A lanthanide metal hydride and preparation method thereof
The lanthanide metal element and ammonia borane were cut into sheets by high temperature and high pressure method, and heated and pressurized by a hexagonal top press, which solved the problems of complex preparation process, long periods and high cost in the existing lanthanide metal hydride, and achieved rapid and safe preparation of high-purity lanthanide metal hydride.
Patent Information
- Application Number
- CN202310748048.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-25
- Publication Date
- 2025-05-09
- Estimated Expiration
- 2043-06-25
AI Technical Summary
The preparation process of existing lanthanide metal hydrides has long cycles, harsh conditions, complex steps and high costs, which leads to difficult mass production and easy explosion of hydrogen, which poses safety hazards.
The high-temperature and high-pressure method was used to cut the lanthanide metal element with ammonia borane into sheet shape, and heated and pressurized through a hexagonal top press. The ammonia borane was used to separate hydrogen under high temperature and high pressure, and instead of pure hydrogen, TbH2 and high-purity YbH2 and HoH2 were prepared.
The preparation process is simplified, the preparation cycle is shortened, the preparation cost is reduced, and the safety hazards of hydrogen explosion is avoided. High-purity lanthanide metal hydride is successfully prepared.
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Figure CN116873866B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of preparation of lanthanide metal hydride materials, and in particular to a method for preparing lanthanide metal hydride. Background Art
[0002] Superconducting materials have a series of advantages such as strong current carrying capacity and low loss. Superconducting cables are manufactured by taking advantage of the characteristics of superconductors with zero resistance and no Joule heat generation; superconducting magnetic levitation trains and frictionless superconducting bearings are manufactured by taking advantage of the complete anti-magnetism of superconductors. However, due to the low superconducting transition temperature of traditional superconducting materials, it is difficult to use them on a large scale under conventional conditions. Therefore, finding materials with higher superconducting transition temperatures has become the core goal of current research in the field of superconductivity. Based on the BCS superconductivity theory, Professor Ashcroft found that due to the ultra-high Debye temperature and strong electroacoustic coupling of hydrogen, metallic hydrogen may become a potential room-temperature superconductor, but the synthesis pressure is still unattainable. In 2004, Professor Ashcroft proposed the chemical pre-compression theory, that is, adding other elements to the hydrogen molecular system to stabilize the metallic phase of hydrogen at lower pressure. With the successful confirmation of LaH in high-pressure experiments of rare earth metal elements lanthanum and hydrogen by Drozdov and Somayazulu et al. in 2019, 10 After the superconducting transition at 250K, many researchers began to study rare earth metal hydrides. Kong et al. confirmed that YH6 exhibited a high-temperature superconducting transition at 227K under a pressure of 237GPa, and YH9 exhibited a high-temperature superconducting transition at 243K under a pressure of 201GPa; Troyan et al. confirmed that the superconducting transition temperature of YH6 was about 224K under a pressure of 166GPa. The preparation of lanthanide metal hydrides and the study of their superconducting properties have become a hot topic in this field.
[0003] Although lanthanide metal hydrides have excellent superconducting properties, the preparation process of lanthanide metal hydrides is rigorous and complicated or requires ultra-high pressure. For example, Yunxia Wang et al. used the Sievert method to prepare lanthanide metal hydride YbH using a long preparation cycle. X , that is, a block of ytterbium metal with a purity of 99.9% was used as a precursor to prepare block ytterbium hydride. The ytterbium metal was cut into thin slices (about 1mm×10mm×13mm), mechanically polished with an ultrasonic cleaner and degreased in acetone. The hydrogenation process was carried out using a modified Sievert apparatus. After inserting the metal ytterbium, the equipment was vacuumed at room temperature for 24 hours, and then the sample was vacuumed at 753K (less than 10 -6Pa) annealing for 5 hours. Then high-purity hydrogen with a purity of 99.99999% was introduced into the reaction chamber. In order to prevent the sample from expanding and cracking during the hydrogen absorption process, a very low hydrogenation rate was required, which greatly extended the preparation cycle. Zhang Renfu et al. used a high-temperature direct hydrogenation method and a longer preparation cycle to prepare cerium hydride, that is, firstly, the Ce raw material was cut into cubes of the required size by wire cutting, and then moved into a glove box to grind off the surface oxide layer and clean it, and then the glove box and the tubular furnace were connected, and the tubular furnace was evacuated to vacuum and then purged with argon gas. The air in the tubular furnace was removed three times and the tubular furnace was heated to 900°C and kept warm for 1 hour under vacuum. The cut Ce cube blocks were placed in the tubular furnace, and then hydrogen (200ml / min) was introduced into the tubular furnace to start the hydrogenation reaction. After the hydrogenation reaction was completed, the reactor was cooled to room temperature, and then enough argon was introduced into the furnace to completely discharge the hydrogen in the furnace. Finally, the molybdenum boat containing the sample is taken into the glove box and ground to obtain cerium hydride. The traditional method for preparing lanthanide hydrides has a long preparation cycle, harsh conditions, complex steps, and high costs, which makes it difficult to mass produce lanthanide metal hydrides. In addition, hydrogen is dangerous and easy to explode. Directly introducing hydrogen as a hydrogen source has certain safety hazards. Therefore, it is urgent to develop new preparation processes and methods. Summary of the invention
[0004] The technical problem to be solved by the present invention is to provide a method for preparing lanthanide metal hydrides, so as to solve the problems that the conventional method for preparing lanthanide metal hydrides has a long preparation cycle, harsh conditions, complex steps and high cost, which makes it difficult to mass produce lanthanide metal hydrides, and the hydrogen gas is dangerous and easy to explode.
