CN106242553A - A kind of preparation method of high-temperature superconductor REBCO thin film - Google Patents

Abstract

The present invention provides a kind of preparation method of high-temperature superconducting REBCO thin film, and this method comprises the following steps: 1, according to the atomic ratio of RE: Ba: Cu=1: 1.75: 3 prepares the fluorine-free precursor solution; 2, according to RE: Ba : Cu=1: (1.5～2): 3 atomic ratio prepares the fluorine-containing precursor liquid; Three, adopt the spin coating method to uniformly coat the described fluorine-free precursor liquid on the LaAlO ₃ substrate, obtain the fluorine-free precursor liquid after heat treatment Single-layer precursor film; 4. Use the spin coating method to uniformly coat the fluorine-containing precursor solution on the fluorine-free single-layer precursor film, and obtain a fluorine-free/fluorine-containing double-layer precursor film after heat treatment; 5. The fluorine-free/containing The REBCO superconducting thin film was obtained after the fluorine double-layer precursor film was heat-treated. The preparation method of the invention is simple, and the prepared high-temperature superconducting REBCO thin film has sharp cubic orientation and excellent superconducting performance, and improves the current-carrying performance of the high-temperature superconducting REBCO thin film at 77K.

Description

A kind of preparation method of high temperature superconducting REBCO film

technical field

The invention belongs to the technical field of high-temperature superconducting materials, and in particular relates to a preparation method of a high-temperature superconducting REBCO thin film.

Background technique

The coated conductor is a multi-layer composite material composed of metal substrate/buffer layer/superconducting layer/protective layer. Due to its excellent current-carrying capacity under high fields, it will be the only hope for high-temperature superconducting materials to truly realize the application of strong electricity in the liquid nitrogen temperature zone. In recent years, it has been the core superconducting material developed by developed countries. At present, the preparation of REBa ₂ Cu ₃ O _y (REBCO) superconducting layer by low-cost chemical solution deposition technology has become one of the research hotspots.

The preparation of high-temperature superconducting REBCO thin films by chemical solution deposition generally includes the steps of precursor solution preparation, coating, pyrolysis, crystallization, and oxygen penetration. According to the phase formation mechanism of the superconducting layer, there are roughly two types. The first one uses a fluorine-free precursor to obtain a fluorine-free precursor solution. The phase formation process is the decomposition of the precursor to form BaCO ₃ , CuO, and RE ₂ O ₃ . These three compounds react to form a REBCO superconducting phase. The _second one uses fluorine-containing precursors to prepare traditional perfluorinated precursor solutions, and the phase formation mechanism is "BaF2 mechanism". That is, the fluorine-containing precursor is decomposed into BaF ₂ , CuO, and RE ₂ O ₃ , and BaF ₂ is converted into BaO by reacting with water, and further reacts with CuO and RE ₂ O ₃ , finally forming the REBCO superconducting phase. These two methods have certain defects. The first method contains barium carbonate which is difficult to decompose during the preparation process. Generally, a higher crystallization temperature is required to completely remove it. Residual carbonate will lead to a decrease in the performance of the REBCO superconducting film. . In the second method, the fluorine content will lead to excessive liquid phase formation in the phase formation process, non-oriented nucleation, slow growth, and reduced performance.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for preparing a high-temperature superconducting REBCO thin film for the above-mentioned deficiencies in the prior art. This method prepares the REBCO fluorine-free/fluorine-containing double-layer precursor film, which can promote the biaxial Orientation nucleation avoids residual barium carbonate from degrading the performance of superconducting thin films. At the same time, as the fluorine in the upper fluorine-containing precursor film gradually diffuses to the lower fluorine-free precursor film, the fluorine content in the upper fluorine-containing precursor film decreases, which is beneficial to reduce the liquid phase in the phase formation process of the upper fluorine-containing precursor film and reduce any shape. Nuclei, forming epitaxial rapid growth.

In order to solve the above-mentioned technical problems, the technical scheme adopted in the present invention is: a kind of preparation method of high-temperature superconducting REBCO film, it is characterized in that, this method comprises the following steps:

Step 1. Prepare fluorine-free precursor solution: Dissolve RE propionate, barium propionate, and copper propionate in a mixed solvent of propionic acid and ethanol according to the atomic ratio of RE: Ba: Cu = 1: 1.75: 3. Stirring at 40°C to 100°C until completely dissolved to obtain a fluorine-free precursor solution with a total molar concentration of cations of 1.5 mol/L; the volume ratio of propionic acid and ethanol in the mixed solvent is 1: (1 to 10); The propionate of RE is yttrium propionate or gadolinium propionate;

Step 2, preparation of fluorine-containing precursor solution: dissolving propionate of RE, organic salt of barium, copper propionate in propionic acid and ethanol by the atomic ratio of RE: Ba: Cu=1: (1.5～2): 3 In the mixed solvent, stir until completely dissolved at 40°C to 100°C to obtain a fluorine-containing precursor solution with a total cation molar concentration of 1.5mol/L to 2mol/L; the volume ratio of propionic acid and ethanol in the mixed solvent 1: (1-10); the propionate of RE is yttrium propionate or gadolinium propionate; the organic salt of barium is barium trifluoroacetate or a mixture of barium trifluoroacetate and barium propionate;

