A rare earth metal hydrogen-rich material and preparation method thereof

Abstract

The present invention discloses a rare earth metal hydrogen-rich material and a preparation method thereof, belonging to the technical field of hydrogen storage materials. The invention is used to solve the problem that the hydrogen content of metal hydrides prepared in the prior art is low; the metal hydrogen-rich materials with high hydrogen content prepared in the prior high-pressure technology cannot be recovered under normal conditions. The chemical formula of the rare earth metal hydrogen-rich material of the present invention is REH 2+x , wherein the value range of x is 1<x≤3; RE is one of the rare earth elements. The rare earth metal hydrogen-rich material REH of the present invention 2+x The high hydrogen content further broadens the material system of hydrogen storage materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen storage materials, and specifically relates to a rare earth metal hydrogen-rich material and a preparation method thereof. Background Art

[0002] Hydrogen is the lightest element in the periodic table. According to the BCS theory, due to the small mass of hydrogen atoms and the higher the electron-phonon coupling strength, the theory predicts that hydrogen will be transformed into atomic metallic hydrogen under high pressure, and it is expected to achieve room temperature superconductor properties. Current research has found that pure hydrogen metalization requires a pressure of at least 500Gpa. In 2004, Ashcroft proposed that in metal hydrogen-rich materials, the hydrogen atoms are "chemically pre-compressed", which is expected to achieve metallic hydrogen properties at lower pressures. In 2015, it was reported that the superconducting transition temperature of H3S at a pressure of 150GPa was 203K. In 2019, experiments reported that LaH 10 The superconducting transition temperature is 250K at a pressure of 267GPa. The above results show that metal hydrides have potential in realizing metallic hydrogen and high-temperature superconductivity. Unfortunately, these metal hydrides are synthesized under extremely high pressure. When the pressure is released to normal pressure, the material will decompose and cannot be used under conventional conditions. Therefore, trying to obtain hydrogen-rich metal materials with high hydrogen content under conventional conditions is a difficult problem that needs to be solved urgently in the current field of hydrogen-based superconductivity.

[0003] On the other hand, the product of hydrogen combustion is water, which is the cleanest energy in the world and is known as the "ultimate energy". Compared with the 1.5MPa hydrogen storage spherical tank, the hydrogen storage density of solid-state hydrogen storage technology is more than 30 times that of the 1.5MPa hydrogen storage tank, and it is also the safest way to store hydrogen. Among them, the hydrogen content in the hydrogen-rich material is an important factor in determining its hydrogen storage density, so increasing the hydrogen content in the hydrogen-rich material has always been one of the difficult problems in the field of hydrogen storage. Summary of the invention

[0004] The purpose of the present invention is to provide a rare earth metal hydrogen-rich material and a preparation method thereof, which are used to solve one of the following technical problems: (1) the metal hydrogen-rich material prepared in the prior art has a low hydrogen content; (2) the metal hydrogen-rich material with a high hydrogen content prepared in the prior high-pressure technology cannot be recovered under conventional conditions.

[0005] The above object of the present invention is achieved through the following technical solutions:

[0006] In one aspect, the present invention provides a rare earth metal hydrogen-rich material, the chemical formula of which is REH 2+x , where the value range of x is 1<x≤3; RE is one of the rare earth elements.

[0007] Furthermore, RE is one of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu.

[0008] On the other hand, the present invention also provides a method for preparing the rare earth metal hydrogen-rich material. The preparation method comprises the steps of maintaining heat and pressure under high pressure and high temperature conditions and then quenching to high pressure and room temperature conditions to obtain the rare earth metal hydrogen-rich material.

[0009] Furthermore, the raw materials of the preparation method include elements RE and H.

[0010] Furthermore, the raw materials of the preparation method include hydrogen source materials and RE-containing raw materials.

[0011] Furthermore, the hydrogen desorption temperature of the hydrogen source material in the preparation method is lower than 700°C.

[0012] Furthermore, the RE-containing raw materials in the preparation method include one or more of rare earth metal elements, rare earth metal dihydrides or rare earth metal trihydrides.

[0013] Furthermore, the pressure under high pressure and high temperature conditions is 1 GPa to 30 GPa.

[0014] Furthermore, the temperature under the high pressure and high temperature conditions is 700 to 1200°C.

