Method for improving magnetic flux pinning of yttrium barium copper oxide superconducting thin film through BaMO3 nanocrystalline

Abstract

The invention belongs to the technical field of superconducting materials, and particularly relates to a method for improving yttrium barium copper oxide superconducting thin film magnetic flux pinning through BaMO3 nanocrystals, which comprises the following steps: S1, preparing the BaMO3 nanocrystals, and monodispersing the BaMO3 nanocrystals in ethanol or methanol to obtain BaMO3 dispersion liquid; s2, performing surface modification on the BaMO3 dispersion liquid which is monodispersed in methanol or ethanol by adopting MEEAA (Methyl Ethylenediamine Acrylic Acid); s3, preparing a TFA-REBCO film precursor solution; s4, the modified BaMO3 dispersion liquid is added into the TFA-REBCO thin film precursor liquid; and S5, coating the TFA-REBCO thin film precursor liquid added with the BaMO3 dispersion liquid to form a film, and sequentially performing low-temperature pyrolysis, high-temperature crystallization and oxygen absorption to obtain the REBCO superconducting thin film. The monodisperse BaMO3 nanocrystals with narrow size distribution can be introduced into the REBCO superconducting thin film to improve the magnetic flux pinning capability of the REBCO superconducting thin film in a field, the size height of the introduced nanocrystals is controllable, the nanocrystals can be dispersed and distributed in the thin film without agglomeration, and the current-carrying capability of the REBCO superconducting thin film can be improved under the conditions of 30K and 3T.

Description

Technical Field

[0001] The invention belongs to the technical field of superconducting materials, and in particular relates to a method for improving magnetic flux pinning of yttrium barium copper oxide superconducting films by using BaMO3 nanocrystals. Background Art

[0002] The second generation of high temperature superconducting materials REBCO (REBa2Cu3O 7-δ ,RE=Y or rare earth elements), due to its high critical current and high irreversible field, it has a wide range of applications in the power field such as superconducting magnets;

[0003] The critical current of REBCO superconducting coated conductors drops rapidly in the presence of an external magnetic field, which limits the practical application of REBCO. Due to the movement of magnetic flux vortices within the high-temperature superconducting film, the critical current value decreases significantly with the increase of the external magnetic field, which is not conducive to its application in the field. Therefore, increasing the effective magnetic flux pinning centers in the high-temperature superconducting film can enhance its application potential.

[0004] The TFA-MOD technology route, currently the mainstream chemical preparation method for REBCO, boasts low cost and high efficiency. The conventional method for introducing flux pinning centers in chemical preparation involves doping with heterogeneous elements. However, the growth of heterogeneous nanostructures formed by these elements is generally difficult to control at high temperatures and is significantly affected by fluctuations in sintering conditions. Summary of the Invention

[0005] The present invention aims to provide a method for improving the magnetic flux pinning of yttrium barium copper oxide superconducting films by using BaMO3 nanocrystals. The method can introduce monodisperse BaMO3 nanocrystals with a narrow size distribution into a REBCO superconducting film to enhance its on-site magnetic flux pinning capability. The size of the introduced nanocrystals is highly controllable and can be dispersed in the film without agglomeration. The method can improve the current carrying capacity of the REBCO superconducting film by 50-150% at 30K and 3T.

[0006] The technical solutions adopted by the present invention are as follows:

[0007] A method for improving the magnetic flux pinning of yttrium barium copper oxide superconducting thin films by using BaMO3 nanocrystals, comprising the following steps:

[0008] S1: Monodispersing BaMO3 nanocrystals in ethanol or methanol to obtain a BaMO3 dispersion;

[0009] S2: Surface modification of BaMO3 dispersion monodispersed in methanol or ethanol using MEEAA;

[0010] S3: Prepare TFA-REBCO thin film precursor solution using trifluoroacetic acid-metal organic deposition method;

[0011] S4: adding the modified BaMO3 dispersion into the TFA-REBCO film precursor solution;

[0012] S5: coating a TFA-REBCO thin film precursor solution added with a BaMO3 dispersion to form a film, and sequentially performing low-temperature pyrolysis, high-temperature crystallization, and oxygen absorption to obtain a REBCO superconducting thin film.

[0013] Furthermore, the BaMO3 in S1 is prepared in advance by an organic solvent thermal method.

[0014] Furthermore, when the BaMO3 dispersion in S2 is 10 mmol, the amount of MEEAA used is about 0.5-1.0 mL.

[0015] Furthermore, the BaMO3 nanocrystal is any one of BaZrO3 nanocrystal, BaHfO3 nanocrystal, and BaTiO3 nanocrystal.

