powder, Se powder and activated carbon powder will affect the phase composition of the product. When the molar ratio is lower than the above, it will be difficult to synthesize the desired phase. When the addition amount is too much and higher than the molar ratio, impurities will be generated. CsCl powder is a co-solvent and will affect the phase synthesis. I2 particles are used to control the growth rate and produce the atmosphere required for synthesis, which affects the phase synthesis.
[0043] S2: filling the mixture powder into a quartz tube and performing vacuum sealing treatment to obtain a mixture reaction vacuum quartz tube.
[0044] Among them, the thickness of the quartz tube is more than 1 mm, the outer diameter is 20 mm, and the sealing tube height is 100-200 mm.
[0045] S3: placing the mixture reaction vacuum quartz tube in a high temperature heating furnace for high temperature reaction and sintering.
[0046] The sintering temperature is set as follows: initial temperature 20-40 degrees Celsius, heating to 950-1100 degrees Celsius after 600-800 minutes; keeping at 950-1100 degrees Celsius for 10-48 hours, cooling to 500-750 degrees Celsius after 3-5 days; cooling from 500-750 degrees Celsius to room temperature after 10-48 hours.
[0047] The melting and mixing of reactants is controlled by controlling the heating time and temperature. If the temperature is lower than the above range, the melting and mixing of reactants will be insufficient, while if the temperature is too high, there will be safety risks. The crystal growth is controlled by controlling the holding time, cooling time and cooling temperature. If the temperature is too low, the product will be difficult to synthesize.
[0048] S4: The sintered product is ultrasonically cleaned to obtain the low-temperature cold storage Gd2O2Se crystal.
[0049] Among them, the ultrasonic cleaning time is set to 24-72 hours, and the ultrasonic cleaning solution is ultrapure water.
[0050] The embodiment of the present application also provides a use of the cold storage material as described above in the preparation of cold storage equipment or refrigeration equipment.
[0051] See also Figure 2The embodiment of the present application also provides a cold storage device 100, which generally includes a cold storage cylinder 1 and a first partition member 21, a second partition member 22 and a third partition member 23 arranged at intervals in the cold storage cylinder 1. Among them, the first partition member 21, the second partition member 22 and the third partition member 23 are configured to ventilate in the direction from the first partition member 21 to the third partition member 23 (direction F), the first partition member 21 forms an air inlet 41, and the third partition member forms an exhaust port 42. The first partition member 21, the second partition member 22 and the cold storage cylinder 1 form a first accommodating space 51, and the second partition member 22, the third partition member 23 and the cold storage cylinder 1 form a second accommodating space 52; the first accommodating space 51 is filled with a front-stage cold storage material 31 and a middle-stage cold storage material 32, and the second accommodating space 52 is filled with a rear-stage cold storage material 33. In one embodiment, the front-stage cold storage material 31 and the middle-stage cold storage material 32 in the first space 51 can be mixed in proportion or used separately or placed without mixing.
[0052] In some embodiments, the front-stage cold storage material 31 includes at least one of Er3Ni, Pb, Bi, HoCu2, and Ni; the middle-stage cold storage material 32 includes the cold storage material described above; and the rear-stage cold storage material 33 includes at least one of the cold storage material described above and Gd2O2S.
[0053] Furthermore, the phase transition temperatures of the front-stage cold storage material 31 , the middle-stage cold storage material 32 , and the rear-stage cold storage material 33 decrease one by one.
[0054] When the refrigerant gas flows into the cold storage device 100 through the air inlet 41, it exchanges heat with the secondary cold storage materials (the front cold storage material 31, the middle cold storage material 32, and the rear cold storage material 33) inside the cold storage device 100, and then is discharged from the exhaust port 42. In this process, the refrigerant gas transfers its own heat to the secondary cold storage material, and further cools down in different proportions of the secondary cold storage material.
[0055] The following will provide further explanation through specific examples.
[0056] Example 1
[0057] S1. Gd2O3 powder, Se powder, activated carbon powder, CsCl powder and iodine (I2) particles are uniformly mixed in a certain proportion and ground to obtain a mixture powder. The molar ratio of Gd2O3, Se and activated carbon powder is 5:7:2.6, the ratio of the mass of CsCl to the sum of the mass of Gd2O3, Se and activated carbon powder is 3:2, and the ratio of the mass of iodine particles to the sum of the mass of Gd2O3, Se and activated carbon powder is 3:20.
[0058] S2. Filling the mixture powder into a quartz tube and performing vacuum sealing treatment to obtain a mixture reaction vacuum quartz tube.