[0005] In order to solve the above problems, the present invention provides a method for preparing lanthanide metal hydrides, which is characterized by comprising the following steps:
[0006] S1: cutting a lanthanide metal element and ammonia borane into flakes of the same size to obtain a plurality of flakes of lanthanide metal element and flake ammonia borane, stacking them in the order of flake ammonia borane, flake lanthanide metal element, flake ammonia borane, flake lanthanide metal element, and flake ammonia borane, and wrapping them with tantalum foil to obtain a packaged sample;
[0007] S2: The packaged sample obtained in step S1 is placed in a synthesis chamber of a six-sided top press, heated and pressurized, and kept warm and pressurized, and then cooled and depressurized to obtain lanthanide metal hydrides.
[0008] As a preferred solution, in step S1, the lanthanide metal element is one of elemental Yb, elemental Tb and elemental Ho.
[0009] As a preferred solution, when the lanthanide metal single substance is single substance Yb or single substance Ho, the heating temperature is 800°C; when the lanthanide metal single substance is single substance Tb, the heating temperature is 1200°C.
[0010] As a preferred solution, in step S2, the pressurization pressure is 4 GPa, and the heat preservation and pressure holding time is 60-90 minutes.
[0011] As a preferred solution, in step S2, the heating method is heating by generating Joule heat by electrifying the graphite.
[0012] As a preferred solution, the heating method of the chamber is: the packaged sample is heated by energized graphite columns, graphite sheets and graphite tubes, the energized conductive medium is a steel cap and a molybdenum sheet, and the packaged sample is wrapped with a boron nitride tube and a boron nitride sheet.
[0013] The heating uniformity is ensured by the above-mentioned energized graphite heating.
[0014] As a preferred solution, boron nitride is further provided between the packaged sample and the graphite tube.
[0015] As a preferred solution, in step S2, the cooling and depressurizing method is: after stopping the power heating, the sample is naturally cooled to room temperature and then depressurized to normal pressure.
[0016] As a preferred solution, the pressurized pressure transmission medium is pyrophyllite.
[0017] Another technical problem to be solved by the present invention is to provide a method for preparing lanthanide metal hydrides to solve the problem that conventional lanthanide metal hydrides are difficult to mass produce and hydrogen is dangerous and easily exploded.
[0018] In order to solve the above problems, the present invention provides a method for preparing lanthanide metal hydrides, and the lanthanide metal hydrides are prepared by the above preparation method.
[0019] The invention discloses a method for preparing lanthanide metal hydrides, which uses a high temperature and high pressure method to prepare TbH2 and high-purity YbH2 and HoH2. A long preparation period and a complicated preparation process are not required. NH3BH3 (ammonia borane) is decomposed under high temperature and high pressure to release hydrogen, which replaces pure hydrogen as a hydrogen source, eliminates the potential safety hazard of hydrogen explosion, and uses a hinged six-sided press to directly adjust the synthesis pressure and temperature to prepare TbH2 and high-purity YbH2 and HoH2 lanthanide metal hydrides.
