LuNxHy film and preparation method thereof
By using a two-step method to prepare LuNxHy thin films, the problem of finely controlling the nitrogen content in nitrogen-doped rare earth hydrides has been solved, enabling the preparation of stable single-crystal or polycrystalline Lu-HN thin films at room temperature and pressure, which is suitable for large-scale production.
Patent Information
- Application Number
- CN202411534424.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-31
- Publication Date
- 2025-11-28
AI Technical Summary
Existing technologies for nitrogen-doped rare earth hydrides suffer from the problem of difficulty in precisely controlling nitrogen content, and the preparation of single-crystal thin films is inadequate. It is difficult to prepare single-crystal or polycrystalline single-crystal thin films due to internal stress issues, and the preparation methods for polycrystalline single-crystal thin films are difficult to implement.
A two-step method was used to prepare LuNxHy thin films. First, LuNx thin films were deposited on a substrate by reactive sputtering, and then heat treatment was performed in a hydrogen-containing atmosphere to prepare single-crystal or polycrystalline Lu-HN thin films with finely controllable nitrogen content.
It has been achieved that LuNxHy thin films with stable structure and properties can be prepared at room temperature and pressure, and the nitrogen doping amount can be precisely controlled. It is suitable for large-scale production and can prepare large-size single crystal or polycrystalline thin films, solving the problem that single crystal thin films are difficult to prepare in the prior art.
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Abstract
Description
Technical Field
[0001] This disclosure relates to the field of thin film preparation technology, and in particular to a LuN... x H y Thin films and their preparation methods. Background Technology
[0002] Theoretical studies suggest that metallic hydrogen may be a room-temperature superconductor, but obtaining metallic hydrogen requires extremely high pressures. Hydrogen-rich compounds hold promise for reducing the pressure required for hydrogen metallization through "chemical pre-compression." Binary hydrides such as H3S, YH9, and LaH2S are examples. 10 High-pressure, high-temperature superconductivity has been experimentally demonstrated in some rare earth hydrides. Theoretical predictions indicate a superconducting transition temperature of 273 K at 100 GPa for LuH6, while experiments have shown a superconducting transition temperature of 12.4 K at 122 GPa for LuH3. Recent theoretical studies have shown that doping the La-H system with B and N can increase the superconducting transition temperature, making nitrogen-doped rare earth hydrides a hot research topic.
[0003] Current research on nitrogen-doped rare-earth hydrides faces the challenge of precisely controlling the nitrogen content. For example, Dias et al. synthesized polycrystalline Lu-HN films by reacting lutetium (Lu) foil with a mixture of hydrogen and nitrogen under high pressure; the reaction product contained LuN. 1-δ H ε and LuH 3-δ N ε However, this research suffers from problems such as non-single products, uneven nitrogen content, and difficulty in precise control. On the other hand, it is necessary to introduce single-crystal thin films into rare-earth hydride research, as the internal stress of single-crystal thin films may help to improve the superconducting transition temperature and optimize the pressure.
[0004] Therefore, it is necessary to provide a new preparation method to prepare uniform single-crystal or polycrystalline Lu-HN thin films with finely controllable nitrogen content. Summary of the Invention
[0005] This patent provides a LuN x H y Thin films and their preparation methods are proposed to at least solve the above-mentioned technical problems existing in the prior art.
[0006] According to a first aspect of this disclosure, a LuN is provided. x H y The method for preparing a thin film includes the following steps:
[0007] Using Lu metal as the target material and an argon-nitrogen mixture as the reactive gas, LuN is deposited on the substrate via reactive sputtering. x Thin film; LuN x The thin film is heat-treated in an atmosphere containing hydrogen to obtain the LuN.x H y film;
[0008] The LuN x H y The thin film is a monocrystalline thin film or a polycrystalline thin film; in the LuN x H y In the thin film, 0 < x < 1, y > 1.
[0009] Specifically, this disclosure is the first to employ the above two-step method, firstly using reactive sputtering to prepare stable LuN. x Thin films allow for precise, uniform, and repeatable control of N doping levels; then, LuN... x Hydrogenation of the thin film yielded a Lu-HN thin film. This method can prepare both polycrystalline and single-crystal Lu-HN thin films, representing a significant improvement over existing technologies (which can only prepare polycrystalline Lu-HN thin films).
[0010] In a preferred embodiment, the LuN x H y The thin film is a single-crystal thin film.
