A biaxially textured nickel oxide buffer layer, its preparation method and use

Abstract

The application provides a biaxial texture nickel oxide buffer layer and a preparation method and application thereof, and relates to the technical field of coated conductor preparation.The preparation method of the biaxial texture nickel oxide buffer layer provided by the application comprises the following steps: performing recrystallization annealing treatment on a nickel alloy in a reducing atmosphere to obtain a biaxial texture nickel alloy; and performing oxidation treatment on the biaxial texture nickel alloy in an oxidizing atmosphere to obtain the biaxial texture nickel oxide buffer layer.The biaxial texture nickel oxide buffer layer is prepared by using a controllable oxidation recrystallization texture method, the prepared biaxial texture nickel oxide buffer layer has good c-axis orientation, low surface roughness, and good in-plane and out-of-plane growth texture.The preparation process is simple, the operation control is simple, the cost is low, the application is environment-friendly, and the application is suitable for large-scale application.

Description

Technical Field

[0001] This invention relates to the field of coated conductor preparation technology, specifically to a biaxially textured nickel oxide buffer layer, its preparation method, and its application. Background Technology

[0002] Second-generation high-temperature superconducting tapes (i.e., yttrium-based coated conductors) have a wide range of applications. Compared with first-generation bismuth-based superconducting tapes, they have better high magnetic field current-carrying performance. Therefore, developing practical high-performance yttrium-based (such as YBCO) superconducting thin films has become a common goal for researchers around the world. Since directly depositing YBCO thin films on NiW substrates presents lattice mismatch problems and can also induce oxidation of the metal substrate and interdiffusion between elements, a buffer layer must be inserted between the two to transfer texture and block interdiffusion. The quality of the buffer layer greatly affects the performance of the subsequently deposited superconducting layer.

[0003] Currently, the main methods for preparing buffer layers are divided into vacuum physical methods and non-vacuum chemical methods. Although the quality of buffer layer films prepared by vacuum physical methods is relatively good, the equipment used in the preparation process is expensive, resulting in high costs and hindering the large-scale, high-efficiency deposition of buffer layers. While non-vacuum chemical methods can prepare buffer layers on a large scale, once the number of layers is large, they are prone to cracking at high temperatures, increasing the difficulty of subsequent coating conductor preparation. Summary of the Invention

[0004] The purpose of this invention is to provide a biaxially textured nickel oxide buffer layer, its preparation method, and its application. This invention utilizes a controlled oxidation-recrystallization texture method to prepare the nickel oxide buffer layer. The prepared nickel oxide buffer layer has good c-axis orientation, low surface roughness, and good in-plane and out-of-plane growth texture. Furthermore, its preparation process is simple, easy to operate and control, low in cost, environmentally friendly, and suitable for large-scale applications.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing a biaxially textured nickel oxide buffer layer, comprising the following steps:

[0007] A biaxially textured nickel alloy was obtained by recrystallizing and annealing the nickel alloy in a reducing atmosphere.

[0008] The biaxially textured nickel alloy was oxidized in an oxidizing atmosphere to obtain a biaxially textured nickel oxide buffer layer.

[0009] Preferably, the nickel alloy further includes a surface cleaning treatment before recrystallization annealing.

[0010] Preferably, the reducing atmosphere is an atmosphere containing hydrogen.

[0011] Preferably, the volume fraction of hydrogen in the reducing atmosphere is 3-5%.

[0012] Preferably, the recrystallization annealing treatment is performed at a temperature of 850–950°C for a holding time of 25–35 minutes.

[0013] Preferably, the oxidizing atmosphere is an atmosphere containing oxygen.

[0014] Preferably, the volume fraction of oxygen in the oxidizing atmosphere is 0.3% to 2%.

[0015] Preferably, the oxidation treatment temperature is 900–1000°C, and the holding time is 3–9 min.