[0015] Furthermore, the cooling rate of the quenching treatment is 80-200°C / s.

[0016] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0017] 1) Rare earth metal hydrogen-rich material REH provided by the present invention 2+x Compared with the currently used REH2 and REH3 material systems, the hydrogen content has been increased by 50% to 150%. It is the metal-rich hydride with the highest hydrogen storage energy density that can be stably recovered under normal conditions, further broadening the material system of hydrogen storage materials.

[0018] 2) In the preparation method of the rare earth metal hydrogen-rich material provided by the present invention, the preparation pressure is 1GPa to 30GPa, which is relatively low and easy to achieve; on the other hand, the amount of hydride samples prepared by the diamond anvil cell technology under high pressure is at the micron level and cannot be recovered under conventional conditions. The rare earth metal hydrogen-rich material prepared by the method of the present invention can achieve sample recovery under conventional conditions, and the amplification process is simple and easy. The preparation method of the present invention ensures the repeatability of the experiment and reduces the difficulty of the experiment, becoming an important technology for the application of new metal hydrogen-rich materials.

[0019] 3) The preparation method of the present invention can prepare micron-sized rare earth metal hydrogen-rich materials, and can also prepare large-volume (eg, 3 to 100 cubic millimeters) new hydride materials, and has strong versatility.

[0020] Other features and advantages of the present invention will be described in the following embodiments, and part of them can be obtained from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are only for the purpose of illustrating specific embodiments and are not to be considered as limiting the present invention. The same reference symbols denote the same contents throughout the accompanying drawings.

[0022] Figure 1 YH of Example 1 2+x Comparison of X-ray diffraction spectra with YH2;

[0023] Figure 2 YH of Example 1 2+x Magnetic characterization of materials;

[0024] Figure 3 is LaH in Example 2 2+x The resistivity of the material changes with temperature and the band gap fitting diagram;

[0025] Figure 4 is LuH of Example 3 2+x Graph of the resistance of a material as it changes with temperature;

[0026] Figure 5 is the EuH of Example 4 2+x The resistance of the material changes with temperature and the band gap fitting diagram. DETAILED DESCRIPTION

[0027] Preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used to explain the principles of the present invention together with the embodiments of the present invention.

[0028] The present invention provides a rare earth metal hydrogen-rich material, the chemical formula of which is REH 2+x , where the value range of x is 1<x≤3. For example, the value of x is 1.1, 1.5, 1.8, 2, 2.5, 3.

[0029] Specifically, RE is one of the rare earth elements.

[0030] Specifically, RE can be one of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu.

[0031] Specifically, the REH provided by the present invention 2+x The specific value of x is determined by the change in the unit cell volume. For every additional H atom in the metal hydride unit cell, the unit cell volume increases. The REH of the present invention 2+x By characterizing the crystal structure and obtaining its unit cell volume, and comparing it with the unit cell volume of REH2, the specific value of x can be obtained.

[0032] Specifically, the REH provided by the present invention 2+x The specific value of x can also be roughly determined based on the resistance characterization results.

[0033] Specifically, the rare earth metal hydrogen-rich material REH 2+x It is a semiconductor property.

[0034] The present invention also provides a method for preparing a rare earth metal hydrogen-rich material, wherein the preparation method comprises the steps of maintaining heat and pressure under high pressure and high temperature conditions and then quenching to high pressure and room temperature conditions to obtain REH 2+x This provides convenience for the subsequent research on the physical properties of rare earth metal hydrogen-rich materials under conventional conditions.

[0035] Specifically, the raw materials of the above preparation method include elements RE and H.

[0036] Specifically, the raw materials of the above preparation method include hydrogen source materials and RE-containing raw materials.

[0037] Specifically, considering REH 2+x The preparation temperature is 700-1200°C, and the dehydrogenation temperature of the above hydrogen source material is lower than 700°C.

[0038] Specifically, the above hydrogen source materials include solid hydrogen-containing materials such as boron ammonia complexes, paraffin, and alkaline earth metal calcium hydride.

[0039] Specifically, the RE-containing raw materials include one or more rare earth metal elements, rare earth metal dihydrides, rare earth metal trihydrides, and the like.

