Gadolinium ytterbium barium copper oxide superconducting film and preparation method and application thereof

Abstract

The invention belongs to the field of high-temperature superconducting materials, and particularly relates to a gadolinium-ytterbium-barium-copper-oxygen superconducting film and a preparation method and application thereof, and the preparation method comprises the steps: S1, preparing a solution containing 2-thiophenyltrifluoroacetone; s2, adding gadolinium oxide and ytterbium oxide to react with nitric acid to obtain a mixed solution containing gadolinium nitrate and ytterbium nitrate, mixing the solution obtained in S1 with the mixed solution, adding a seed crystal to react, standing, separating and drying to obtain a gadolinium-ytterbium coordination complex; s3, mixing the gadolinium-ytterbium coordination complex obtained in S2, a barium source, a copper source and a solvent, and growing a gadolinium-ytterbium-barium-copper-oxygen superconducting film on the surface of the substrate through an organic metal chemical vapor deposition method by taking oxygen as an oxygen source; the molar ratio of gadolinium nitrate to ytterbium nitrate is (0.7-0.78): (0.22-0.3). The gadolinium-ytterbium coordination complex prepared by the invention is good in volatility and high in thermal stability; the generated film has few impure phases and holes, and the prepared film has a smooth surface and has excellent electrical performance and magnetic field performance under low temperature and high field.

Description

Technical Field

[0001] The invention belongs to the field of high-temperature superconducting materials, and specifically relates to a gadolinium ytterbium barium copper oxide superconducting film and a preparation method and application thereof. Background Art

[0002] Rare earth barium copper oxide (ReBCO) is a key factor in the current carrying of the second generation of high-temperature superconductors. Improving the preparation of coated conductors with excellent superconducting properties not only depends on the improvement of the metal organic chemical vapor deposition (MOCVD) process, but also on the strict control of the quality of raw materials. At present, when using the MOCVD process to prepare ReBCO superconducting tapes at home and abroad, the chemical sources are mainly Ba(THD)2, Y(THD)3, Cu(THD)3, Zr(THD)4 and other chemical sources (THD is tetramethylheptanone). Among them, the addition of Zr(THD)4 can generate BaZrO3 nanocolumns in the ReBCO ceramic layer. This design aims to significantly improve the current carrying capacity and antimagnetic properties of superconducting tapes in low temperature and strong magnetic field environments through the magnetic flux pinning effect.

[0003] However, the practical application of Zr(THD)4 faces two major technical bottlenecks: first, its addition amount in the formula is extremely low (usually at the ppm level), and the process control accuracy requirements are extremely high, making it difficult to control the addition amount; second, the thermal decomposition characteristics of the precursor cause it to have a high weight loss peak in the temperature range of 310-350°C, resulting in a slow evaporation rate and poor stability. These problems directly affect the uniformity of film deposition - in the MOCVD process, the inconsistency of the volatilization of Zr(THD)4 can easily cause the appearance of non-uniform phases on the surface of the ReBCO film (such as impurity precipitation, microscopic holes, and lattice orientation deviations). These microstructural defects will significantly reduce the current transmission efficiency in the superconducting layer, making it difficult for the test data of the final product to meet the stringent requirements of high-end application scenarios such as nuclear magnetic resonance and controlled nuclear fusion. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of existing superconducting films, such as impurities, rough holes, poor electrical and magnetic field properties, and high cost, thereby providing a gadolinium ytterbium barium copper oxide superconducting film and its preparation method and application.

[0005] To this end, the present invention provides the following technical solutions:

[0006] The first aspect of the present invention provides a method for preparing a gadolinium ytterbium barium copper oxide superconducting film, wherein the preparation method comprises the following steps:

[0007] S1, preparing a solution containing 2-thenoyltrifluoroacetone;

[0008] S2, adding gadolinium oxide and ytterbium oxide to react with nitric acid to obtain a mixed solution containing gadolinium nitrate and ytterbium nitrate, mixing the solution obtained in S1 with the mixed solution, adding seed crystals to react, standing, separating and drying to obtain a gadolinium-ytterbium coordination complex;

[0009] S3, mixing the gadolinium-ytterbium coordination complex obtained in S2, a barium source, a copper source and a solvent, and growing a gadolinium-ytterbium-barium-copper-oxygen superconducting film on the surface of the substrate by an organic metal chemical vapor deposition method using oxygen as an oxygen source;

[0010] Wherein, the molar ratio of gadolinium nitrate to ytterbium nitrate is (0.7-0.78):(0.22-0.3).