[0059] S3. Place the mixture reaction vacuum quartz tube in a high temperature heating furnace for high temperature reaction and sintering. The specific temperature setting is: at an initial temperature of 30 degrees Celsius, heat up to 1050 degrees Celsius within 600 minutes at a constant heating rate, and keep warm for 24 hours, then cool down to 700 degrees Celsius after 3 days, and finally cool down to room temperature within 24 hours.
[0060] S4. The sintered product is ultrasonically cleaned with ultrapure water for 24 hours to obtain Gd2O2Se crystals (cold storage material).
[0061] Example 2
[0062] S1. Gd2O3 powder, Se powder, activated carbon powder, CsCl powder and iodine (I2) particles are uniformly mixed in a certain proportion and ground to obtain a mixture powder. The molar ratio of Gd2O3, Se and activated carbon powder is 5:5:2.6, the ratio of the mass of CsCl to the sum of the mass of Gd2O3, Se and activated carbon powder is 3:2, and the ratio of the mass of iodine particles to the sum of the mass of Gd2O3, Se and activated carbon powder is 1:20.
[0063] S2. Filling the mixture powder into a quartz tube and performing vacuum sealing treatment to obtain a mixture reaction vacuum quartz tube.
[0064] S3. Place the mixture reaction vacuum quartz tube in a high-temperature heating furnace for high-temperature reaction and sintering. The specific temperature setting is: at an initial temperature of 20 degrees Celsius, heat up to 950 degrees Celsius within 600 minutes at a constant heating rate, and keep warm for 48 hours, then cool down to 700 degrees Celsius after 3 days, and finally cool down to room temperature within 10 hours.
[0065] S4. The sintered product is ultrasonically cleaned with ultrapure water for 24 hours to obtain Gd2O2Se crystals (cold storage material).
[0066] Example 3
[0067] S1. Gd2O3 powder, Se powder, activated carbon powder, CsCl powder and iodine (I2) particles are uniformly mixed in a certain proportion and ground to obtain a mixture powder. The molar ratio of Gd2O3, Se and activated carbon powder is 5:10:6, the ratio of the mass of CsCl to the sum of the mass of Gd2O3, Se and activated carbon powder is 3:2, and the ratio of the mass of iodine particles to the sum of the mass of Gd2O3, Se and activated carbon powder is 10:20.
[0068] S2. Filling the mixture powder into a quartz tube and performing vacuum sealing treatment to obtain a mixture reaction vacuum quartz tube.
[0069] S3. Place the mixture reaction vacuum quartz tube in a high temperature heating furnace for high temperature reaction and sintering. The specific temperature setting is: at an initial temperature of 40 degrees Celsius, heat up to 1100 degrees Celsius within 800 minutes at a constant heating rate, and keep warm for 24 hours, then cool down to 500 degrees Celsius after 5 days, and finally cool down to room temperature within 48 hours.
[0070] S4. The sintered product was ultrasonically cleaned with ultrapure water for 72 hours to obtain Gd2O2Se crystals (cold storage material).
[0071] Test Example 1
[0072] The composition and crystal structure analysis experiment of the Gd2O2Se crystal prepared in Example 1 was carried out.
[0073] (1) The prepared Gd2O2Se crystals were structurally characterized.
[0074] like Figure 3 As shown, under the microscope observation of the testing instrument Bruker D8 VENTURE single crystal diffractometer, the crystal exhibits the appearance characteristics of a transparent hexagonal prism and has the corresponding crystal face characteristic structure;
[0075] like Figure 4 As shown, under optical microscope observation, the crystals exhibit transparent crystal structure characteristics;
[0076] like Figure 5 As shown, the structure of the Gd2O2Se crystal was tested under the test conditions of the test instrument Bruker D8 VENTURE single crystal diffractometer, Mo target, Kα radiation source (wavelength = 0.07107 nm), and the test temperature was 100K, and the structure was analyzed by Olex2 software. The obtained Gd2O2Se crystal data is shown in Table 1;
[0077] Table 1 Gd2O2Se crystal data parameters
[0078]
[0079]
[0080] (2) Characterize the composition of the prepared Gd2O2Se crystals.
[0081] The obtained Gd2O2Se crystal powder was tested using a Rigaku SmartLab 9KW model powder X-ray diffractometer. The results are shown in Figure 6The obtained spectrum is basically consistent with the standard XRD spectrum, proving that the single crystal powder of the target Gd2O2Se has been prepared.
[0082] Test Example 2
[0083] The performance of the Gd2O2Se crystal prepared in Example 1 was tested.