[0040] Specifically, the pressure in the above high pressure and high temperature conditions is 1 GPa to 30 GPa. For example, the pressure is 1 GPa, 2 GPa, 3 GPa, 4 GPa, 5 GPa, 6 GPa, 7 GPa, 8 GPa, 9 GPa, 10 GPa, 11 GPa, 12 GPa, 13 GPa, 14 GPa, 15 GPa, 16 GPa, 17 GPa, 18 GPa, 19 GPa, 20 GPa, 21 GPa, 22 GPa, 23 GPa, 24 GPa, 25 GPa, 26 GPa, 27 GPa, 28 GPa, 29 GPa, 30 GPa.

[0041] Specifically, the temperature in the above high pressure and high temperature conditions is 700-1200°C, for example, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C.

[0042] Specifically, the above preparation method can prepare micron-sized rare earth metal hydrogen-rich materials, and can also prepare large-volume (eg, 3 to 100 cubic millimeters) rare earth metal hydrogen-rich materials.

[0043] Specifically, the above preparation method comprises the following steps:

[0044] S1. Encapsulate the hydrogen source material and the RE-containing raw material in an inert metal cylinder, and then place it in a high-pressure chamber;

[0045] S2. Pressurize the hydrogen source material and the raw material containing RE. After reaching the target pressure, start heating and maintain the pressure and temperature.

[0046] S3. Perform quenching treatment under high pressure conditions: quickly lower the temperature of the sample to room temperature, and obtain a rare earth metal hydrogen-rich material after pressure relief.

[0047] Specifically, in S1, the hydrogen source material includes solid hydrogen-containing materials such as boron ammonia complex, paraffin, alkaline earth metal calcium hydride, etc., and the hydrogen decomposition temperature thereof is lower than 700°C.

[0048] Specifically, in S1, the RE-containing raw materials include rare earth metal elements, rare earth metal dihydrides, rare earth metal trihydrides, etc.

[0049] Specifically, in S1, the molar ratio of H atoms to RE in the raw material is 8:1 to 16:1.

[0050] Specifically, in S1, the inert metal cylinder containing the raw materials is made of tantalum, stainless steel, gold, platinum, etc., which is not easy to react with hydrogen and can prevent hydrogen leakage during high-pressure and high-temperature reactions, thereby ensuring a higher hydrogen content in the product.

[0051] Specifically, before S1, the preparation work for high-voltage assembly is completed, including the following steps:

[0052] S01. Select the corresponding high-pressure equipment according to the synthetic pressure of the target material, the high-pressure equipment includes a six-sided top press and a two-stage push press;

[0053] S02. According to the type of high-voltage equipment, select the corresponding high-voltage assembly, including pressure transmission medium, sample chamber, heating component, inert metal cylinder, thermocouple, etc.

[0054] Specifically, in S1, the assembling method of the raw materials includes uniformly mixing the hydrogen source material and the RE-containing raw material.

[0055] Considering the sufficiency of the reaction between hydrogen source materials and rare earth metals and the difficulty of stripping sample by-products, in S1, the raw materials can be assembled in a "sandwich" assembly with hydrogen source materials placed at the bottom and top and RE raw materials placed in the middle.

[0056] Specifically, in S2, the target pressure range is 1 to 30 GPa. For example, the pressure is 1 GPa, 2 GPa, 3 GPa, 4 GPa, 5 GPa, 6 GPa, 7 GPa, 8 GPa, 9 GPa, 10 GPa, 11 GPa, 12 GPa, 13 GPa, 14 GPa, 15 GPa, 16 GPa, 17 GPa, 18 GPa, 19 GPa, 20 GPa, 21 GPa, 22 GPa, 23 GPa, 24 GPa, 25 GPa, 26 GPa, 27 GPa, 28 GPa, 29 GPa, and 30 GPa.

[0057] Specifically, in S2, the target temperature range is 700-1200°C, for example, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C.

[0058] Specifically, in S2, the insulation time is 10 min-4 h, for example, 20 min, 30 min, 40 min, 50 min, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, and 3.5 h.

[0059] Specifically, in S3, the cooling rate of the quenching treatment is 80 to 200°C / s.