[0016] The present invention provides a biaxially textured nickel oxide buffer layer prepared by the preparation method described in the above technical solution.

[0017] This invention provides the application of the biaxially textured nickel oxide buffer layer described above in the deposition of superconducting layers.

[0018] This invention provides a method for preparing a biaxially textured nickel oxide buffer layer. First, a nickel alloy is recrystallized and annealed in a reducing atmosphere to obtain a biaxially textured nickel alloy. This solves the problem of randomly oriented layers appearing on the surface of nickel alloys after being exposed to air for a certain period. This method not only removes the non-oriented NiO on the nickel alloy surface but also strengthens the texture of the nickel alloy itself, which is beneficial for subsequent recrystallization. Next, the biaxially textured nickel alloy is oxidized in an oxidizing atmosphere to obtain biaxially textured NiO, which serves as a buffer layer for the superconducting layer. The preparation method provided by this invention not only avoids the problem of excessive oxidation of the nickel alloy but also allows the oxidation products of the substrate to be used directly as a buffer layer without the need for additional chemical reagents. It is environmentally friendly, simple, and low-cost, making it suitable for large-scale application. Furthermore, this method effectively solves the problem of spontaneous and non-directional oxidation of the nickel alloy substrate, protecting the substrate while also transferring the texture. Attached Figure Description

[0019] Figure 1 The X-ray diffraction pattern of the NiO buffer layer prepared in Example 1 of this invention;

[0020] Figure 2 The laser confocal three-dimensional microstructure of the NiO buffer layer prepared in Example 1 of this invention;

[0021] Figure 3 The X-ray diffraction pattern of the NiO buffer layer prepared in Example 2 of this invention;

[0022] Figure 4 The laser confocal three-dimensional microstructure of the NiO buffer layer prepared in Example 2 of this invention;

[0023] Figure 5 The X-ray diffraction ω-scan pattern of the NiO buffer layer prepared in Example 3 of this invention;

[0024] Figure 6 The X-ray diffraction ψ-scan pattern of the NiO buffer layer prepared in Example 3 of this invention;

[0025] Figure 7 This is an EBSD grain distribution diagram of the NiO buffer layer prepared in Example 3 of the present invention;

[0026] Figure 8 This is the EBSD pole diagram of the NiO buffer layer prepared in Example 3 of the present invention. Detailed Implementation

[0027] This invention provides a method for preparing a biaxially textured nickel oxide buffer layer, comprising the following steps:

[0028] A biaxially textured nickel alloy was obtained by recrystallizing and annealing the nickel alloy in a reducing atmosphere.

[0029] The biaxially textured nickel alloy was oxidized in an oxidizing atmosphere to obtain a biaxially textured nickel oxide buffer layer.

[0030] This invention involves recrystallizing and annealing a nickel alloy in a reducing atmosphere to obtain a biaxially textured nickel alloy. In this invention, the atomic percentage of nickel in the nickel alloy is preferably 90–99 at.%, more preferably 95 at.%. In this invention, the nickel alloy is preferably a NiW alloy, specifically preferably a NiW base material.

[0031] In this invention, the nickel alloy preferably undergoes a surface cleaning treatment before recrystallization annealing. This surface cleaning treatment preferably includes sequential acetone cleaning and ethanol cleaning. This invention removes organic matter and impurities from the nickel alloy surface through surface cleaning, resulting in a smooth and flat surface with a cleaner finish. This avoids irregular protrusions during subsequent growth, ensures the continuity of the baseband, and facilitates the continuity of subsequent superconducting layer growth.

[0032] In this invention, the reducing atmosphere is preferably an atmosphere containing hydrogen. The volume fraction of hydrogen in the reducing atmosphere is preferably 3-5%, more preferably 4%. The reducing atmosphere preferably also includes nitrogen or an inert gas, more preferably argon. By controlling the hydrogen content within the above range, this invention avoids the risk of hydrogen combustion and explosion at high temperatures.