[0020] The process flow of the preparation method of a lanthanide metal hydride of the present invention is simple, no complex process and long production cycle are required, there is no safety hazard of hydrogen explosion, and high-purity lanthanide metal hydride is prepared by adjusting temperature and pressure. The preparation method of a lanthanide metal hydride of the present invention greatly reduces the harsh conditions, preparation cost and preparation cycle of the preparation of lanthanide metal hydride, synthesizes TbH2 and high-purity YbH2, HoH2 lanthanide metal hydride, and provides a reference process for the preparation of other lanthanide metal hydrides.
[0021] The present invention has developed a new large-cavity press high-temperature and high-pressure experimental assembly and packaging method, which realizes the high-temperature and high-pressure rapid preparation of lanthanide metal hydrides. The preparation method of the large-cavity press high-temperature and high-pressure method has the advantages of short reaction cycle, mild and controllable reaction conditions, simple steps, etc., and is an ideal synthesis method. The preparation method provided by the present invention is of great significance to promoting the industrial production of lanthanide metal hydrides and other high-temperature and high-pressure preparations of lanthanide metal hydrides. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is the assembly diagram of the high-temperature and high-pressure synthetic block of the domestic hinged six-sided top press used in the experiment;
[0023] Figure 1 Among them, 1. steel cap; 2. molybdenum sheet; 3. graphite column; 4. graphite sheet; 5. magnesium oxide; 6. sample; 7. boron nitride tube and boron nitride sheet; 8. graphite tube; 9. pyrophyllite;
[0024] Figure 2 This is the assembly diagram of the lanthanide metal element and ammonia borane used in the experiment;
[0025] Figure 3 The YbH prepared at different temperatures under the pressure of 4 GPa in Example 1 is x X-ray diffraction pattern of
[0026] Figure 4 The YbH prepared at 4 GPa and 800°C in Example 1 x and standard YbH 2.5 , X-ray diffraction pattern of Yb single substance;
[0027] Figure 5 The TbH prepared at different temperatures under the pressure of 4 GPa in Example 2 is x X-ray diffraction pattern of
[0028] Figure 6 The TbH prepared under the conditions of 4 GPa and 1200°C in Example 2 is x and X-ray diffraction patterns of standard TbH2 and Tb single substance;
[0029] Figure 7 The HoH prepared at different temperatures under the pressure of 4 GPa in Example 3 is x X-ray diffraction pattern of
[0030] Figure 8 The HoH prepared at 4 GPa and 800°C in Example 3 x And the X-ray diffraction patterns of standard HoH2 and Ho elements. DETAILED DESCRIPTION
[0031] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0032] The present invention provides a method for preparing a lanthanide metal hydride, comprising the following steps:
[0033] S1: Cut the lanthanide metal element and ammonia borane into sheets of the same size to obtain a number of sheet-shaped lanthanide metal elements and sheet-shaped ammonia borane, stack them in the order of sheet-shaped ammonia borane, sheet-shaped lanthanide metal element, sheet-shaped ammonia borane, sheet-shaped lanthanide metal element, sheet-shaped ammonia borane, and wrap them with tantalum foil to obtain packaged sample 6; the six-sided top press high temperature and high pressure synthesis block assembly as shown in Figure 1 As shown;
[0034] S2: loading the encapsulated sample 6 obtained in step S1 into a synthesis chamber of a high-temperature and high-pressure synthesis block of a six-sided top press, heating and pressurizing, and maintaining the temperature and pressure, and then cooling and releasing the pressure to obtain a lanthanide metal hydride;
[0035] Figure 2 This is the assembly diagram of the lanthanide metal element and NH3BH3 used in the experiment; the assembled sample 6 is obtained by stacking flake ammonia borane, flake lanthanide metal element, flake ammonia borane, flake lanthanide metal element, and flake ammonia borane in sequence and wrapping them with tantalum foil. The tantalum foil is used to prevent the sample 6 from being contaminated, seal the hydrogen source, and prevent hydrogen from overflowing.
[0036] The heating method is to generate Joule heating by electrifying the graphite, and the heating temperature is 800-1200°C.
[0037] Preferably, in step S1, the lanthanide metal element is one of elemental Yb, elemental Tb and elemental Ho.
[0038] Preferably, in step S2, the six-sided top press high temperature and high pressure synthetic block assembly diagram is as follows Figure 1 shown.
[0039] Preferably, in step S2, when the lanthanide metal single substance is single substance Yb or single substance Ho, the heating temperature is 800°C; when the lanthanide metal single substance is single substance Tb, the heating temperature is 1200°C.