[0060] Specifically, in S3, the pressure relief rate is 1 GPa / h to 10 GPa / h, for example, 1.5 GPa / h, 2 GPa / h, 2.5 GPa / h, 3 GPa / h, 3.5 GPa / h, 4 GPa / h, 4.5 GPa / h, 5 GPa / h, 5.5 GPa / h, 6 GPa / h, 6.5 GPa / h, 7 GPa / h, 7.5 GPa / h, 8 GPa / h, 8.5 GPa / h, 9 GPa / h, and 9.5 GPa / h.

[0061] Specifically, the rare earth metal hydrogen-rich material is YH 2+x When (1<x≤3), the pressure under high pressure and high temperature conditions is 12GPa~30GPa, the temperature is 850~1200℃, and the insulation time is 20min~120min.

[0062] Specifically, the rare earth metal hydrogen-rich material is LaH 2+x When (1<x≤3), the pressure under high pressure and high temperature conditions is 14GPa~30GPa, the temperature is 900~1200℃, and the insulation time is 20min~120min.

[0063] Specifically, the rare earth metal hydrogen-rich material is LuH 2+x When (1<x≤3), the pressure under high pressure and high temperature conditions is 15GPa~30GPa, the temperature is 900~1200℃, and the insulation time is 20min~120min.

[0064] Specifically, the rare earth metal hydrogen-rich material is EuH 2+x When (1<x≤3), the pressure under high pressure and high temperature conditions is 14GPa~30GPa, the temperature is 1000~1200℃, and the insulation time is 20min~120min.

[0065] Example 1

[0066] This embodiment provides a rare earth metal hydrogen-rich material YH 2+x (x=1.98~2.97).

[0067] YH in this embodiment 2+x , characterized by its crystal structure, its lattice constant The unit cell volume is The lattice constant of YH2 and the unit cell volume Compared with Since one H atom is added to the unit cell of a metal hydride, the unit cell volume increases. Therefore, YH 2+x The value range of x is 1.98~2.97.

[0068] This embodiment also provides a rare earth metal hydrogen-rich material YH 2+x The preparation method of (x=1.98-2.97) comprises the following steps:

[0069] S1. Encapsulate the hydrogen source material and the RE-containing raw material in an inert metal cylinder, and then place it in a high-pressure chamber;

[0070] S2. Pressurize the hydrogen source material and the raw material containing RE. After reaching the target pressure, start heating and maintain the pressure and temperature.

[0071] S3, quenching treatment is performed under high pressure conditions to quickly reduce the temperature of the sample to room temperature, and a large volume of rare earth metal hydrogen-rich material YH is obtained after pressure relief. 2+x (x=1.98~2.97).

[0072] Specifically, in step S1, the hydrogen source material is a borammane complex.

[0073] Specifically, in step S1, the raw material containing RE is YH2, and the molar ratio of the boroammine complex to YH2 is 2:1.

[0074] Specifically, in step S1, the inert metal cylinder containing the raw material is a gold cylinder.

[0075] Specifically, before step S1, the preparation work for high-voltage assembly is completed, including the following steps:

[0076] S01. Select high pressure equipment 6-8 two-stage push press according to the synthetic pressure of the target material;

[0077] S02. According to the type of high-voltage equipment, select the corresponding high-voltage assembly, including pressure transmission medium, sample chamber, heating component, inert metal cylinder, thermocouple, etc.

[0078] Specifically, in step S1, the raw material assembly method selects a "sandwich" assembly structure in which YH2 is placed in the middle of the metal cylinder and the boroamine complex is placed at both ends.

[0079] Specifically, in step S2, the target pressure is 15 GPa.

[0080] Specifically, in step S2, the target temperature is 1000°C and the holding time is 30 minutes.

[0081] Specifically, in step S3, the cooling rate of the quenching treatment is 150°C / s, and rapid cooling is achieved by controlling the cooling water temperature.

[0082] Specifically, in step S3, the pressure relief rate is 1 GPa / h.