[0033] In this invention, the temperature of the recrystallization annealing treatment is preferably 850–950°C, more preferably 900°C; the holding time is preferably 25–35 min, more preferably 30 min. In this invention, the heating rate from room temperature to the recrystallization annealing temperature is preferably 5–100°C / min, more preferably 10–20°C / min.

[0034] In this invention, the recrystallization annealing treatment is preferably carried out in a tube furnace.

[0035] The present invention utilizes the recrystallization annealing treatment to reduce and recrystallize the non-c-axis oriented NiO on the surface of the nickel alloy to form a textured nickel alloy.

[0036] After obtaining the biaxially textured nickel alloy, the present invention oxidizes the biaxially textured nickel alloy in an oxidizing atmosphere to obtain a biaxially textured nickel oxide buffer layer. In the present invention, the oxidizing atmosphere is preferably an atmosphere containing oxygen. In the present invention, the volume fraction of oxygen in the oxidizing atmosphere is preferably 0.3% to 2%. In the present invention, the oxidizing atmosphere is preferably a mixed atmosphere of oxygen and nitrogen or a mixed atmosphere of oxygen and an inert gas. In the present invention, the volume ratio of oxygen to nitrogen in the mixed atmosphere of oxygen and nitrogen is preferably 1:50 to 300, more preferably 1:200 to 250; the volume ratio of oxygen to inert gas in the mixed atmosphere of oxygen and inert gas is preferably 1:50 to 300, more preferably 1:200 to 250. By controlling the ratio of oxygen and nitrogen within the above ranges, the present invention can generate NiO with good c-axis orientation and no impurity phases, ensuring its good texture.

[0037] In this invention, the oxidation treatment temperature is preferably 900–1000°C, more preferably 950–980°C; the holding time is preferably 3–9 min, more preferably 5–6 min. By controlling the oxidation treatment temperature within the above range, this invention ensures that the film has good orientation and a high degree of biaxial texture. By controlling the holding time of the oxidation treatment to 3–9 min, this invention enables the film to have good surface roughness and a relatively smooth surface, which meets the conditions for subsequent deposition of a superconducting layer.

[0038] In this invention, the oxidation treatment is preferably carried out in a tubular atmosphere furnace with a movable furnace chamber. In a specific embodiment of this invention, the biaxially textured nickel alloy is placed in a tubular furnace with a movable furnace chamber, and the furnace chamber is moved to one side. At the same time, an oxidizing gas is introduced into the furnace tube. Once the furnace chamber temperature rises to the temperature of the oxidation treatment, the furnace chamber is directly moved to the biaxially textured nickel alloy, so that the biaxially textured nickel alloy is rapidly heated to the temperature of the oxidation treatment and held at that temperature.

[0039] Preferably, the present invention involves furnace cooling to room temperature after the oxidation treatment to obtain a biaxially textured nickel oxide buffer layer. In this invention, the furnace cooling is preferably carried out in a nitrogen atmosphere.

[0040] The nickel oxide buffer layer prepared by this invention has good c-axis orientation and good in-plane and out-of-plane texture properties, and its surface is relatively smooth. This method can effectively avoid the problem of oxide layer peeling caused by excessive oxidation of Ni substrate, and it does not require other chemicals, making it environmentally friendly. The process is simple, easy to control, has a short preparation time, saves energy, is easy to implement, and has low cost, making it suitable for large-scale industrial production.

[0041] This invention provides a biaxially textured nickel oxide buffer layer prepared by the preparation method described above. In this invention, the thickness of the biaxially textured nickel oxide buffer layer is preferably 50–500 nm, more preferably 100–200 nm.

[0042] The present invention provides the application of the biaxial textured nickel oxide buffer layer described above in the deposition of superconducting layers, preferably in the deposition of yttrium-based coated conductors, specifically in the deposition of YBCO superconducting thin films.