The propionate of RE described in step 2 is the same as the propionate of RE described in step 1;

Step 3. Preparation of fluorine-free single-layer precursor film: uniformly coat the fluorine-free precursor solution described in step 1 on the LaAlO ₃ substrate by spin coating, and then place it in a quartz tube furnace at a temperature of 120°C to 200°C , and a humid oxygen atmosphere is passed into the quartz tube furnace, the temperature is raised to 400°C-500°C at a rate of 5°C/min, the temperature is kept constant for 10min, and the furnace is cooled to room temperature to obtain a fluorine-free single-layer precursor film;

Step 4. Preparation of fluorine-free/fluorine-containing double-layer precursor film: the fluorine-containing precursor solution described in step 2 is evenly coated on the fluorine-free single-layer precursor film described in step 3 by spin coating, and then placed at a temperature of 120°C-200°C quartz tube furnace, and a humid oxygen atmosphere is introduced into the quartz tube furnace, the temperature is raised to 400°C-500°C at a rate of 5°C/min, the temperature is kept for 10 minutes, and the furnace is cooled to room temperature Obtain fluorine-free/fluorine-containing double-layer precursor film;

Step 5, heat treatment for crystallization: place the fluorine-free/fluorine-containing double-layer precursor film in step 4 in a quartz tube furnace, feed moist argon-oxygen mixed gas into the quartz tube furnace, and then use 10 The rate of ℃/min～100℃/min is raised to 770℃～810℃, and the temperature is kept for 1h～2h. When the furnace temperature drops to 450℃, the temperature is kept for 1h for oxygen infiltration treatment. After cooling to room temperature with the furnace, the critical temperature is obtained in liquid nitrogen. High temperature superconducting REBCO thin film above temperature (77K).

The above method for preparing a high-temperature superconducting REBCO thin film is characterized in that the stirring time in step 1 and step 2 is both 1 h to 3 h.

The above-mentioned method for preparing a high-temperature superconducting REBCO thin film is characterized in that the molar percentage of barium trifluoroacetate in the organic salt of barium in step 2 is not less than 15%.

The above method for preparing a high-temperature superconducting REBCO thin film is characterized in that the rotational speed of the spin coating in steps 3 and 4 is 500r/min-4500r/min, and the spin-coating time is 30s-180s.

The method for preparing the above-mentioned high-temperature superconducting REBCO thin film is characterized in that the volume percentage of oxygen in the moist oxygen atmosphere described in steps 3 and 4 is 97%-98%, and the balance is water vapor.

The method for preparing the above-mentioned high-temperature superconducting REBCO film is characterized in that the volume percentage of argon in the moist argon-oxygen mixture described in step five is 95.73% to 98.78%, and the volume percentage of oxygen is 0.02% to 0.07%, the balance is water vapor.

Compared with the prior art, the present invention has the following advantages:

1. The present invention has prepared a fluorine-free/fluorine-containing double-layer precursor film of a REBCO film. The lower layer of the precursor film is a fluorine-free precursor film, and the upper layer is a fluorine-containing precursor film. The fluorine in the upper fluorine-containing precursor film diffuses to the lower layer without In the fluorine precursor film, the carbon content in the lower fluorine-free precursor film is suppressed, which can promote the nucleation of biaxial orientation in the lower fluorine-free precursor film, and avoid the residual barium carbonate from reducing the superconducting performance of the superconducting film. The fluorine in the precursor film gradually diffuses to the lower fluorine-free precursor film, and the fluorine content in the upper precursor film decreases, which is beneficial to reduce the liquid phase in the phase formation process, reduce the nucleation of any body, and form epitaxial rapid growth. The high-temperature superconductor produced by the present invention REBCO thin film solves the problem of poor superconducting performance of REBCO thin film prepared by traditional fluorine-free precursor or perfluorinated precursor.

2. The fluorine diffusion in the fluorine-free/fluorine-containing double-layer precursor film of the REBCO thin film of the present invention can form a fluorine gradient in the double-layer precursor film, weaken the influence of the superconducting layer interface, and avoid copper enrichment at the interface of the upper fluorine-containing precursor film. Set, is conducive to the epitaxial growth across the interface, so that the superconducting film into a whole. By reducing void defects in the superconducting thin film, the uniformity of the high-temperature superconducting thin film is improved, and the superconducting performance of the high-temperature superconducting thin film is improved as a whole.

3. The preparation method of the present invention is simple, and the prepared high-temperature superconducting REBCO film has a sharp cubic orientation, has good superconducting properties, and improves the current-carrying performance of the high-temperature superconducting REBCO film at 77K by improving the structure of the superconducting film .

The technical solutions of the present invention will be further described in detail below with reference to the drawings and embodiments.

Description of drawings

Fig. 1 is the X-ray diffraction pattern of the high temperature superconducting YBCO thin film prepared in Example 1 of the present invention.

Fig. 2 is a scanning electron microscope spectrum of the high-temperature superconducting YBCO thin film prepared in Example 1 of the present invention.