[0011] In the present invention, in S2, the mixing method is a conventional mixing method, and the mixing is uniform; in S3, the mixing method is a conventional mixing method, typically but not limitingly, the mixing method is stirring, the rotation speed is 40-60r / min, and the stirring time is 4-6h. After mixing, the obtained product is filtered, and the filtrate is collected to obtain a chemical source. Under the conditions of 750-860°C and 99.999% oxygen, the filtrate is vaporized and reacted with oxygen with a purity range of 99.995%-99.999% to generate metal oxides, and then a gadolinium ytterbium barium copper oxide superconducting film is generated on the surface of a substrate (such as a lanthanum manganate substrate).

[0012] In the present invention, 2-thenoyltrifluoroacetone is a binuclear ligand compound, and the molar ratio of the sum of the metal elements of the gadolinium element in the gadolinium nitrate and the ytterbium element in the ytterbium nitrate to 2-thenoyltrifluoroacetone is always 1:3; during the metal organic chemical vapor deposition process, 2-thenoyltrifluoroacetone will decompose under high temperature environment.

[0013] In the present invention, gadolinium oxide and ytterbium oxide react with nitric acid to obtain a mixed solution containing gadolinium nitrate and ytterbium nitrate. This is a conventional reaction in the art. Typically, but not limitingly, 1-10 mol of gadolinium oxide and 30 wt% nitric acid are reacted at a molar ratio of gadolinium oxide to nitric acid of 1:6 at 25°C for 1-2 hours to obtain solution A; 1-10 mol of ytterbium oxide and 30 wt% nitric acid are reacted at a molar ratio of ytterbium oxide to nitric acid of 1:6 at 25°C for 1-2 hours to obtain solution B; solutions A and B are mixed to obtain a mixed solution containing gadolinium nitrate and ytterbium nitrate; gadolinium oxide and ytterbium oxide can also be added to nitric acid at the same time.

[0014] According to the present invention, in S1, the specific steps of preparing include: dissolving 2-thenoyltrifluoroacetone in a first solvent, adding a sodium hydroxide solution, and obtaining a solution containing 2-thenoyltrifluoroacetone.

[0015] According to the present invention, the first solvent is methanol and water, and the volume ratio of methanol to water is 1.2-1.5:1.

[0016] In the present invention, the sodium hydroxide solution reacts with the methanol in the first solvent to generate sodium methoxide, and the sodium methoxide is a catalyst in the reaction of gadolinium nitrate, ytterbium nitrate and TTA.

[0017] Taking ytterbium nitrate as an example, the specific reaction formula is: (1) NaOH+CH3OH+H2O→NaOCH3+2H2O; (2) In the case of NaOCH3 as a catalyst, Yb(NO3)3+3TTA→Yb(TTA)3+3HNO3; Gadolinium nitrate reacts according to the same mechanism. When ytterbium nitrate and gadolinium nitrate are added at the same time, a gadolinium-ytterbium coordination complex is obtained.

[0018] According to the present invention, the concentration of the sodium hydroxide solution is 15-18 mol / L.

[0019] According to the present invention, the volume ratio of the first solvent to the sodium hydroxide solution is 5-8:1.

[0020] According to the present invention, the specific preparation steps of the seed crystals include: at 75-80°C, gadolinium nitrate and 2-thenoyltrifluoroacetone are coordinated to obtain seed crystals, and the molar ratio of gadolinium element to 2-thenoyltrifluoroacetone in gadolinium nitrate is 1:3; the specific reaction solution system is a solution that can dissolve the reactants, typically but not limitingly, a methanol mixed solution, and the volume ratio of methanol, benzene and acetonitrile in the methanol mixed solution is (1000-1200):(5-7):(5-8), the seed crystal preparation reaction is 7-8h to generate Gd(TTA)3 seed crystals, and Gd(TTA)3 seed crystals are used to prepare gadolinium ytterbium coordination complex, gadolinium coordination complex, and ytterbium coordination complex.