[0043] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0044] Example 1

[0045] Surface cleaning treatment of NiW baseband: Cut the NiW baseband (chemical composition is Ni-5at.%W alloy) into 10mm×10mm pieces, flatten it with a clean glass plate, clean the cut baseband with acetone, and then continue to clean the baseband with anhydrous ethanol.

[0046] Recrystallization annealing treatment of NiW substrate: The cut and cleaned NiW substrate is placed in a tube furnace and heated to 900℃ at a heating rate of 10℃ / min under an argon atmosphere containing 4% volH2. The substrate is then recrystallized and annealed at 900℃ for 30 min to obtain the pretreated NiW substrate.

[0047] Self-oxidation treatment of NiW substrate: The pretreated NiW substrate was placed in a tube furnace with a movable furnace chamber, and the furnace chamber was moved to one side. The furnace temperature was raised to 950°C. During the heating process, the O2 to N2 atmosphere ratio in the tube furnace was adjusted using a gas proportioner to control the O2 to N2 volume ratio at 1:200. After adjustment, the gas flow was allowed to continue for 35 minutes to ensure stable gas flow in the furnace. When the furnace temperature reached 950°C, the furnace chamber was moved to the sample location to begin the oxidation treatment, which lasted for 6 minutes. The furnace chamber was then removed, the oxygen supply was turned off, and the nitrogen flow rate was increased. After cooling to room temperature with the furnace, the sample was taken to obtain a biaxially textured nickel oxide buffer layer.

[0048] Example 2

[0049] Surface cleaning treatment of NiW baseband: Cut the NiW baseband (chemical composition is Ni-5at.%W alloy) into 10mm×10mm pieces, flatten it with a clean glass plate, clean the cut baseband with acetone, and then continue to clean the baseband with anhydrous ethanol.

[0050] Recrystallization annealing treatment of NiW substrate: The cut and cleaned NiW substrate is placed in a tube furnace and heated to 900℃ at a heating rate of 15℃ / min under an argon atmosphere containing 4% volH2. The substrate is then recrystallized and annealed at 900℃ for 30 min to obtain the pretreated NiW substrate.

[0051] Self-oxidation treatment of NiW substrate: The pretreated NiW substrate was placed in a tube furnace with a movable furnace chamber, and the furnace chamber was moved to one side. The furnace temperature was raised to 980°C. During the heating process, the O2 to N2 atmosphere ratio in the tube furnace was adjusted using a gas proportioner to control the O2 to N2 volume ratio at 1:250. After adjustment, the gas flow was allowed to continue for 40 minutes to ensure stable gas flow in the furnace. When the furnace temperature reached 980°C, the furnace chamber was moved to the sample location to begin the oxidation treatment, which lasted for 5 minutes. Then, the furnace chamber was removed, the oxygen supply was turned off, and the nitrogen flow rate was increased. After cooling to room temperature with the furnace, the sample was taken to obtain a biaxial textured nickel oxide buffer layer.

[0052] Example 3

[0053] Surface cleaning treatment of NiW baseband: Cut the NiW baseband (chemical composition is Ni-5at.%W alloy) into 10mm×10mm pieces, flatten it with a clean glass plate, clean the cut baseband with acetone, and then continue to clean the baseband with anhydrous ethanol.

[0054] Recrystallization annealing treatment of NiW substrate: The cut and cleaned NiW substrate is placed in a tube furnace and heated to 900℃ at a heating rate of 20℃ / min under an argon atmosphere containing 4% volH2. The substrate is then recrystallized and annealed at 900℃ for 30 min to obtain the pretreated NiW substrate.