[0016] The technical effects achieved by the present invention are:

[0017] The present invention discloses a method for improving the magnetic flux pinning of a yttrium-barium-copper-oxide superconducting film by using BaMO3 nanocrystals. The method first prepares barium titanate, barium zirconate, and barium hafnium oxide nanocrystals and then dopes them with a TFA-REBCO precursor solution to achieve the introduction of a controllable heterogeneous phase, thereby forming effective magnetic flux pinning centers in the high-temperature superconducting film. The method can improve the current carrying capacity of the REBCO superconducting film by 50-150% under 30K and 3T conditions, thereby greatly enhancing its commercial application potential.

[0018] The method of the present invention for improving the magnetic flux pinning of yttrium barium copper oxide superconducting thin films by using BaMO3 nanocrystals has a highly controllable size of the introduced magnetic flux pinning centers. That is, under the premise of achieving monodispersion, the size of the introduced magnetic flux pinning centers is determined only by the added BaMO3 nanocrystals, and the average size of the BaMO3 nanocrystals can be pre-controlled during preparation.

[0019] The method of the present invention for improving the magnetic flux pinning of yttrium barium copper oxide superconducting thin films by using BaMO3 nanocrystals has a simple process, can be produced on a large scale and in batches, and has high commercial practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a TEM image of BaZrO3 nanocrystals prepared in Example 2 of the present invention;

[0021] Figure 2 is a DLS particle size distribution diagram of BaZrO3 nanocrystals in ethanol in Example 2 of the present invention;

[0022] Figure 3is a DLS particle size distribution diagram of BaZrO3 nanocrystals in TFA-REBCO precursor solution in Example 2 of the present invention;

[0023] Figure 4 is the XRD pattern of the REBCO film after adding 5 mol% BaZrO3 nanocrystals in Example 2 of the present invention;

[0024] Figure 5 is a TEM image of the distribution of 5 mol % BaZrO3 nanocrystals in the REBCO crystallized film in Example 2 of the present invention;

[0025] Figure 6 This is a comparison chart of the on-site critical current density of the REBCO film after adding 5 mol% BaZrO3 nanocrystals in Example 2 of the present invention and that of the undoped sample;

[0026] Figure 7 is a TEM image of BaHfO3 nanocrystals prepared in Example 3 of the present invention;

[0027] Figure 8 is a TEM image of the distribution of 15 mol % BaHfO3 nanocrystals in the REBCO crystallized film in Example 3 of the present invention;

[0028] Figure 9 This is a comparison chart of the on-site critical current density of the REBCO film after adding 15 mol % BaHfO 3 nanocrystals in Example 3 of the present invention and the undoped sample. DETAILED DESCRIPTION

[0029] In order to make the purpose and advantages of the present invention more clearly understood, the present invention is described in detail below with reference to the following examples. It should be understood that the following text is only used to describe one or more specific embodiments of the present invention and does not strictly limit the scope of protection of the present invention.

[0030] Example 1:

[0031] A method for improving the magnetic flux pinning of yttrium barium copper oxide superconducting thin films by using BaMO3 nanocrystals, comprising the following steps:

[0032] S1: BaMO3 (M = Ti, Zr, Hf, i.e., BaMO3 is any one of BaZrO3, BaHfO3, and BaTiO3) nanocrystals are prepared in advance by an organic solvent thermal method and monodispersed in ethanol or methanol to obtain a BaMO3 (M = Ti, Zr, Hf) dispersion;

[0033] Wherein, in said S1, an organic solvent thermal method is used to prepare BaMO3 (M=Ti, Zr, Hf) nanocrystals with an average size between 2nm and 15nm;

[0034] The BaMO3 (M = Ti, Zr, Hf) nanocrystals prepared in S1 can be monodispersed in methanol or ethanol after washing and collection, and the concentration of the obtained BaZrO3 dispersion can be as high as 1 mol / L;

[0035] S2: BaMO3 (M = Ti, Zr, Hf) dispersion monodispersed in methanol or ethanol was surface modified using [2-(2-methoxyethoxy)ethoxy]acetic acid (MEEAA) to obtain a precipitate-free and transparent BaMO3 (M = Ti, Zr, Hf) nanocrystal dispersion;

[0036] Here, when the BaMO3 (M = Ti, Zr, Hf) dispersion is 10 mmol, the amount of MEEAA used is about 0.5-1.0 mL;

[0037] S3: preparing a TFA-REBCO thin film precursor solution using a trifluoroacetic acid-metal organic deposition method (TFA-MOD), wherein the fluorine content relative to the Ba content is in the range of 30-60%;

[0038] S4: adding the modified BaMO3 (M = Ti, Zr, Hf) dispersion to the TFA-REBCO thin film precursor in a certain proportion to achieve a monodisperse effect, wherein the doping concentration is in the range of 0-30 mol% according to the element ratio M / Y;

[0039] Here, the agent MEEAA plays a significant role in the dispersion of BaMO3 nanocrystals with a size of 2-15 nm in the precursor solution of REBCO;

[0040] S5: applying a TFA-REBCO thin film precursor solution to which a BaMO3 dispersion solution is added to form a film, and sequentially performing heat treatments such as low-temperature pyrolysis, high-temperature crystallization, and oxygen absorption to obtain a REBCO superconducting thin film.