[0011] In one embodiment, the volume fraction of nitrogen in the argon-nitrogen mixture is 0.1% to 95%.
[0012] In a preferred embodiment, the nitrogen gas accounts for 3-15% of the volume in the argon-nitrogen mixture.
[0013] In one embodiment, the substrate is selected from at least one of single-crystal magnesium oxide, single-crystal aluminum oxide, single-crystal strontium titanate, single-crystal magnesium aluminate, single-crystal yttrium-doped zirconium oxide, silicon wafer, glass, and mica.
[0014] In one possible implementation, when the prepared LuN x H y When the thin film is a single-crystal thin film, the substrate is selected from at least one of single-crystal magnesium oxide, single-crystal aluminum oxide, single-crystal strontium titanate, single-crystal magnesium aluminate, single-crystal yttrium-doped zirconium oxide, and mica.
[0015] In one embodiment, before performing the reactive sputtering, the substrate is further cleaned by ultrasonic cleaning using acetone and alcohol as solvents, followed by drying with nitrogen gas after 15-20 minutes.
[0016] In one possible embodiment, the vacuum pressure of the reactive sputtering is <1×10⁻⁶. -6 Torr.
[0017] In one embodiment, during the reactive sputtering, the pressure of the reactive gas is 10–50 mTorr, the temperature of the substrate is 25–500 °C, and the sputtering power is 40–120 W.
[0018] In one possible implementation, the LuN x The thin film can be a monocrystalline thin film or a polycrystalline thin film.
[0019] In a preferred embodiment, the LuN x The thin film is a single-crystal thin film.
[0020] In one embodiment, the hydrogen-containing atmosphere is an argon-hydrogen mixture, wherein the volume fraction of hydrogen is 1-10%.
[0021] In a preferred embodiment, the hydrogen-containing atmosphere is an argon-hydrogen mixture, wherein the hydrogen accounts for 8% of the volume.
[0022] In one embodiment, the heat treatment temperature is 200–400°C and the time is 1–6 hours.
[0023] In a preferred embodiment, the heat treatment is performed at a temperature of 280°C for 4 hours.
[0024] According to a second aspect of this disclosure, LuN prepared according to the above-described preparation method is provided. x H y Thin film; in the LuN x H y In the thin film, 0 < x < 1, y > 1; the LuN x H y The thin film can be a monocrystalline thin film or a polycrystalline thin film.
[0025] According to one possible implementation of this disclosure, at least the following beneficial effects are achieved:
[0026] This disclosure describes a two-step method for preparing structurally and property-stable LuN. x H y This method for preparing thin films is simple, low-cost, and suitable for large-scale production. It requires no high pressure, allows for precise control of film size, and enables the fabrication of large-size Lu-HN thin films. LuN films prepared using this method are described below. x H y The thin film can exist stably at room temperature and pressure, and can be either single-crystal or polycrystalline, solving the problem that existing technologies cannot prepare single-crystal thin films. Specifically, it is used to prepare LuN... x In thin film fabrication, the nitrogen doping level can be precisely, uniformly, and repeatably controlled, and the prepared LuN... x The thin film is stable at room temperature and pressure.
[0027] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description
[0028] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which:
[0029] In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.
[0030] Figure 1 The LuN shown in Embodiment 1 of this disclosure is illustrated. x H y A schematic diagram of the cross-sectional structure of a single-crystal thin film;
[0031] Figure 2 The LuN shown in Embodiment 1 of this disclosure is illustrated. x X-ray photoelectron spectrum of single-crystal thin films;
[0032] Figure 3 The LuN shown in Embodiment 1 of this disclosure is illustrated. x H y Time-of-flight-secondary ion mass spectra of single-crystal thin films;
[0033] Figure 4 The LuN shown in Embodiment 1 of this disclosure is illustrated. x H y X-ray diffraction pattern of a single-crystal thin film.
[0034] Figure label:
[0035] 1-Substrate; 2-LuN x H y Single-crystal thin films. Detailed Implementation
[0036] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.
[0037] Example 1
[0038] This embodiment prepares a LuN xH y A single-crystal thin film (0 < x < 1, y > 1) was prepared using single-crystal MgO (111) as the substrate, an argon-nitrogen mixed gas (nitrogen volume fraction of 2%) as the reaction gas, and a Lu metal target. The specific process is as follows:
[0039] (1) Using a 5*5*0.5mm single crystal MgO(111) as a substrate, the substrate was first ultrasonically cleaned for 15 minutes with analytical grade acetone and alcohol as solvents, and then dried with nitrogen.