Fig. 3 is an X-ray diffraction pattern of the high-temperature superconducting GdBCO thin film prepared in Example 2 of the present invention.

Fig. 4 is a scanning electron microscope spectrum of the high-temperature superconducting GdBCO thin film prepared in Example 2 of the present invention.

detailed description

Example 1

The method for preparing the high-temperature superconducting YBCO film in this embodiment comprises the following steps:

Step 1. Preparation of fluorine-free precursor solution: Dissolve yttrium propionate, barium propionate, and copper propionate in a mixed solvent of propionic acid and ethanol according to the atomic ratio of Y:Ba:Cu=1:1.75:3. Under the condition of stirring for 2h to completely dissolve, the total cation molar concentration is 1.5mol/L fluorine-free precursor solution; the volume ratio of propionic acid and ethanol in the mixed solvent is 1:5.5;

Step 2, preparation of fluorine-containing precursor solution: dissolve the organic salt of yttrium propionate, barium, copper propionate in the mixed solvent of propionic acid and ethanol by Y:Ba:Cu=1:1.75:3 atomic ratio, at 70 Stirring under the condition of ℃ for 2h until completely dissolved, the fluorine-containing precursor solution with a total molar concentration of cations of 1.8mol/L was obtained; the volume ratio of propionic acid and ethanol in the mixed solvent was 1:5.5; the organic salt of barium was The mixture of barium trifluoroacetate and barium propionate, the molar percentage of barium trifluoroacetate in the organic salt of barium is 60%;

Step 3. Preparation of fluorine-free single-layer precursor film: the fluorine-free precursor solution described in step 1 was evenly coated on the _LaAlO3 substrate by spin coating, and then placed in a quartz tube furnace with a temperature of 160 ° C, and heated to A humid oxygen atmosphere is introduced into the quartz tube furnace, the temperature is raised to 450°C at a rate of 5°C/min, the temperature is kept constant for 10 minutes, and the fluorine-free single-layer precursor film is obtained by cooling to room temperature with the furnace; the spin-coating speed is 2500rpm , the time of the spin coating is 105s; the volume percentage of oxygen in the moist oxygen atmosphere is 97.5%, and the balance is water vapor;

Step 4. Preparation of fluorine-free/fluorine-containing double-layer precursor film: the fluorine-containing precursor solution described in step 2 is evenly coated on the fluorine-free single-layer precursor film described in step 3 by spin coating, and then placed at a temperature of 160°C quartz tube furnace, and a humid oxygen atmosphere is passed into the quartz tube furnace, the temperature is raised to 450°C at a rate of 5°C/min, the temperature is kept constant for 10min, and the furnace is cooled to room temperature to obtain fluorine-free/fluorine-containing Double-layer precursor film; the rotating speed of the spin coating is 2500rpm, and the spin coating time is 105s; the volume percentage of oxygen in the humid oxygen atmosphere is 97.5%, and the balance is water vapor;

Step 5, crystallization heat treatment: place the fluorine-free/fluorine-containing double-layer precursor film in the step 4 in a quartz tube furnace, pass a moist argon-oxygen mixture into the quartz tube furnace, and then Raise the temperature to 790°C at the rate of ℃/min, keep it warm for 1.5h, keep it warm for 1h when the furnace temperature drops to 450°C, and carry out oxygen permeation treatment, then cool down to room temperature with the furnace, and obtain a high-temperature superconductor with a critical temperature above the liquid nitrogen temperature (77K) YBCO film; the volume percentage of argon in the moist argon-oxygen mixture is 97.23%, the volume percentage of oxygen is 0.04%, and the balance is water vapor.

Fig. 1 is the X-ray diffraction spectrum of the high-temperature superconducting YBCO thin film that the embodiment of the present invention 1 prepares, can find out from Fig. 1 that the YBCO thin film of preparation has (00l) peak, and basically do not have other miscellaneous phase peaks, show to have good c-axis Orientation, which shows that the fluorine-free/fluorine-containing bilayer precursor film promotes the c-axis orientation nucleation and growth of the YBCO film. Fig. 2 is the scanning electron microscope atlas of the high-temperature superconducting YBCO film that the embodiment of the present invention 1 prepares, as can be seen from Fig. 2, YBCO film surface does not have a-axis grain, shows that high-temperature superconducting YBCO film has good biaxial orientation, and traditional In the method for preparing YBCO film, the volatilization of high fluorine-containing gas will cause many holes to appear on the film. Compared with it, the surface of YBCO prepared in this example has a small amount of holes, indicating that the fluorine-free/fluorine-containing double-layer precursor film really affects And the fluorine content of the high-temperature superconducting YBCO thin film is reduced, and the holes formed due to the volatilization of impurity gases are suppressed.

The high-temperature superconducting YBCO film prepared in this example has a sharp c-axis orientation, less holes and a flat surface, and the critical current density of the superconducting layer at 77K self-field reaches 3MA/cm ² .