[0041] In summary, this technical solution achieves the introduction of controllable heterogeneous phases by first preparing barium titanate, barium zirconate and barium hafnate nanocrystals and then doping them with TFA-REBCO precursor liquid, forming effective flux pinning centers in high-temperature superconducting films. Under the conditions of 30K and 3T, the current carrying capacity of the REBCO superconducting film can be increased by 50-150%, greatly improving its commercial application potential. In addition, the size of the introduced flux pinning centers is highly controllable, that is, under the premise of achieving monodispersity, the size of the introduced flux pinning centers is only determined by the added BaMO3 nanocrystals, and the average size of the BaMO3 nanocrystals can be pre-controlled during preparation. The process is simple and can be produced on a large scale and in batches, with high commercial value.

[0042] Example 2:

[0043] like Figure 1-6 As shown, this embodiment discloses in detail a method for improving the magnetic flux pinning of yttrium barium copper oxide superconducting thin films by using BaMO3 nanocrystals based on Example 1, wherein the BaMO3 nanocrystals are BaZrO3 nanocrystals, which specifically includes the following steps:

[0044] S1: 1 mL of zirconium n-butoxide (80 wt%) was added to 8 mL of ethanol under stirring, and then 0.8900 g of barium hydroxide octahydrate Ba(OH)2·8H2O was added to the mixture, and stirring was continued to obtain a milky white turbid liquid. Subsequently, 5 mL of triethylene glycol and 0.75 mL of ammonia water were added, and after stirring evenly, the mixture was transferred to a 25 mL polytetrafluoroethylene-lined reactor, and then covered with a steel jacket and placed in an oven at 180°C for 5-20 h;

[0045] After the reaction is completed, the reaction mixture is taken out, ethyl acetate is added, and the mixture is centrifuged and washed three times. The obtained precipitate is then added to 5 mL of ethanol and ultrasonically treated for 30 minutes. The mixture is then centrifuged at 10,000 rpm for 10 minutes. The supernatant is collected to obtain a monodispersed BaZrO3 nanocrystal ethanol dispersion in ethanol.

[0046] S2: 0.5 mL of MEEAA was added to a 10 mmol BaZrO3 nanocrystal ethanol dispersion for surface modification. A small amount of the BaZrO3 nanocrystal ethanol dispersion sample was then taken for calcination. The mass loss before and after calcination was recorded, and the BaZrO3 concentration in the BaZrO3 nanocrystal ethanol dispersion was calculated.

[0047] S3: Prepare TFA-REBCO thin film precursor solution using trifluoroacetic acid-metal organic deposition method;

[0048] S4: Add MEEAA-modified BaZrO3 nanocrystal ethanol dispersion to TFA-REBCO thin film precursor solution at 5 mol% of RE element in TFA-REBCO thin film precursor solution and stir for more than 1 hour;

[0049] S5: The TFA-REBCO thin film precursor solution containing the above-mentioned BaZrO3 nanocrystal ethanol dispersion is coated with pyrolysis to form a film, and then high-temperature crystallization growth is completed at 780°C and 150ppm nitrogen and oxygen mixed atmosphere, and oxygen absorption treatment is carried out at 450°C in a pure oxygen environment for 1h to obtain a REBCO superconducting film with good c-axis orientation.

[0050] The morphology of BaZrO3 nanocrystals in this example is as follows Figure 1 As shown, the average size is about 8.0nm; the monodisperse effect in ethanol and TFA-REBCO film precursor is as shown Figure 2 and Figure 3 ;in, Figure 2 The single peak in the middle indicates that the BaZrO3 nanocrystals exist in a monodispersed form in the solution, among which, Figure 3 The single peak in the middle indicates that BaZrO3 nanocrystals exist in a monodispersed form in the solution; the XRD pattern of the REBCO film after adding 5 mol% BaZrO3 nanocrystals is as follows Figure 4 The distribution of 5mol% BaZrO3 nanocrystals in REBCO crystallized film is shown in Figure 2. Figure 5 The BaZrO3 nanocrystals are randomly dispersed in the crystallized film with a size of about 10nm. The on-site critical current density of the REBCO film with 5mol% BaZrO3 nanocrystals added is compared with that of the undoped sample. Figure 6 .