[0055] Self-oxidation treatment of NiW substrate: The pretreated NiW substrate was placed in a tube furnace with a movable furnace chamber, and the furnace chamber was moved to one side. The furnace temperature was raised to 950°C. During the heating process, the O2 to N2 atmosphere ratio in the tube furnace was adjusted using a gas proportioner to control the O2 to N2 volume ratio at 1:250. After adjustment, the gas flow was allowed to continue for 50 minutes to ensure stable gas flow in the furnace. When the furnace temperature reached 950°C, the furnace chamber was moved to the sample location to begin the oxidation treatment, which lasted for 5 minutes. Then, the furnace chamber was moved away, the oxygen supply was turned off, and the nitrogen flow rate was increased. After cooling to room temperature with the furnace, the sample was taken to obtain a biaxial textured nickel oxide buffer layer.

[0056] Test case

[0057] Figure 1 The X-ray diffraction pattern of the NiO buffer layer prepared in Example 1 of this invention is shown below. Figure 1 It can be seen that the NiO buffer layer film prepared in Example 1 shows a strong (200) preferred growth orientation in its internal grains.

[0058] Figure 2 The laser confocal three-dimensional microstructure of the NiO buffer layer prepared in Example 1 of this invention is shown below. Figure 2 It can be seen that the surface of the NiO buffer layer film prepared in Example 1 is relatively flat and dense.

[0059] Figure 3 The X-ray diffraction pattern of the NiO buffer layer prepared in Example 2 of this invention is shown below. Figure 3 It can be seen that the NiO buffer layer film prepared in Example 2 shows a strong (200) preferred growth orientation in its internal grains.

[0060] Figure 4 The laser confocal three-dimensional microstructure of the NiO buffer layer prepared in Example 2 of this invention is shown below. Figure 4 It can be seen that the surface of the NiO buffer layer film prepared in Example 2 is relatively flat and dense.

[0061] Figure 5 The X-ray diffraction ω-scan pattern of the NiO buffer layer prepared in Example 3 of this invention is shown below. Figure 5 It can be seen that the NiO buffer layer film prepared in Example 3 has a good out-of-plane growth texture.

[0062] Figure 6 The X-ray diffraction ψ-scan pattern of the NiO buffer layer prepared in Example 3 of this invention is shown below. Figure 6 It can be seen that the NiO buffer layer film prepared in Example 3 has a good in-plane growth texture.

[0063] Figure 7 This is an EBSD grain distribution diagram of the NiO buffer layer prepared in Example 3 of the present invention. Figure 7 It can be seen that the NiO buffer layer film prepared in Example 3 has uniform grain size on its surface and inherits the biaxial texture of the NiW substrate well.

[0064] Figure 8 The EBSD pole figure of the NiO buffer layer prepared in Example 3 of this invention is shown below. Figure 8 It can be seen that the NiO buffer layer film prepared in Example 3 has a strong (100) preferred growth orientation of the internal grains, which is consistent with the XRD test results.

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a biaxially textured nickel oxide buffer layer, comprising the following steps: recrystallization annealing a nickel alloy in a reducing atmosphere to obtain a biaxially textured nickel alloy; and oxidizing the biaxially textured nickel alloy in an oxidizing atmosphere to obtain a biaxially textured nickel oxide buffer layer; wherein the recrystallization annealing is performed at a temperature of 850-950 ℃ for 25-35 min; the oxidizing atmosphere contains 0.3-2% oxygen; and the oxidizing is performed at a temperature of 900-1000 ℃ for 3-9 min. 2.The method of claim 1, wherein the nickel alloy is further subjected to a surface cleaning treatment before the recrystallization annealing. 3.The method of claim 1 or 2, wherein the reducing atmosphere contains 3-5% hydrogen. 4.The method of claim 1, wherein the reducing atmosphere is an atmosphere containing hydrogen. 5.A biaxially textured nickel oxide buffer layer prepared by the method of any one of claims 1-4. 6.Use of the biaxially textured nickel oxide buffer layer of claim 5 in depositing a superconducting layer.

2. The production method according to claim 1, characterized by, ​ 3. The preparation method according to claim 1, characterized in that, ​ 4. The production method according to claim 3, characterized by, ​ ​ ​

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