Example 2

The method for preparing the high-temperature superconducting GdBCO film in this embodiment comprises the following steps:

Step 1. Preparation of fluorine-free precursor solution: Dissolve gadolinium propionate, barium propionate, and copper propionate in a mixed solvent of propionic acid and ethanol according to the atomic ratio of Gd:Ba:Cu=1:1.75:3. Under the condition of stirring for 3h to completely dissolve, the total cation molar concentration is 1.5mol/L fluorine-free precursor solution; the volume ratio of propionic acid and ethanol in the mixed solvent is 1:5;

Step 2, preparation of fluorine-containing precursor solution: dissolving gadolinium propionate, organic salt of barium, and copper propionate in a mixed solvent of propionic acid and ethanol at an atomic ratio of Gd:Ba:Cu=1:1.8:3, Stirring under the condition of ℃ for 3h until completely dissolved, the fluorine-containing precursor solution with a total molar concentration of cations of 1.8mol/L was obtained; the volume ratio of propionic acid and ethanol in the mixed solvent was 1:5; the organic salt of barium was The mixture of barium trifluoroacetate and barium propionate; the molar percentage of barium trifluoroacetate in the organic salt of barium is 50%;

Step 3. Preparation of fluorine-free single-layer precursor film: the fluorine-free precursor solution described in step 1 was evenly coated on the _LaAlO3 substrate by spin coating, and then placed in a quartz tube furnace with a temperature of 160 ° C, and heated to A humid oxygen atmosphere was introduced into the quartz tube furnace, the temperature was raised to 400°C at a rate of 5°C/min, the temperature was kept constant for 10 minutes, and the fluorine-free single-layer precursor film was obtained by cooling to room temperature with the furnace; the spin-coating speed was 3000rpm , the time of the spin coating is 105s; the volume percentage of oxygen in the moist oxygen atmosphere is 98%, and the balance is water vapor;

Step 4. Preparation of fluorine-free/fluorine-containing double-layer precursor film: the fluorine-containing precursor solution described in step 2 is evenly coated on the fluorine-free single-layer precursor film described in step 3 by spin coating, and then placed at a temperature of 160°C quartz tube furnace, and a humid oxygen atmosphere is passed into the quartz tube furnace, the temperature is raised to 400°C at a rate of 5°C/min, the temperature is kept constant for 10min, and the furnace is cooled to room temperature to obtain fluorine-free/fluorine-containing Double-layer precursor film; the rotating speed of the spin coating is 3000rpm, and the spin coating time is 105s; the volume percentage of oxygen in the humid oxygen atmosphere is 98%, and the balance is water vapor;

Step 5, heat treatment for crystallization: place the fluorine-free/fluorine-containing double-layer precursor film in step 4 in a quartz tube furnace, feed moist argon-oxygen mixed gas into the quartz tube furnace, and then Raise the temperature to 810°C at the rate of ℃/min, keep it warm for 2 hours, keep it warm for 1 hour when the furnace temperature drops to 450°C, and carry out oxygen permeation treatment, and cool down to room temperature with the furnace to obtain a high-temperature superconducting GdBCO with a critical temperature above the liquid nitrogen temperature (77K) Film; the volume percentage of argon in the moist argon-oxygen mixture is 97%, the volume percentage of oxygen is 0.05%, and the balance is water vapor.

Fig. 3 is the X-ray diffraction spectrum of the high-temperature superconducting GdBCO thin film that the embodiment of the present invention 2 prepares, as can be seen from Fig. 3, the GdBCO thin film that makes has (00l) peak, and does not have other miscellaneous phase peaks substantially, shows that has good c-axis orientation, which shows that the fluorine-free/fluorine-containing bilayer precursor film promotes the c-axis orientation nucleation and growth of GdBCO thin films. Fig. 4 is the scanning electron microscope atlas of the high-temperature superconducting GdBCO film prepared in Example 2 of the present invention. As can be seen from Fig. 4, the surface of the GdBCO film has no a-axis crystals and basically no holes, indicating that the film has good biaxial orientation and good microstructure.

The high-temperature superconducting GdBCO thin film prepared in this example has sharp c-axis orientation, flat surface, good microscopic morphology, and the critical current density reaches 2MA/cm ² at 77K self-field.

Example 3

The method for preparing the high-temperature superconducting YBCO film in this embodiment comprises the following steps:

Step 1. Preparation of fluorine-free precursor solution: Dissolve yttrium propionate, barium propionate, and copper propionate in a mixed solvent of propionic acid and ethanol according to the atomic ratio of Y:Ba:Cu=1:1.75:3. Under the condition of stirring for 1.5h to completely dissolve, the total cation molar concentration is 1.5mol/L fluorine-free precursor solution; the volume ratio of propionic acid and ethanol in the mixed solvent is 1:8;

Step 2, preparation of fluorine-containing precursor solution: dissolving the organic salt of yttrium propionate, barium, copper propionate in the mixed solvent of propionic acid and ethanol by the atomic ratio of Y: Ba: Cu=1: 1.75: 3, at 80 Stirring under the condition of ℃ for 2h until completely dissolved, the fluorine-containing precursor solution with a total molar concentration of cations of 1.8mol/L was obtained; the volume ratio of propionic acid and ethanol in the mixed solvent was 1:8; the organic salt of barium was The mixture of barium trifluoroacetate and barium propionate, the molar percentage of barium trifluoroacetate in the organic salt of barium is 75%;