[0021] According to the present invention, based on the theoretically calculated mass of the synthesized gadolinium-ytterbium coordination complex, the mass of the seed crystal is 0.1-0.2 wt %.

[0022] In the present invention, because the number of coordination bonds is constant and there is no loss, the structural formula of the final gadolinium-ytterbium coordination complex can be inferred according to the feed ratio. For example, when the molar ratio of gadolinium element to ytterbium element is 0.78:0.22, the structural formula of the final gadolinium-ytterbium coordination complex is inferred to be (Gd 0.78 Yb 0.22 )(TTA)3, the theoretically calculated mass of the synthesized gadolinium-ytterbium coordination complex is (Gd 0.78 Yb 0.22 )(TTA)3 molar amount × (Gd 0.78 Yb 0.22 )(TTA)3 molecular weight.

[0023] According to the present invention, the reaction time is 3-6h.

[0024] According to the present invention, the standing time is 8-10h。

[0025] In the present invention, the timing starts after the white crystal precipitation appears, and the crystals are continuously generated and grow during the static process.

[0026] According to the present invention, the gadolinium ytterbium coordination complex is further subjected to a recrystallization treatment, comprising the following steps: dissolving the gadolinium ytterbium coordination complex in a second solvent and placing the complex for 10-12 hours, filtering, and heating under reduced pressure to obtain a recrystallized gadolinium ytterbium coordination complex; wherein the second solvent is a conventional recrystallization solvent, typically but not limitingly, the second solvent is anhydrous ether or anhydrous ethanol, and the specific amount is selected according to actual conditions.

[0027] According to the present invention, the molar ratio of the sum of the gadolinium element and the ytterbium element in the gadolinium-ytterbium coordination complex, the barium element in the barium source, and the copper element in the copper source is 1:(2-2.5):(3-3.5).

[0028] According to the present invention, the barium source is Ba(TTA)3(Phen)3.

[0029] In the present invention, TTA is 2-thenoyltrifluoroacetone, and Phen is phenyl. The use of the two ligands together makes the barium source more stable.

[0030] According to the present invention, the copper source is Cu(TTA)2.

[0031] According to the present invention, the solvent is tetrahydrofuran.

[0032] According to the present invention, the content of the solute in the solvent is 40-45 wt %.

[0033] In the present invention, the solute is the sum of all chemical substances dissolved in the solution, including gadolinium-ytterbium coordination complex, Ba(TTA)3(Phen)3 and Cu(TTA)2.

[0034] According to the present invention, the method further comprises post-processing the Gd-Yb-BcO superconducting film, and the specific steps include: subjecting the prepared Gd-Yb-BcO superconducting film to oxygen absorption annealing at 485-500° C. for 2-3 hours.

[0035] The second aspect of the present invention protects a gadolinium ytterbium barium copper oxide superconducting film prepared by the aforementioned preparation method.

[0036] The third aspect of the present invention protects the use of the aforementioned gadolinium ytterbium barium copper oxide superconducting film in cables, microwave devices, superconducting magnets, and quantum interference devices.

[0037] The technical solution of the present invention has the following advantages:

[0038] 1. The present invention provides a method for preparing a gadolinium ytterbium barium copper oxide superconducting film, wherein the preparation method comprises the following steps: S1, preparing a solution containing 2-thenoyltrifluoroacetone; S2, adding gadolinium oxide and ytterbium oxide to react with nitric acid to obtain a mixed solution containing gadolinium nitrate and ytterbium nitrate, mixing the solution obtained in S1 with the mixed solution, adding seed crystals to react, standing, separating and drying to obtain a gadolinium ytterbium coordination complex; S3, mixing the gadolinium ytterbium coordination complex obtained in S2, a barium source, a copper source and a solvent, using oxygen as an oxygen source, and growing a gadolinium ytterbium barium copper oxide superconducting film on the surface of a substrate by an organic metal chemical vapor deposition method; wherein the molar ratio of the gadolinium nitrate to the ytterbium nitrate is (0.7-0.78):(0.22-0.3). The present invention successfully constructs a double rare earth complex system with high volatility and thermal stability by optimizing the molar ratio of gadolinium nitrate to ytterbium nitrate and introducing 2-thenoyltrifluoroacetone (TTA) as a ligand. This design gives full play to the synergistic effect of gadolinium and ytterbium elements: the smaller ionic radius of ytterbium ions forms a nanocolumnar structure in the film, effectively constructing a pinning center; and the selection of TTA ligands not only significantly reduces the cost of raw materials (TTA is only 1,200 yuan / kg on the market, and THD is 2,450 yuan / kg), but also improves the thermal stability of metal organic complexes. In the preparation process, the seed-induced crystallization technology is used to greatly shorten the crystallization time and reduce production costs. At the same time, the MOCVD process is used to realize the continuous and stable gasification and transportation of organic liquid sources of Ba, Cu, Yb, and Gd metals. The pre-oxidation treatment ensures that the reaction process is controllable and has good stability. Through the composite coordination of rare earth elements, low-cost ligand substitution, and process synergistic optimization, a dual breakthrough in performance improvement and production cost control is achieved;

[0039] 2. The specific amount of seed crystals used in the present invention fully exerts the core function of inducing crystallization, and can minimize the consumption of raw materials, further reducing production costs;

[0040] 3. The present invention performs recrystallization to further improve the purity of the product, thereby improving the superconducting properties of the obtained film. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 Scanning electron microscope image of the gadolinium ytterbium barium copper oxide superconducting film of Example 1;

[0043] Figure 2Scanning electron microscope image of the gadolinium ytterbium barium copper oxide superconducting film of Example 2;

[0044] Figure 3 Scanning electron microscope image of the gadolinium ytterbium barium copper oxide superconducting film of Comparative Example 1;

[0045] Figure 4 Scanning electron microscope image of the gadolinium ytterbium barium copper oxide superconducting film of Comparative Example 2;

[0046] Figure 5 Scanning electron microscope image of the gadolinium ytterbium barium copper oxide superconducting film of Comparative Example 3. DETAILED DESCRIPTION

[0047] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0048] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0049] The thermogravimetric test was performed using a TGA thermogravimetric analyzer. The specific test method was as follows: starting from 25°C in a nitrogen environment, the temperature was raised to 550°C at 5°C / min; the change in sample mass was recorded.

[0050] The electrical performance test uses a four-probe tester. The specific test method is: four wires are led out from the surface of the sample, one group of wires receives a voltmeter, and the other group of wires receives a program-controlled DC source. The sample is immersed in liquid nitrogen to put it in a superconducting state. Under the control of the program, the DC current source passes a DC current gradually increasing from zero amperes into the sample, and at the same time the nanovoltmeter monitors the voltage on another group of wires. The current and voltage values ​​are recorded. When the sample loses superconductivity, the corresponding current value is the critical current value of the sample. Because 4mm wide samples can only be tested by instruments under 30K, 3T conditions, the value obtained by dividing the current of a 12mm wide sample at 77K, 0T by 3 is approximately the current value of a 4mm wide sample at 77K, 0T;

[0051] The lifting factor refers to the ratio of the critical current value of samples of the same size, for example, samples of 4 mm width, tested at 30K, 3T divided by the critical current value tested at 77K, 0T.

[0052] The magnetic field performance is characterized by the magnitude of the critical current of the sample tested at 30K and 3T.

[0053] The preparation method of the seed crystal is as follows: at 75° C., according to the molar ratio of gadolinium element in gadolinium nitrate to 2-thenoyltrifluoroacetone being 1:3, gadolinium nitrate and 2-thenoyltrifluoroacetone are added, and reacted in 1000 mL of methanol aqueous solution, 5 mL of benzene and 6 mL of acetonitrile for 7 hours to generate Gd(TTA)3.

[0054] Ba(TTA)3(Phen)3 and Cu(TTA)2 were purchased from Songshan Lake Materials Laboratory.