[0040] Preferably, in step S2, the pressurization pressure is 4 GPa, and the heat preservation and pressure holding time is 60-90 minutes.
[0041] Preferably, in step S2, the equipment used for heating and pressurizing is a hinged six-sided press.
[0042] Preferably, in step S2, the chamber is heated in the following manner: the energized graphite column 3, graphite sheet 4 and graphite tube 8 are used to heat the packaged sample 6, and the energized conductive medium is the steel cap 1 and the molybdenum sheet 2.
[0043] Preferably, in step S2, the packaged sample 6 is wrapped with a boron nitride tube and a boron nitride sheet 7.
[0044] Preferably, in step S2, the cooling and depressurizing method is: after stopping the power supply for heating, the sample 6 is naturally cooled to room temperature, and then the pressure is relieved to normal pressure.
[0045] Preferably, in step S2, the pressurized pressure transmission medium is magnesium oxide 5, and magnesium oxide 5 plays a role in transmitting pressure.
[0046] The present invention also provides a lanthanide metal hydride, which is prepared by the above preparation method.
[0047] The following is a detailed description of the above-mentioned solution of the present invention in combination with specific data:
[0048] Example 1
[0049] S1: Cut the Yb single substance into sheets of the required size in a glove box, and stack them with NH3BH3 (ammonia borane) in the form of a layer of NH3BH3 and a layer of Yb single substance sheet, stacking five layers in total, and wrapping them with tantalum foil to obtain encapsulated sample 6;
[0050] S2: Load the assembled sample 6 into the synthesis chamber of the high temperature and high pressure synthesis block, such as Figure 1As shown, the obtained assembly block is placed in a hinged six-sided top press, the packaged sample 6 is wrapped by a boron nitride tube and a boron nitride sheet 7, and the magnesium oxide 5 is in contact with the boron nitride tube and the boron nitride sheet 7. The magnesium oxide 5 serves as a pressure transmission medium and can pressurize the packaged sample 6 during the pressurization process; the magnesium oxide 5 at both ends is in contact with the graphite tube 8, the graphite column 3, the molybdenum sheet 2 and the steel cap 1, and the current is conducted to the graphite column 3 and the graphite sheet 4 through the steel cap 1 and the molybdenum sheet 2, thereby playing a heating role;
[0051] In the encapsulated sample 6, a graphite tube 8 is used for heating, magnesium oxide 5 is used as a pressure transmission medium, a boron nitride tube and a boron nitride sheet 7 are used to wrap the sample 6 to prevent contamination of the sample 6, and a steel cap 1, a molybdenum sheet 2 and a graphite sheet 4 are used to conduct current. The synthesis pressure is 4 GPa, the synthesis temperature is 800-1200°C, the temperature is kept for 60 minutes and the pressure is kept for 90 minutes. After stopping heating, the sample 6 is naturally cooled to room temperature and then the pressure is released. The X-ray diffraction results of YbHx prepared under different temperature conditions are shown in Figure 3 , compared with the standard PDF card, see Figure 4 .
[0052] Example 2
[0053] S1: Cut Tb into sheets of required size in a glove box, and stack them with NH3BH3 (ammonia borane) in the form of one layer of NH3BH3 and one layer of Tb sheets, stacking five layers in total, and wrapping them with tantalum foil to obtain encapsulated sample 6;
[0054] S2: Load the packaged sample 6 into the synthesis chamber of the high-temperature and high-pressure synthesis block. The high-temperature and high-pressure assembly uses a graphite tube 8 for heating, magnesium oxide 5 as a pressure medium, and a boron nitride tube and a boron nitride sheet 7 to wrap the sample 6 to prevent contamination of the sample 6. The steel cap 1, the molybdenum sheet 2 and the graphite sheet 4 are used to conduct current. The synthesis pressure is 4GPa, the synthesis temperature is 800-1200℃, the temperature is kept for 60 minutes and the pressure is kept for 90 minutes. After stopping heating, the sample 6 is naturally cooled to room temperature and then the pressure is released. The X-ray diffraction results of TbHx prepared under different temperature conditions are shown in Figure 5 , compared with the standard PDF card, see Figure 6 .