Step 3. Preparation of fluorine-free single-layer precursor film: the fluorine-free precursor solution described in step ₁ was uniformly coated on the LaAlO substrate by spin coating, and then placed in a quartz tube furnace at a temperature of 180 ° C, and heated to A humid oxygen atmosphere was introduced into the quartz tube furnace, the temperature was raised to 420°C at a rate of 5°C/min, the temperature was kept constant for 10 minutes, and the fluorine-free single-layer precursor film was obtained by cooling to room temperature with the furnace; the spin-coating speed was 3000rpm , the time of the spin coating is 120s; the volume percentage of oxygen in the moist oxygen atmosphere is 97%, and the balance is water vapor;

Step 4. Preparation of fluorine-free/fluorine-containing double-layer precursor film: the fluorine-containing precursor solution described in step 2 is evenly coated on the fluorine-free single-layer precursor film described in step 3 by spin coating, and then placed at a temperature of A quartz tube furnace at 140°C, and a humid oxygen atmosphere is introduced into the quartz tube furnace, the temperature is raised to 480°C at a rate of 5°C/min, the temperature is kept constant for 10min, and the furnace is cooled to room temperature to obtain fluorine-free/fluorine-containing A double-layer precursor film; the rotational speed of the spin coating is 2500rpm, and the spin coating time is 150s; the volume percentage of oxygen in the humid oxygen atmosphere is 97%, and the balance is water vapor;

Step 5, heat treatment for crystallization: place the fluorine-free/fluorine-containing double-layer precursor film in step 4 in a quartz tube furnace, feed moist argon-oxygen mixed gas into the quartz tube furnace, and then Raise the temperature to 800°C at the rate of ℃/min, keep it warm for 1.5h, keep it warm for 1h when the furnace temperature drops to 450°C, and carry out oxygen permeation treatment, then cool down to room temperature with the furnace, and the critical temperature is above the liquid nitrogen temperature (77K) to obtain high-temperature superconductivity YBCO film; the volume percentage of argon in the moist argon-oxygen mixture is 97%, the volume percentage of oxygen is 0.05%, and the balance is water vapor.

The high-temperature superconducting YBCO film prepared in this example has a sharp c-axis orientation, smooth surface, and good microscopic morphology. The critical current density at 77K self-field reaches 2.6MA/cm ² .

Example 4

The method for preparing the high-temperature superconducting GdBCO film in this embodiment comprises the following steps:

Step 1. Preparation of fluorine-free precursor solution: Dissolve gadolinium propionate, barium propionate, and copper propionate in a mixed solvent of propionic acid and ethanol according to the atomic ratio of Gd:Ba:Cu=1:1.75:3. Under the condition of stirring for 3h to completely dissolve, the total cation molar concentration is 1.5mol/L fluorine-free precursor solution; the volume ratio of propionic acid and ethanol in the mixed solvent is 1:7;

Step 2, preparation of fluorine-containing precursor solution: dissolving gadolinium propionate, barium trifluoroacetate, and copper propionate in a mixed solvent of propionic acid and ethanol at an atomic ratio of Gd:Ba:Cu=1:2:3, Stirring under the condition of ℃ for 3h until completely dissolved, the fluorine-containing precursor solution with a total molar concentration of cations of 1.5mol/L was obtained; the volume ratio of propionic acid and ethanol in the mixed solvent was 1:7;

Step 3. Preparation of fluorine-free single-layer precursor film: the fluorine-free precursor solution described in step ₁ was evenly coated on the LaAlO substrate by spin coating, and then placed in a quartz tube furnace at a temperature of 200 ° C, and heated to A humid oxygen atmosphere is introduced into the quartz tube furnace, the temperature is raised to 400°C at a rate of 5°C/min, the temperature is kept constant for 10 minutes, and the fluorine-free single-layer precursor film is obtained by cooling to room temperature with the furnace; the spin-coating speed is 2500rpm , the spin-coating time is 180s; the volume percentage of oxygen in the humid oxygen atmosphere is 97%, and the balance is water vapor;

Step 4. Preparation of fluorine-free/fluorine-containing double-layer precursor film: the fluorine-containing precursor solution described in step 2 is evenly coated on the fluorine-free single-layer precursor film described in step 3 by spin coating, and then placed at a temperature of 200°C quartz tube furnace, and a humid oxygen atmosphere is passed into the quartz tube furnace, the temperature is raised to 400°C at a rate of 5°C/min, the temperature is kept constant for 10min, and the furnace is cooled to room temperature to obtain fluorine-free/fluorine-containing A double-layer precursor film; the rotational speed of the spin coating is 2500rpm, and the spin coating time is 180s; the volume percentage of oxygen in the humid oxygen atmosphere is 97%, and the balance is water vapor;

Step 5, heat treatment for crystallization: place the fluorine-free/fluorine-containing double-layer precursor film in step 4 in a quartz tube furnace, feed moist argon-oxygen mixed gas into the quartz tube furnace, and then use 10 Raise the temperature to 810°C at the rate of ℃/min, keep it for 1h, keep it for 1h when the furnace temperature drops to 450°C, and carry out oxygen permeation treatment, then cool down to room temperature with the furnace, and obtain a high-temperature superconducting GdBCO with a critical temperature above the liquid nitrogen temperature (77K) Film; the volume percentage of argon in the moist argon-oxygen mixture is 98.78%, the volume percentage of oxygen is 0.05%, and the balance is water vapor.