[0083] The YH prepared in this example 2+x The X-ray diffraction spectrum of the sample is Figure 1 As shown in the figure, compared with YH2, the diffraction positions all move toward the low angle direction. Taking the YH2 crystal structure as the initial model, the calculation shows that its unit cell volume increases relative to YH2. Each time a H atom is added to the unit cell, the unit cell volume increases. Therefore, YH in this embodiment 2+x It's YH 3.98～5.97 Compared with YH3 prepared by conventional methods, YH prepared in this example 2+x The H content of the material is significantly improved; compared with the YH4 material prepared at a high pressure of 100 GPa, this invention only needs 15 GPa to prepare YH 3.98～5.97 materials, and can be recovered under conventional conditions and subjected to magnetic characterization, such as Figure 2 As shown, it provides technical support for exploring new application-oriented high-hydrogen content rare earth hydride materials.

[0084] Example 2

[0085] This embodiment provides a rare earth metal hydrogen-rich material LaH 2+x (1<x≤3).

[0086] Specifically, the LaH provided in this embodiment 2+x , characterized by resistance, is a semiconductor property. According to the resistance test results, LaH2 is a metal property. 2+x As the H content in the material increases, the material gradually transforms into a semiconductor. By comparing with LaH3, LaH 2+x The material has a larger band gap, so x>1, such as Figure 3 shown.

[0087] This embodiment provides a rare earth metal hydrogen-rich material LaH 2+x The preparation method of (1<x≤3) comprises the following steps:

[0088] S1. Encapsulate the hydrogen source material and the RE-containing raw material in an inert metal cylinder, and then place it in a high-pressure chamber;

[0089] S2. Pressurize the hydrogen source material and the raw material containing RE. After reaching the target pressure, start heating and maintain the pressure and temperature.

[0090] S3, quenching treatment is performed under high pressure conditions to quickly reduce the temperature of the sample to room temperature, and a large volume of rare earth metal hydrogen-rich material LaH is obtained after pressure relief. 2+x (1<x≤3).

[0091] Specifically, in step S1, the hydrogen source material is calcium hydride.

[0092] Specifically, in step S1, the RE-containing raw material is a La single substance material.

[0093] Specifically, the molar ratio of calcium hydride to metal La is 4:1.

[0094] Specifically, in step S1, the inert metal cylinder containing the raw material is a gold cylinder.

[0095] Specifically, before step S1, the preparation work for high-voltage assembly is completed, including the following steps:

[0096] S01. Select the corresponding high-pressure equipment 6-8 two-stage push press according to the synthetic pressure of the target material;

[0097] S02. According to the type of high-voltage equipment, select the corresponding high-voltage assembly, including pressure transmission medium, sample chamber, heating component, inert metal cylinder, thermocouple, etc.

[0098] Specifically, in step S1, the raw material assembly method selects a "sandwich" assembly structure in which La is placed in the middle of the metal cylinder and the hydrogen source borammane complex is placed at both ends.

[0099] Specifically, in step S2, the target pressure is 20 GPa.

[0100] Specifically, in step S2, the target temperature is 1200°C and the holding time is 30 minutes.

[0101] Specifically, in step S3, the cooling rate of the quenching treatment is 200°C / s, and rapid cooling is achieved by controlling the cooling water temperature.

[0102] Specifically, in step S3, the pressure relief rate is 1 GPa / h.

[0103] The LaH prepared in this example 2+x (x>1) The resistance test of the sample is as follows Figure 3 As shown, compared with LaH2, its resistance is semiconductor property, and compared with LaH3, its band gap is further increased, so the LaH prepared by this method 2+x In the material, x>1. Compared with LaH3 prepared by conventional methods, the LaH prepared in this example 2+x The H content in the material is significantly increased; compared with LaH prepared at high pressure of 160GPa 10 Compared with the materials, this invention only needs 20GPa to prepare LaH 2+x The material can be recycled under normal conditions and characterized by Raman spectroscopy, which provides technical support for exploring new high-hydrogen-content rare earth hydride materials for applications.

[0104] Example 3

[0105] This embodiment provides a rare earth metal hydrogen-rich material LuH 2+x (1<x≤3).

[0106] This embodiment provides a rare earth metal hydrogen-rich material LuH 2+x The preparation method of (1<x≤3) comprises the following steps:

[0107] S1. Encapsulate the hydrogen source material and the RE-containing raw material in an inert metal cylinder, and then place it in a high-pressure chamber;

[0108] S2. Pressurize the hydrogen source material and the raw material containing RE. After reaching the target pressure, start heating and maintain the pressure and temperature.