[0051] Example 3:

[0052] This embodiment discloses in detail a method for improving the magnetic flux pinning of a yttrium barium copper oxide superconducting film by using BaMO3 nanocrystals based on the embodiment 1, wherein the BaMO3 nanocrystals are BaHfO3 nanocrystals, and specifically includes the following steps:

[0053] S1: Add 3 mL of hafnium n-butoxide (Hf: 22.6 wt%) to 10 mL of stirring ethanol, then add 1.2492 g of barium hydroxide octahydrate Ba(OH)2·8H2O to the mixture, followed by 10 mL of triethylene glycol and 1.0 mL of deionized water. After stirring evenly, transfer the mixture to a 50 mL polytetrafluoroethylene-lined reactor, cover it with a steel jacket, and place it in an oven at 180°C for 5-20 hours.

[0054] After the above reaction is completed, the reaction mixture is taken out, ethyl acetate is added, and the mixture is centrifuged and washed three times. The obtained precipitate is then added to 5 mL of ethanol and ultrasonically treated for 30 minutes. Then, the mixture is centrifuged at 10,000 rpm for 10 minutes. The supernatant is taken to obtain a BaHfO3 nanocrystal ethanol dispersion monodispersed in ethanol.

[0055] S2: 0.5 mL of MEEAA was added to a 10 mmol BaHfO3 nanocrystal ethanol dispersion for surface modification. A small amount of the BaHfO3 nanocrystal ethanol dispersion sample was then calcined. The mass loss before and after calcination was recorded, and the BaHfO3 concentration in the BaHfO3 nanocrystal ethanol dispersion was calculated.

[0056] S3: Prepare TFA-REBCO thin film precursor solution using trifluoroacetic acid-metal organic deposition method;

[0057] S4: Add MEEAA-modified BaHfO3 nanocrystal ethanol dispersion to TFA-REBCO thin film precursor solution at an amount of 15 mol% of the RE element in the TFA-REBCO thin film precursor solution and stir for more than 1 hour;

[0058] S5: The TFA-REBCO thin film precursor solution containing the above-mentioned BaHfO3 nanocrystal ethanol dispersion is coated with pyrolysis to form a film, and then high-temperature crystallization growth is completed at 780°C and 150ppm nitrogen and oxygen mixed atmosphere, and oxygen absorption treatment is carried out at 450°C in a pure oxygen environment for 1h to obtain a REBCO superconducting film with good c-axis orientation.

[0059] The morphology of the prefabricated BaHfO3 nanocrystals in Example 2 is as follows: Figure 7 As shown in Figure 2, the average size is about 7.5 nm. The distribution of 15 mol% BaHfO3 nanocrystals in the REBCO crystallized film is shown in Figure 2. Figure 8 , in which BaHfO3 nanocrystals are randomly dispersed in the crystallized film; the on-site critical current density of the REBCO film after adding 15mol% BaHfO3 nanocrystals is compared with that of the undoped sample. Figure 9 .

[0060] The method for improving the magnetic flux pinning of the YBCO superconducting film in the above embodiment can introduce monodisperse BaMO3 nanocrystals with a narrow size distribution into the REBCO superconducting film to improve its in-situ magnetic flux pinning ability. The size of the introduced nanocrystals is highly controllable and can be dispersed in the film without agglomeration.

[0061] The foregoing is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are also within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained herein shall, unless otherwise specified or limited, be implemented in accordance with conventional means in the art.

Claims

1. A method for improving the magnetic flux pinning of yttrium barium copper oxide superconducting thin films by using BaMO3 nanocrystals, characterized in that: The following steps are involved: S1: Monodispersing BaMO3 nanocrystals in ethanol or methanol to obtain a BaMO3 dispersion; S2: Surface modification of BaMO3 dispersion monodispersed in methanol or ethanol using MEEAA; S3: Prepare TFA-REBCO thin film precursor solution using trifluoroacetic acid-metal organic deposition method; S4: adding the modified BaMO3 dispersion into the TFA-REBCO film precursor solution; S5: coating a TFA-REBCO thin film precursor solution added with a BaMO3 dispersion to form a film, and sequentially performing low-temperature pyrolysis, high-temperature crystallization, and oxygen absorption to obtain a REBCO superconducting thin film.