The high-temperature superconducting GdBCO film prepared in this example has a sharp c-axis orientation, smooth surface, and good microscopic morphology. The critical current density at 77K self-field reaches 2.1MA/cm ² .

Example 5

The method for preparing the high-temperature superconducting YBCO film in this embodiment comprises the following steps:

Step 1. Preparation of fluorine-free precursor solution: Dissolve yttrium propionate, barium propionate, and copper propionate in a mixed solvent of propionic acid and ethanol according to the atomic ratio of Y:Ba:Cu=1:1.75:3. Under the condition of stirring for 3h to completely dissolve, the total cation molar concentration is 1.5mol/L fluorine-free precursor solution; the volume ratio of propionic acid and ethanol in the mixed solvent is 1:10;

Step 2, preparing fluorine-containing precursor solution: dissolving yttrium propionate, barium trifluoroacetate, and copper propionate in a mixed solvent of propionic acid and ethanol at an atomic ratio of Y:Ba:Cu=1:2:3, and Stirring under the condition of ℃ for 3h until completely dissolved, obtaining a fluorine-containing precursor solution with a total molar concentration of cations of 2mol/L; the volume ratio of propionic acid and ethanol in the mixed solvent is 1:10;

Step 3. Preparation of fluorine-free single-layer precursor film: the fluorine-free precursor solution described in step ₁ was evenly coated on the LaAlO substrate by spin coating, and then placed in a quartz tube furnace at a temperature of 200 ° C, and heated to A humid oxygen atmosphere was introduced into the quartz tube furnace, the temperature was raised to 500°C at a rate of 5°C/min, the temperature was kept constant for 10 minutes, and the fluorine-free single-layer precursor film was obtained by cooling to room temperature with the furnace; the spin-coating speed was 4500rpm , the spin coating time is 30s; the volume percentage of oxygen in the moist oxygen atmosphere is 98%, and the balance is water vapor;

Step 4. Preparation of fluorine-free/fluorine-containing double-layer precursor film: the fluorine-containing precursor solution described in step 2 is evenly coated on the fluorine-free single-layer precursor film described in step 3 by spin coating, and then placed at a temperature of A quartz tube furnace at 200°C, and a humid oxygen atmosphere is introduced into the quartz tube furnace, the temperature is raised to 500°C at a rate of 5°C/min, the temperature is kept constant for 10min, and the furnace is cooled to room temperature to obtain fluorine-free/fluorine-containing A double-layer precursor film; the rotational speed of the spin coating is 4500rpm, and the spin coating time is 30s; the volume percentage of oxygen in the humid oxygen atmosphere is 98%, and the balance is water vapor;

Step 5, crystallization heat treatment: place the fluorine-free/fluorine-containing double-layer precursor film in the step 4 in a quartz tube furnace, pass a moist argon-oxygen gas mixture into the quartz tube furnace, and then use 100 Raise the temperature to 810°C at the rate of ℃/min, keep it warm for 1h, keep it warm for 1h when the furnace temperature drops to 450°C, and carry out oxygen permeation treatment, then cool down to room temperature with the furnace, and obtain a high-temperature superconducting YBCO with a critical temperature above the liquid nitrogen temperature (77K) Film; the volume percentage of argon in the moist argon-oxygen mixture is 98.78%, the volume percentage of oxygen is 0.07%, and the balance is water vapor.

The high-temperature superconducting YBCO film prepared in this example has good c-axis orientation and biaxial texture, and the surface is flat. The critical current density of the superconducting film under 77K self-field reaches 2.7 MA/cm ² .

Example 6

The method for preparing the high-temperature superconducting YBCO film in this embodiment comprises the following steps:

Step 1. Preparation of fluorine-free precursor solution: Dissolve yttrium propionate, barium propionate, and copper propionate in a mixed solvent of propionic acid and ethanol according to the atomic ratio of Y:Ba:Cu=1:1.75:3, and heat at 100°C Under the condition of stirring for 1h to completely dissolve, the total cation molar concentration is 1.5mol/L fluorine-free precursor solution; the volume ratio of propionic acid and ethanol in the mixed solvent is 1:1;

Step 2, preparation of fluorine-containing precursor liquid: the organic salt of yttrium propionate, barium, copper propionate are dissolved in the mixed solvent of propionic acid and ethanol by the atomic ratio of Y:Ba:Cu=1:1.5:3, at 100 Stirring under the condition of ℃ for 1h until completely dissolved, the fluorine-containing precursor solution with a total molar concentration of cations of 1.5mol/L was obtained; the volume ratio of propionic acid and ethanol in the mixed solvent was 1:10; the organic salt of barium was A mixture of barium trifluoroacetate and barium propionate, the molar percentage of barium trifluoroacetate in the organic salt of barium is 15%;;