[0109] S3, quenching treatment is performed under high pressure conditions to quickly reduce the temperature of the sample to room temperature, and a large volume of rare earth metal hydrogen-rich material LuH is obtained after pressure relief. 2+x (1<x≤3).

[0110] Specifically, in step S1, the hydrogen source material is a borammane complex.

[0111] Specifically, in step S1, the RE-containing raw material is metal LuH3.

[0112] Specifically, the molar ratio of the borammane complex to the metal La is 2.5:1.

[0113] Specifically, in step S1, the inert metal cylinder containing the raw material is a gold cylinder.

[0114] Specifically, before step S1, the preparation work for high-voltage assembly is completed, including the following steps:

[0115] S01. Select the corresponding high-pressure equipment 6-8 two-stage push press according to the synthetic pressure of the target material;

[0116] S02. According to the type of high-voltage equipment, select the corresponding high-voltage assembly, including pressure transmission medium, sample chamber, heating component, inert metal cylinder, thermocouple, etc.

[0117] Specifically, in step S1, the raw material assembly method selects a "sandwich" assembly structure in which LuH3 powder is placed in the middle of the metal cylinder and the hydrogen source boroamine complex is placed at both ends.

[0118] Specifically, in step S2, the target pressure is 20 GPa.

[0119] Specifically, in step S2, the target temperature is 1000°C and the holding time is 30 minutes.

[0120] Specifically, in step S3, the cooling rate of the quenching treatment is 100°C / s, and rapid cooling is achieved by controlling the cooling water temperature.

[0121] Specifically, in step S3, the pressure relief rate is 1 GPa / h.

[0122] Figure 4 LuH in this embodiment 2+x The resistance of the material changes with temperature; LuH prepared in this example 2+x (1<x≤3) materials can be recovered under normal conditions and characterized by X-ray structures, providing technical support for exploring new high-hydrogen-content rare earth hydride materials for applications.

[0123] Example 4

[0124] This embodiment provides a rare earth metal hydrogen-rich material EuH 2+x (1<x≤3).

[0125] This embodiment provides a rare earth metal hydrogen-rich material EuH 2+x The preparation method of (1<x≤3) comprises the following steps:

[0126] S1. Encapsulate the hydrogen source material and the RE-containing raw material in an inert metal cylinder, and then place it in a high-pressure chamber;

[0127] S2. Pressurize the hydrogen source material and the raw material containing RE. After reaching the target pressure, start heating and maintain the pressure and temperature.

[0128] S3, quenching treatment is performed under high pressure conditions to quickly reduce the temperature of the sample to room temperature, and a large volume of rare earth metal hydrogen-rich material EuH is obtained after pressure relief. 2+x (1<x≤3).

[0129] Specifically, in step S1, the hydrogen source material is a borammane complex.

[0130] Specifically, in step S1, the RE-containing raw material is metal EuH2.

[0131] Specifically, in step S1, the molar ratio of the borammane complex to EuH2 is 1:1.

[0132] Specifically, in step S1, the inert metal cylinder containing the raw material is a gold cylinder.

[0133] Specifically, before step S1, the preparation work for high-voltage assembly is completed, including the following steps:

[0134] S01. Select the corresponding high-pressure equipment 6-8 two-stage push press according to the synthetic pressure of the target material;

[0135] S02. According to the type of high-voltage equipment, select the corresponding high-voltage assembly, including pressure transmission medium, sample chamber, heating component, inert metal cylinder, thermocouple, etc.

[0136] Specifically, in step S1, the raw material assembly method selects a "sandwich" assembly structure in which EuH2 powder is placed in the middle of the metal cylinder and the hydrogen source borammane complex is placed at both ends.

[0137] Specifically, in step S2, the target pressure is 16 GPa.

[0138] Specifically, in step S2, the target temperature is 1200°C and the holding time is 30 minutes.

[0139] Specifically, in step S3, the cooling rate of the quenching treatment is 100°C / s, and rapid cooling is achieved by controlling the cooling water temperature.

[0140] Specifically, in step S3, the pressure relief rate is 1 GPa / h.

[0141] Figure 5 EuH in this embodiment 2+x The resistance of the material changes with temperature and the band gap fitting diagram. 2+x (1<x≤3) materials can be recovered under normal conditions and subjected to magnetic characterization, providing technical support for the exploration of new high-hydrogen-content rare earth hydride materials for applications.