[0040] (2) Load the cleaned substrate onto the sample stage of the sputtering chamber, and use a vacuum pump to obtain a vacuum level of 1×10⁻⁶. -6 Torr below.
[0041] (3) Continuously introduce an argon-nitrogen mixture into the sputtering chamber as the reactant gas, maintaining the gas pressure at 20 mTorr, and heat the substrate to 300°C. Turn on the RF power supply, set the RF power to 80W, and perform pre-sputtering. After 30 minutes of pre-sputtering, open the substrate baffle, and LuN... x The single-crystal thin film is gradually deposited onto the substrate. After 1 hour of sputtering, the substrate baffle and RF power supply are turned off, thus completing the LuN process. x Preparation of single-crystal thin films.
[0042] (4) LuN x A single-crystal thin film was placed in a tube furnace, and an argon-hydrogen mixture (8% hydrogen by volume) was introduced for 1 hour. The temperature of the tube furnace was then raised to 280°C and maintained for 4 hours, with the argon-hydrogen mixture continuously introduced. After natural cooling to room temperature, LuN was obtained. x H y Single-crystal thin films.
[0043] The LuN prepared above x H y The cross-sectional structure of a single-crystal thin film is as follows: Figure 1 As shown, the thin film includes substrate 1 and LuN. x H y Single-crystal thin film 2. LuN x X-ray photoelectron spectrum of single-crystal thin film as shown in Figure Figure 2 As shown, it can be seen that LuN x The single-crystal thin film contains nitrogen (N). Regarding this LuN... x H y The single-crystal thin film was subjected to compositional analysis, and its time-of-flight-secondary ion mass spectrum is shown below. Figure 3 As shown, Figure 3 The display shows that LuN x H y The single-crystal thin film contains Lu, H, and N elements. High-resolution X-ray diffraction was also used to test the LuN.x H y Crystal structure of single-crystal thin films (see Figure 4 The results showed that the film had a cubic structure.
[0044] Example 2
[0045] This embodiment prepares a LuN x H y A single-crystal thin film (0 < x < 1, y > 1) was prepared using single-crystal MgO (111) as the substrate, an argon-nitrogen mixed gas (nitrogen volume fraction of 6%) as the reaction gas, and a Lu metal target. The specific process is as follows:
[0046] (1) Using a 5*5*0.5mm single crystal MgO(111) as a substrate, the substrate was first ultrasonically cleaned for 15 minutes with analytical grade acetone and alcohol as solvents, and then dried with nitrogen.
[0047] (2) Load the cleaned substrate onto the sample stage of the sputtering chamber, and use a vacuum pump to obtain a vacuum level of 1×10⁻⁶. -6 Torr below.
[0048] (3) Continuously introduce an argon-nitrogen mixture into the sputtering chamber as the reactant gas, maintaining the gas pressure at 20 mTorr, and heat the substrate to 300°C. Turn on the RF power supply, set the RF power to 80W, and perform pre-sputtering. After 30 minutes of pre-sputtering, open the substrate baffle, and LuN... x The single-crystal thin film is gradually deposited onto the substrate. After 1 hour of sputtering, the substrate baffle and RF power supply are turned off, thus completing the LuN process. x Preparation of single-crystal thin films.
[0049] (4) LuN x A single-crystal thin film was placed in a tube furnace, and an argon-hydrogen mixture (8% hydrogen by volume) was introduced for 1 hour. The temperature of the tube furnace was then raised to 280°C and maintained for 4 hours, with the argon-hydrogen mixture continuously introduced. After natural cooling to room temperature, LuN was obtained. x H y Single-crystal thin films.
[0050] For this LuN x H y Compositional analysis of the single-crystal thin film using time-of-flight secondary ion mass spectrometry revealed the presence of Lu, H, and N elements. High-resolution X-ray diffraction was also used to analyze the LuN composition. x H y The crystal structure of the thin film proves that the thin film has a cubic structure.
[0051] Example 3
[0052] This embodiment prepares a LuN x H y A polycrystalline thin film (0 < x < 1, y > 1) is prepared using glass as the substrate, an argon-nitrogen mixed gas (nitrogen volume fraction of 2%) as the reactant gas, and a Lu metal target. The specific process is as follows:
[0053] (1) Use 5*5*0.5mm glass as substrate. First, use analytical grade acetone and alcohol as solvents to ultrasonically clean the substrate for 15 minutes, and then blow it dry with nitrogen.