Step 3. Preparation of fluorine-free single-layer precursor film: the fluorine-free precursor solution described in step 1 was evenly coated on the _LaAlO3 substrate by spin coating, and then placed in a quartz tube furnace with a temperature of 120 °C, and heated to A humid oxygen atmosphere was introduced into the quartz tube furnace, the temperature was raised to 400°C at a rate of 5°C/min, and the temperature was kept constant for 10 minutes, and then cooled to room temperature with the furnace to obtain a fluorine-free single-layer precursor film; the spin-coating speed was 500rpm , the spin-coating time is 180s; the volume percentage of oxygen in the humid oxygen atmosphere is 97%, and the balance is water vapor;

Step 4. Preparation of fluorine-free/fluorine-containing double-layer precursor film: the fluorine-containing precursor solution described in step 2 is evenly coated on the fluorine-free single-layer precursor film described in step 3 by spin coating, and then placed at a temperature of 120°C quartz tube furnace, and a humid oxygen atmosphere is passed into the quartz tube furnace, the temperature is raised to 400°C at a rate of 5°C/min, the temperature is kept constant for 10min, and the furnace is cooled to room temperature to obtain fluorine-free/fluorine-containing A double-layer precursor film; the rotational speed of the spin coating is 500rpm, and the spin coating time is 180s; the volume percentage of oxygen in the humid oxygen atmosphere is 97%, and the balance is water vapor;

Step 5, heat treatment for crystallization: place the fluorine-free/fluorine-containing double-layer precursor film in step 4 in a quartz tube furnace, feed moist argon-oxygen mixed gas into the quartz tube furnace, and then use 10 Raise the temperature to 770°C at the rate of ℃/min, keep it warm for 2 hours, keep it warm for 1 hour when the furnace temperature drops to 450°C, and carry out oxygen permeation treatment, and cool down to room temperature with the furnace to obtain a high-temperature superconducting YBCO with a critical temperature above the liquid nitrogen temperature (77K) Film; the volume percentage of argon in the moist argon-oxygen mixture is 95.73%, the volume percentage of oxygen is 0.02%, and the balance is water vapor.

The high-temperature superconducting YBCO film prepared in this example has good c-axis orientation and biaxial texture, and the surface is flat. The critical current density of the superconducting film under 77K self-field reaches 2.5 MA/cm ² .

Example 7

The method for preparing the high-temperature superconducting GdBCO film in this embodiment comprises the following steps:

Step 1. Preparation of fluorine-free precursor solution: dissolving gadolinium propionate, barium propionate, and copper propionate in a mixed solvent of propionic acid and ethanol according to the atomic ratio of Gd:Ba:Cu=1:1.75:3, at 60°C Under the condition of stirring for 2h to completely dissolve, the total cation molar concentration is 1.5mol/L fluorine-free precursor solution; the volume ratio of propionic acid and ethanol in the mixed solvent is 1:3;

Step 2, preparation of fluorine-containing precursor solution: dissolve gadolinium propionate, organic salt of barium, and copper propionate in a mixed solvent of propionic acid and ethanol at an atomic ratio of Gd:Ba:Cu=1:2:3, and Stirring under the condition of ℃ for 2h until completely dissolved, the fluorine-containing precursor solution with a total molar concentration of cations of 2mol/L was obtained; the volume ratio of propionic acid and ethanol in the mixed solvent was 1:3; the organic salt of barium was three A mixture of barium fluoroacetate and barium propionate; the molar percentage of barium trifluoroacetate in the organic salt of barium is 35%;

Step 3. Preparation of fluorine-free single-layer precursor film: the fluorine-free precursor solution described in step 1 was evenly coated on the _LaAlO3 substrate by spin coating, and then placed in a quartz tube furnace with a temperature of 140 °C, and heated to A humid oxygen atmosphere is introduced into the quartz tube furnace, the temperature is raised to 480°C at a rate of 5°C/min, the temperature is kept constant for 10 minutes, and the fluorine-free single-layer precursor film is obtained by cooling to room temperature with the furnace; the spin-coating speed is 4500rpm , the time of the spin coating is 120s; the volume percentage of oxygen in the moist oxygen atmosphere is 98%, and the balance is water vapor;

Step 4. Preparation of fluorine-free/fluorine-containing double-layer precursor film: the fluorine-containing precursor solution described in step 2 is evenly coated on the fluorine-free single-layer precursor film described in step 3 by spin coating, and then placed at a temperature of A quartz tube furnace at 180°C, and a humid oxygen atmosphere is introduced into the quartz tube furnace, the temperature is raised to 420°C at a rate of 5°C/min, the temperature is kept constant for 10min, and the furnace is cooled to room temperature to obtain fluorine-free/fluorine-containing A double-layer precursor film; the rotational speed of the spin coating is 4500rpm, and the spin coating time is 120s; the volume percentage of oxygen in the humid oxygen atmosphere is 98%, and the balance is water vapor;

Step 5, crystallization heat treatment: place the fluorine-free/fluorine-containing double-layer precursor film in the step 4 in a quartz tube furnace, pass a moist argon-oxygen gas mixture into the quartz tube furnace, and then heat it with 30 Raise the temperature to 810°C at the rate of ℃/min, keep it for 1h, keep it for 1h when the furnace temperature drops to 450°C, and carry out oxygen permeation treatment, then cool down to room temperature with the furnace, and obtain a high-temperature superconducting GdBCO with a critical temperature above the liquid nitrogen temperature (77K) Film; the volume percentage of argon in the moist argon-oxygen mixture is 96%, the volume percentage of oxygen is 0.05%, and the balance is water vapor.