[0055] Example 1

[0056] This embodiment provides a gadolinium ytterbium barium copper oxide superconducting film, and the preparation method is as follows:

[0057] S1, adding 90 g of 2-thenoyltrifluoroacetone to 1250 mL of methanol and 1000 mL of water (the volume ratio of methanol to water is 1.25:1), heating to 80° C., and stirring continuously until the solution is clear, and adding 320 mL of 15.83 mol / L sodium hydroxide solution dropwise thereto to obtain a solution containing 4 wt % of 2-thenoyltrifluoroacetone;

[0058] S2, adding gadolinium oxide and ytterbium oxide to 30wt% nitric acid at a molar ratio of 0.78:0.22 between gadolinium element and ytterbium element, wherein the molar ratio of the sum of the elements of gadolinium element and ytterbium element to nitric acid is 1:6, to obtain a mixed solution containing gadolinium nitrate and ytterbium nitrate, reacting a solution containing 2-thenoyltrifluoroacetone with the mixed solution, wherein the molar ratio of the sum of the metal elements of the gadolinium element in the gadolinium nitrate and the ytterbium element in the ytterbium nitrate to 2-thenoyltrifluoroacetone is 1:3, and adding a theoretically calculated total nitric acid. The mass of the gadolinium ytterbium coordination complex is 0.15wt% of the seed crystals, after reacting for 4h, standing for 8.5h, separating, and vacuum drying to obtain the gadolinium ytterbium coordination complex, all the obtained gadolinium ytterbium coordination complex is put into a three-necked flask and dissolved in 4000mL of anhydrous ether, standing for 12h, filtered through K49 filter paper, the filtrate is transferred into a single-necked flask and placed in an oil bath, the vacuum pump is turned on, the temperature is adjusted to 90°C, and the solvent is evaporated by heating to obtain the recrystallized gadolinium ytterbium coordination complex;

[0059] S3, adding the recrystallized gadolinium ytterbium coordination complex, Ba(TTA)3(Phen)3, and Cu(TTA)2, wherein the molar ratio of the sum of the ytterbium element and the gadolinium element in the gadolinium ytterbium coordination complex, the barium element in the barium source, and the copper element in the copper source is 1:2:3, to tetrahydrofuran, wherein the content of the solute in the tetrahydrofuran is 42.75wt%, stirring for 4h at a speed of 60r / min, filtering, and at 750°C, vaporizing the filtrate and reacting with 99.999% pure oxygen to grow a gadolinium ytterbium barium copper oxide superconducting film on the surface of a lanthanum manganate substrate by MOCVD, and oxygen annealing at 485°C for 2h;

[0060] Scanning electron microscopy of Gd-Yb-Ba-Cu-O superconducting film Figure 1 As shown in the figure, it can be seen that the surface of the film is smooth with only a small amount of impurities; the weight loss step of the sample in the thermogravimetric test is -94.50%; at 77K, 0T, the critical current of the 12mm wide sample for electrical performance testing is 725.21A; at 30K, 3T, the critical current of the 4mm wide sample for electrical performance testing is 822.5A, and the improvement factor is 3.5.

[0061] Example 2

[0062] This embodiment provides a gadolinium ytterbium barium copper oxide superconducting film, and the preparation method is as follows:

[0063] S1, adding 90 g of 2-thenoyltrifluoroacetone to 1250 mL of methanol and 1000 mL of water (the volume ratio of methanol to water is 1.25:1), heating to 75° C., and stirring continuously until the solution is clear, and adding 320 mL of 15.83 mol / L sodium hydroxide solution dropwise thereto to obtain a solution containing 4 wt% of 2-thenoyltrifluoroacetone;