[0054] (2) Load the cleaned substrate onto the sample stage of the sputtering chamber, and use a vacuum pump to obtain a vacuum level of 1×10⁻⁶. -6 Torr below.
[0055] (3) Continuously introduce an argon-nitrogen mixture into the sputtering chamber as the reactant gas, maintaining the gas pressure at 20 mTorr, and keep the substrate at room temperature. Turn on the RF power supply, set the RF power to 80W, and perform pre-sputtering. After 30 minutes of pre-sputtering, open the substrate baffle, and LuN... x The polycrystalline thin film gradually deposited onto the substrate. After 1 hour of sputtering, the substrate baffle and RF power supply were turned off, thus completing the LuN process. x Preparation of polycrystalline thin films.
[0056] (4) LuN x A polycrystalline thin film was placed in a tube furnace, and an argon-hydrogen mixture (8% hydrogen by volume) was introduced for 1 hour. The temperature of the tube furnace was then raised to 280°C and maintained for 4 hours, with the argon-hydrogen mixture continuously introduced. After natural cooling to room temperature, LuN was obtained. x H y Polycrystalline film.
[0057] For this LuN x H y Compositional analysis of the polycrystalline thin film using time-of-flight secondary ion mass spectrometry revealed the presence of Lu, H, and N elements. High-resolution X-ray diffraction was also used to analyze the LuN composition. x H y The crystal structure of the polycrystalline thin film proves that the film has a cubic structure.
[0058] Comparative Example 1
[0059] This comparative example prepared a LuN x H y The difference between this comparative example and Example 1 is that pure nitrogen gas was used as the reactant gas. The rest of the process is the same as in Example 1.
[0060] The results showed that the LuN prepared in this comparative example x H yIn the thin film, 0 < x < 1, y < 1, which is different from the range of y values in the thin film prepared in Example 1.
[0061] Comparative Example 2
[0062] This comparative example prepared a LuN x H y The difference between this comparative example and Example 1 is that the temperature of the tube furnace was kept at room temperature throughout the heat treatment process, without any heating. The rest of the process was the same as in Example 1.
[0063] The results showed that the LuN prepared in this comparative example x H y In the thin film, 0 < x < 1, y < 1, which is different from the range of y values in the thin film prepared in Example 1.
[0064] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this disclosure can be achieved, and this is not limited herein.
[0065] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.
[0066] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.
Claims
1. A LuN x H y A method for preparing a thin film, characterized in that, Includes the following steps: Using Lu metal as the target material and an argon-nitrogen mixture as the reactive gas, LuN is deposited on the substrate via reactive sputtering. x Thin film; LuN x The thin film is heat-treated in an atmosphere containing hydrogen to obtain the LuN. x H y film; The LuN x H y The thin film is a monocrystalline thin film or a polycrystalline thin film; in the LuN x H y In the thin film, 0 < x < 1, y > 1.
2. The preparation method according to claim 1, characterized in that, The LuN x H y The thin film is a single-crystal thin film.
3. The preparation method according to claim 1, characterized in that, In the argon-nitrogen mixed gas, nitrogen accounts for 0.1% to 95% of the volume.
4. The preparation method according to claim 1, characterized in that, The substrate is selected from at least one of the following: single-crystal magnesium oxide, single-crystal aluminum oxide, single-crystal strontium titanate, single-crystal magnesium aluminate, single-crystal yttrium-doped zirconium oxide, silicon wafer, glass, and mica.
5. The preparation method according to claim 1, characterized in that, The vacuum pressure of the reactive sputtering is <1×10⁻⁶. - 6 Torr.
6. The preparation method according to claim 1, characterized in that, In the reactive sputtering, the temperature of the substrate is 25–500°C.
7. The preparation method according to claim 1, characterized in that, The LuN x The thin film can be a monocrystalline thin film or a polycrystalline thin film.
8. The preparation method according to claim 1, characterized in that, The atmosphere containing hydrogen is an argon-hydrogen mixture, wherein the volume fraction of hydrogen is 1-10%.
9. The preparation method according to claim 1, characterized in that, The heat treatment is performed at a temperature of 200–400°C for a duration of 1–6 hours.
10. LuN prepared by the method according to any one of claims 1 to 9 x H y The thin film is characterized by, In the LuN x H y In the thin film, 0 < x < 1, y > 1; the LuN x H y The thin film can be a monocrystalline thin film or a polycrystalline thin film.