The high-temperature superconducting GdBCO film prepared in this example has good c-axis orientation and biaxial texture, and the surface is flat. The critical current density of the superconducting film under 77K self-field reaches 1.9 MA/cm ² .

The above are only preferred embodiments of the present invention, and do not limit the present invention in any way. All simple modifications, changes and equivalent structural changes made to the above embodiments according to the technical essence of the invention still belong to the technical solution of the present invention. within the scope of protection.

Claims (6)

1. the preparation method of a high-temperature superconductor REBCO thin film, it is characterised in that the method comprises the following steps:

Step one, the floride-free precursor liquid of preparation: by the propionate of RE, barium propionate, propanoic acid copper according to RE: Ba: Cu=1: 1.75: 3 Atomic ratio is dissolved in the mixed solvent of propanoic acid and ethanol, stirs to being completely dissolved under conditions of 40 DEG C～100 DEG C, obtains total Cation mole concentration is the floride-free precursor liquid of 1.5mol/L；In described mixed solvent, the volume ratio of propanoic acid and ethanol is 1: (1～ 10)；The propionate of described RE is propanoic acid yttrium or propanoic acid gadolinium；

Step 2, prepare fluorine-containing precursor liquid: by the propionate of RE, the organic salt of barium, propanoic acid copper by RE: Ba: Cu=1: (1.5～ 2): the atomic ratio of 3 is dissolved in the mixed solvent of propanoic acid and ethanol, stir to being completely dissolved under conditions of 40 DEG C～100 DEG C, Obtain the fluorine-containing precursor liquid that total cation molar concentration is 1.5mol/L～2mol/L；Propanoic acid and ethanol in described mixed solvent Volume ratio is 1: (1～10)；The propionate of described RE is propanoic acid yttrium or propanoic acid gadolinium；The organic salt of described barium be trifluoroacetic acid barium or Person's trifluoroacetic acid barium and the mixture of barium propionate；

The propionate of RE described in step 2 is identical with the propionate of RE described in step one；

Step 3, the floride-free monolayer precursor film of preparation: use spin-coating method to be coated uniformly on precursor liquid floride-free described in step one LaAlO₃On substrate, being subsequently placed in temperature is 120 DEG C～the quartz tube furnace of 200 DEG C, and is passed through in described quartz tube furnace Moist oxygen atmosphere, with the ramp of 5 DEG C/min to 400 DEG C～500 DEG C, constant temperature 10min, cool to room temperature with the furnace and obtain Floride-free monolayer precursor film；

Step 4, floride-free/fluorine-containing double-deck precursor film of preparation: the employing spin-coating method of fluorine-containing precursor liquid described in step 2 is uniformly coated Described in step 3 on floride-free monolayer precursor film, being subsequently placed in temperature is 120 DEG C～the quartz tube furnace of 200 DEG C, and to institute The oxygen atmosphere of humidity it is passed through in stating quartz tube furnace, with the ramp of 5 DEG C/min to 400 DEG C～500 DEG C, constant temperature 10min, Cool to room temperature with the furnace and obtain free-floride/floride-free/fluorine-containing double-deck precursor film of fluorine-containing double-deck precursor film；

Step 5, crystallization and thermal treatment: double-deck precursor film floride-free/fluorine-containing described in step 4 is placed in quartz tube furnace, to institute State quartz tube furnace and be passed through the argon oxygen gas mixture of humidity, the most again with the ramp of 10 DEG C/min～100 DEG C/min to 770 DEG C ～810 DEG C, it is incubated 1h～2h, when furnace temperature is down to 450 DEG C, is incubated 1h carries out oozing oxygen process, cool to room temperature with the furnace, faced Boundary's temperature high-temperature superconductor REBCO thin film more than liquid nitrogen temperature 77K.

The preparation method of a kind of high-temperature superconductor REBCO thin film the most according to claim 1, it is characterised in that step one and The time of stirring described in step 2 is 1h～3h.

The preparation method of a kind of high-temperature superconductor REBCO thin film the most according to claim 1, it is characterised in that in step 2 In the organic salt of described barium, the mole percent of trifluoroacetic acid barium is not less than 15%.

The preparation method of a kind of high-temperature superconductor REBCO thin film the most according to claim 1, it is characterised in that step 3 and The rotating speed of spin coating described in step 4 is 500r/min～4500r/min, and the time of described spin coating is 30s～180s.

The preparation method of a kind of high-temperature superconductor REBCO thin film, it is characterised in that step 3 and step In oxygen atmosphere moist described in rapid four, the volumn concentration of oxygen is 97%～98%, and surplus is steam.

The preparation method of a kind of high-temperature superconductor REBCO thin film, it is characterised in that institute in step 5 Stating the volumn concentration of argon in the argon oxygen gas mixture of humidity is 95.73%～98.78%, and the volumn concentration of oxygen is 0.02%～0.07%, surplus is steam.