[0055] Example 3
[0056] S1: Cut the Ho element into sheets of the required size in a glove box, and stack them with NH3BH3 (ammonia borane) in the form of one layer of NH3BH3 and one layer of Ho element, stacking five layers in total, and wrapping them with tantalum foil to obtain encapsulated sample 6;
[0057] S2: The encapsulated sample 6 is loaded into the synthesis chamber of the high-temperature and high-pressure synthesis block. The encapsulated sample 6 is heated by a graphite tube 8, magnesium oxide 5 is used as a pressure transmission medium, a boron nitride tube and a boron nitride sheet 7 are used to wrap the sample 6 to prevent contamination of the sample 6, and a steel cap 1, a molybdenum sheet 2 and a graphite sheet 4 are used to conduct current. The synthesis pressure is 4GPa, the synthesis temperature is 800-1200℃, the temperature is kept for 60 minutes and the pressure is kept for 90 minutes. After stopping the heating, the sample 6 is naturally cooled to room temperature and then the pressure is released. The X-ray diffraction results of HoHx prepared under different temperature conditions are shown in Figure 7 , compared with the standard PDF card, see Figure 8 .
[0058] The experiments involved in the above embodiments were completed in a 6mm experimental assembly on a domestic hinged six-sided top press.
[0059] In the above embodiment 1 Figure 4 The XRD pattern shows that under 4 GPa pressure, when the temperature reaches 800 °C, the raw material is completely transformed into a single YbH 2.5 In the above embodiment 2 Figure 6 The XRD pattern shows that: under a pressure of 4 GPa, when the temperature reaches 1200°C, lanthanide metal hydride TbH2 is synthesized. Figure 8 It can be seen that under a pressure of 4 GPa, when the temperature reaches 800°C, the raw material is completely transformed into a single HoH2.
[0060] It can be seen from Examples 1-3 that synthesis pressure and temperature are important factors affecting the synthesis of lanthanide metal hydrides. The present invention prepares lanthanide metal hydrides by encapsulating the above-mentioned raw materials and specifically controlling the synthesis pressure and temperature.
[0061] The above embodiments further illustrate that the present invention provides a method for preparing lanthanide metal hydrides with a short preparation cycle, mild conditions and low cost, which solves the difficulties in mass production of hydrides and the risk of hydrogen explosion in conventional preparation methods.
[0062] Although the patent disclosure is disclosed as above, the protection scope of the patent disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the patent disclosure, and these changes and modifications will fall within the protection scope of the present invention.
Claims
1. A method for preparing a lanthanide metal hydride, characterized in that: The following steps are involved: S1: cutting a lanthanide metal element and ammonia borane into sheets of the same size to obtain a plurality of sheet-like lanthanide metal elements and sheet-like ammonia borane, stacking them in the order of sheet-like ammonia borane, sheet-like lanthanide metal element, sheet-like ammonia borane, sheet-like lanthanide metal element, and sheet-like ammonia borane, and wrapping them with tantalum foil to obtain a packaged sample; S2: loading the packaged sample obtained in step S1 into a synthesis chamber of a six-sided top press, heating and pressurizing, and keeping the temperature and pressure, and then cooling and releasing the pressure to obtain a lanthanide metal hydride; In the step S1, the lanthanide metal element is one of elemental Yb, elemental Tb and elemental Ho; When the lanthanide metal single substance is single substance Yb or single substance Ho, the heating temperature is 800° C.; when the lanthanide metal single substance is single substance Tb, the heating temperature is 1200° C.; In step S2, the pressurization pressure is 4 GPa, and the heat preservation and pressure holding time is 60-90 minutes; The chamber is heated in the following manner: electrified graphite columns, graphite sheets and graphite tubes are used to heat the packaged samples; the electrified conductive media are steel caps and molybdenum sheets; and the packaged samples are wrapped with boron nitride tubes and boron nitride sheets.
2. The method for preparing lanthanide metal hydrides according to claim 1, characterized in that: Boron nitride is also arranged between the packaged sample and the graphite tube.
3. The method for preparing lanthanide metal hydrides according to claim 1, characterized in that: In step S2, the cooling and depressurizing method is: after the power heating is stopped, the sample is naturally cooled to room temperature and then depressurized to normal pressure.
4. The method for preparing lanthanide metal hydrides according to claim 1, characterized in that: The pressurized pressure transmission medium is magnesium oxide.
5. A lanthanide metal hydride, characterized in that: The lanthanide metal hydride is prepared by the preparation method according to any one of claims 1 to 4.