[0142] The inventor has conducted a large number of experimental studies during the research process, and now uses some solutions with poor effects as comparative examples.

[0143] Comparative Example 1

[0144] This comparative example provides a method for preparing a rare earth metal hydride material. The overall steps are the same as those in Example 1, except that:

[0145] In step S2, the target pressure is 10 GPa, and YH 2.1 .

[0146] Comparative Example 2

[0147] This comparative example provides a method for preparing a rare earth metal hydride material. The overall steps are the same as those in Example 1, except that:

[0148] In step S2, the target temperature is 700°C, and most of the reaction products are raw materials, which means that low temperature is not conducive to the complete reaction of the raw materials.

[0149] Comparative Example 3

[0150] This comparative example provides a method for preparing a rare earth metal hydride material. The overall steps are the same as those in Example 1, except that:

[0151] In step S3, after the high-pressure and high-temperature reaction, no quenching treatment is performed, and the temperature at the location of the sample is slowly lowered to room temperature, and the prepared YH3 has a hexagonal structure.

[0152] Comparative Example 4

[0153] This comparative example provides a method for preparing a rare earth metal hydride material. The overall steps are the same as those in Example 2, except that:

[0154] In step S2, the target pressure is 6 GPa, and LaH3 is prepared.

[0155] Comparative Example 5

[0156] This comparative example provides a method for preparing a rare earth metal hydride material. The overall steps are the same as those in Example 2, except that:

[0157] In step S2, the target temperature is 800°C, and most of the reaction products are raw materials, which means that low temperature is not conducive to the complete reaction of the raw materials.

[0158] Comparative Example 6

[0159] This comparative example provides a method for preparing a rare earth metal hydride material. The overall steps are the same as those in Example 2, except that:

[0160] In step S3, after the high-pressure and high-temperature reaction, no quenching treatment is performed, and the temperature at the location of the sample is slowly lowered to room temperature, and the prepared sample is LaH3.

[0161] Comparative Example 7

[0162] This comparative example provides a method for preparing a rare earth metal hydride material. The overall steps are the same as those in Example 1, except that:

[0163] In S1, the raw material is directly placed in the high pressure chamber. The prepared sample is YH 2.1 ,like Figure 1 shown.

[0164] Comparative Example 8

[0165] This comparative example provides a method for preparing a rare earth metal hydride material. The overall steps are the same as those in Example 1, except that:

[0166] In S3, the cooling rate is 30℃ / s, and the prepared sample is YH 2.1 and a mixed phase of YH3.

[0167] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a rare earth metal hydrogen-rich material, characterized in that: The preparation method can obtain the rare earth metal hydrogen-rich material by quenching to high-pressure room temperature conditions after heat preservation under high-pressure and high-temperature conditions; the pressure under the high-pressure and high-temperature conditions is 12GPa~30GPa, the temperature is 850~1200℃, and the cooling rate of the quenching treatment is 80~200℃ / s; The chemical formula of the rare earth metal hydrogen-rich material is REH 2+x , where the value range of x is 1<x≤3; RE is one of the rare earth elements.

2. The preparation method according to claim 1, characterized in that: RE is one of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu.

3. The preparation method according to claim 1, characterized in that: The raw materials for the preparation method include the elements RE and H.

4. The preparation method according to claim 1, characterized in that: The raw materials of the preparation method include hydrogen source materials and RE-containing raw materials.

5. The preparation method according to claim 1, characterized in that: The hydrogen desorption temperature of the hydrogen source material in the preparation method is lower than 700°C.

6. The preparation method according to claim 1, characterized in that: The RE-containing raw materials of the preparation method include one or more of rare earth metal elements, rare earth metal dihydrides or rare earth metal trihydrides.

7. The preparation method according to claim 1, characterized in that: The pressure under the high pressure and high temperature conditions is 13 GPa~30 GPa.

8. The preparation method according to claim 1, characterized in that: The temperature under the high pressure and high temperature conditions is 900-1200°C.

9. The preparation method according to any one of claims 1 to 8, characterized in that: The cooling rate of quenching treatment is 100~200℃ / s.

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