[0084] The specific heat data of the crystal sample prepared in Example 1 was measured using comprehensive physical property measurement (PPMS). The single crystal sample prepared in Example 1 was fixed on a specific heat table with low temperature glue for data testing. When the magnetic field was 0T, the specific heat (C p ) changes with temperature. To study the contribution of the specific heat brought by the magnetic phase transition in Gd2O2Se, a double Debye fitting was performed on the data from 24-50K, and the fitted curve was extended to 1.8K to obtain the value of the phonon specific heat. The value of the magnetic specific heat is obtained by subtracting the phonon specific heat data obtained by fitting from the specific heat data obtained by the test. Figure 7 The specific heat temperature curve is shown. It can be seen that there is an obvious phase transition near 6.22K, and it has a large specific heat in the temperature range of 1-10K, with a specific heat peak of 55.48J / mol 3 K. And when the magnetic field gradually increases, the phase change is gradually suppressed, showing a high degree of cold storage availability.
[0085] In summary, the cold storage material in the present application includes Gd2O2Se crystals. Gd2O2Se crystals have a phase transition near 6.22K, and have a large specific heat in the temperature range of 1-10K. They have a significant magnetocaloric effect and can be used as a cold storage material at liquid helium temperature. The preparation method of the cold storage material in the present application uses a co-solvent method to grow crystals, which is simple to operate, the raw materials are easy to obtain, and the experimental safety factor is high. The obtained cold storage material has the advantages of stable physicochemical properties, good mechanical properties, not easy to deliquesce, and easy to store, which is conducive to subsequent processing and application. The cold storage equipment in the present application combines and places materials with different multi-end specific heat characteristics inside the secondary cold storage device. The phase transition temperature of the cold storage materials in the front, middle and rear sections decreases, and the gas flows through the cold storage device. A multi-end cooling program can occur, and ultimately a more efficient refrigeration of the secondary cold storage device is achieved.
[0086] It should be understood that the application of the present application is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to this application.
Claims
1. A cold storage material, characterized in that: The cold storage material includes Gd2O2Se crystals.
2. The cold storage material according to claim 1, characterized in that: The Gd2O2Se crystal belongs to the trigonal system and has a space group of P-3m1.
3. The cold storage material according to claim 1, characterized in that: The unit cell parameters of the Gd2O2Se crystal are α=90°, β=90°, γ=120°, 4. A method for preparing the cold storage material according to any one of claims 1 to 3, characterized in that: The following steps are involved: Gd2O3, Se, activated carbon powder, CsCl and iodine particles are mixed in a predetermined ratio and ground to obtain a mixture powder; The mixture powder is sintered under vacuum conditions to obtain a cold storage material.
5. The preparation method according to claim 4, characterized in that: The molar ratio of Gd2O3, Se and activated carbon powder is 5:5:2.6-5:10:6; The ratio of the mass of the CsCl to the sum of the mass of the Gd2O3, the Se and the activated carbon powder is 3:2-3:5; The ratio of the iodine element particles to the sum of the masses of the Gd2O3, the Se and the activated carbon powder is 1:20-10:
20.
6. The preparation method according to claim 4, characterized in that: The specific steps of the sintering treatment include: at an initial temperature of 20-40 degrees Celsius, heating to 950-1100 degrees Celsius within 600-800 minutes at a constant heating rate, keeping the temperature for 10-48 hours, cooling to 500-750 degrees Celsius after 3-5 days, and finally cooling to room temperature within 10-48 hours.
7. Use of the cold storage material according to any one of claims 1 to 3 in preparing cold storage equipment or refrigeration equipment.
8. A cold storage device, characterized in that: The cold storage device comprises a first partition member, a second partition member and a third partition member which are arranged in the cold storage cylinder at intervals, and the first partition member, the second partition member and the third partition member are configured to be ventilated in a direction from the first partition member to the third partition member; The first partition member, the second partition member and the cold storage cylinder form a first accommodating space, and the second partition member, the third partition member and the cold storage cylinder form a second accommodating space; The first accommodating space is filled with a front-stage cold storage material and a middle-stage cold storage material, and the second accommodating space is filled with a rear-stage cold storage material.
9. The cold storage device according to claim 8, characterized in that: The front-stage cold storage material includes at least one of Er3Ni, Pb, Bi, HoCu2, and Ni; The middle section cold storage material comprises the cold storage material according to any one of claims 1 to 3; The latter stage cold storage material comprises at least one of the cold storage material according to any one of claims 1 to 3 and Gd2O2S.
10. The cold storage device according to claim 9, characterized in that: The phase transition temperatures of the front-stage cold storage material, the middle-stage cold storage material and the rear-stage cold storage material decrease one by one.