2. The method of claim 1, wherein: The BaMO3 nanocrystals are BaZrO3 nanocrystals.

3. The method of claim 2, wherein: The following steps are involved: S1: Add 1 mL of zirconium n-butoxide to 8 mL of stirring ethanol, then add 0.8900 g of barium hydroxide octahydrate to the mixture and continue stirring to obtain a milky white turbid solution. Then, add 5 mL of triethylene glycol and 0.75 mL of ammonia water. After stirring evenly, transfer the mixture to a 25 mL polytetrafluoroethylene-lined reactor, cover it with a steel jacket, and place it in an oven at 180°C for 5-20 hours. After the reaction is completed, the reaction mixture is taken out, ethyl acetate is added, and the mixture is centrifuged and washed three times. The obtained precipitate is then added to 5 mL of ethanol and ultrasonically treated for 30 minutes. The mixture is then centrifuged at 10,000 rpm for 10 minutes, and the supernatant is collected to obtain a monodispersed BaZrO3 nanocrystal ethanol dispersion in ethanol. S2: 0.5 mL of MEEAA was added to a 10 mmol BaZrO3 nanocrystal ethanol dispersion for surface modification. The BaZrO3 nanocrystal ethanol dispersion was then sampled and calcined. The mass loss before and after calcination was recorded, and the BaZrO3 concentration in the BaZrO3 nanocrystal ethanol dispersion was calculated. S3: Prepare TFA-REBCO thin film precursor solution using trifluoroacetic acid-metal organic deposition method; S4: Add MEEAA-modified BaZrO3 nanocrystal ethanol dispersion to TFA-REBCO thin film precursor solution at 5 mol% of RE element in TFA-REBCO thin film precursor solution and stir for more than 1 hour; S5: The TFA-REBCO thin film precursor solution containing BaZrO3 nanocrystal ethanol dispersion is coated with pyrolysis to form a film, and then high-temperature crystallization growth is completed in a nitrogen and oxygen mixed atmosphere of 780°C and 150ppm, and oxygen absorption treatment is carried out in a pure oxygen environment of 450°C for 1h to obtain a REBCO superconducting thin film.

4. The method of claim 1, wherein: The BaMO3 nanocrystals are BaHfO3 nanocrystals.

5. The method of improving magnetic flux pinning of yttrium barium copper oxide superconducting thin films by using BaMO3 nanocrystals according to claim 4, characterized in that: The following steps are involved: S1: Add 3 mL of hafnium n-butoxide to 10 mL of stirring ethanol, then add 1.2492 g of barium hydroxide octahydrate to the mixture, followed by 10 mL of triethylene glycol and 1.0 mL of deionized water. After stirring evenly, transfer the mixture to a 50 mL polytetrafluoroethylene-lined reactor, cover it with a steel jacket, and place it in an oven at 180°C for 5-20 hours. After the reaction is completed, the reaction mixture is taken out, ethyl acetate is added, and the mixture is centrifuged and washed three times. The resulting precipitate is then added to 5 mL of ethanol and ultrasonically treated for 30 min. The mixture is then centrifuged at 10,000 rpm for 10 min. The supernatant is collected to obtain a monodispersed BaHfO3 nanocrystal ethanol dispersion in ethanol. S2: 0.5 mL of MEEAA was added to a 10 mmol BaHfO3 nanocrystal ethanol dispersion for surface modification. The BaHfO3 nanocrystal ethanol dispersion was then sampled and calcined. The mass loss before and after calcination was recorded, and the BaHfO3 concentration in the BaHfO3 nanocrystal ethanol dispersion was calculated. S3: Prepare TFA-REBCO thin film precursor solution using trifluoroacetic acid-metal organic deposition method; S4: Add MEEAA-modified BaHfO3 nanocrystal ethanol dispersion to TFA-REBCO thin film precursor solution at an amount of 15 mol% of the RE element in the TFA-REBCO thin film precursor solution and stir for more than 1 hour; S5: A TFA-REBCO thin film precursor solution containing a BaHfO3 nanocrystal ethanol dispersion is coated and pyrolyzed to form a film, and then high-temperature crystallization growth is completed at 780°C and a 150ppm nitrogen and oxygen mixed atmosphere, and oxygen absorption treatment is performed at 450°C in a pure oxygen environment for 1h to obtain a REBCO superconducting thin film.

6. The method of claim 1, wherein: The BaMO3 nanocrystal is BaTiO3.

7. The method of claim 1, wherein: The BaMO3 in S1 is prepared in advance by an organic solvent thermal method.

8. The method of claim 1, wherein: When the BaMO3 dispersion in S2 is 10 mmol, the amount of MEEAA used is about 0.5-1.0 mL.

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