[0064] S2, adding gadolinium oxide and ytterbium oxide to 30wt% nitric acid at a molar ratio of 0.71:0.29 for gadolinium element and ytterbium element, wherein the molar ratio of the sum of the elements of gadolinium element and ytterbium element to nitric acid is 1:6, to obtain a mixed solution containing gadolinium nitrate and ytterbium nitrate, and mixing the solution containing 2-thenoyltrifluoroacetone with the mixed solution for reaction, wherein the molar ratio of the sum of the metal elements of the gadolinium element in the gadolinium nitrate and the ytterbium element in the ytterbium nitrate to 2-thenoyltrifluoroacetone is 1:3, and adding a theoretically calculated The synthesized gadolinium ytterbium coordination complex is measured by mass, and the mass of the seed crystal is 0.15wt%. After reacting for 4h, it is allowed to stand for 8.5h, separated, and vacuum dried to obtain the gadolinium ytterbium coordination complex. All the obtained gadolinium ytterbium coordination complex is put into a three-necked flask and dissolved in 4000mL of anhydrous ether. It is allowed to stand for 12h, filtered through K49 filter paper, and the filtrate is transferred to a single-necked flask and placed in an oil bath. The vacuum pump is turned on, the temperature is adjusted to 90°C, and the solvent is evaporated by heating to obtain the recrystallized gadolinium ytterbium coordination complex.

[0065] S3, adding the recrystallized gadolinium ytterbium coordination complex, Ba(TTA)3(Phen)3, and Cu(TTA)2, wherein the molar ratio of the sum of the ytterbium element and the gadolinium element in the gadolinium ytterbium coordination complex, the barium element in the barium source, and the copper element in the copper source is 1:2:3, to tetrahydrofuran, wherein the content of the solute in the tetrahydrofuran is 42.75wt%, stirring for 4 hours at a speed of 60r / min, filtering, and at 750°C, vaporizing the filtrate and reacting with 99.999% pure oxygen to grow a gadolinium ytterbium barium copper oxide superconducting film on the surface of a lanthanum manganate substrate by MOCVD, and oxygen annealing at 485°C for 2.5 hours;

[0066] Scanning electron microscopy of Gd-Yb-Ba-Cu-O superconducting film Figure 2 As shown in the figure, it can be seen that the surface of the film is relatively smooth, with a small amount of impurities, and it can still meet the needs of use; the weight loss step of the thermogravimetric test sample is -94.42%; at 77K, 0T, the critical current of the 12mm wide sample for electrical performance testing is 700.06A; at 30K, 3T, the critical current of the 4mm wide sample for electrical performance testing is 736A, and the improvement factor is 3.2.

[0067] Comparative Example 1

[0068] This comparative example provides a gadolinium barium copper oxide superconducting film, and the preparation method is as follows:

[0069] The method of Example 1 is the same as that of Example 1, except that in step S2, gadolinium oxide is added to 30wt% nitric acid, the molar ratio of gadolinium element to nitric acid is 1:6, and a gadolinium nitrate solution is obtained; a solution containing 2-thenoyltrifluoroacetone is mixed with the gadolinium nitrate solution, wherein the molar ratio of gadolinium element to 2-thenoyltrifluoroacetone in the gadolinium nitrate is 1:3, and seed crystals of the same mass as those in Example 1 are added; after reacting for 4 hours, the mixture is allowed to stand for 8.5 hours, separated, and vacuum dried to obtain a gadolinium coordination complex; all the obtained gadolinium coordination complex is charged into a three-necked flask and dissolved in 4000mL of anhydrous ether, allowed to stand for 12 hours, filtered through K49 filter paper, the filtrate is transferred into a single-necked flask and placed in an oil bath, the vacuum pump is turned on, the temperature is adjusted to 90°C, and the solvent is evaporated by heating to obtain a recrystallized gadolinium coordination complex;

[0070] Scanning electron microscopy of gadolinium barium copper oxide superconducting film Figure 3 As shown in the figure, it can be seen that the surface of the film is rough and has many impurities; the weight loss step of the sample in the thermogravimetric test is -92.53%; at 77K, 0T, the critical current of the 12mm wide sample for electrical performance testing is 477.88A; at 30K, 3T, the critical current of the 4mm wide sample for electrical performance testing is 420A, and the improvement factor is 2.8.

[0071] Comparative Example 2

[0072] This comparative example provides an ytterbium barium copper oxide superconducting film, and the preparation method is as follows:

[0073] The method of Example 1 is the same as that of Example 1, except that in step S2, ytterbium oxide is added to 30wt% nitric acid, the molar ratio of ytterbium element to nitric acid is 1:6, and ytterbium nitrate solution is obtained; the solution containing 2-thenoyltrifluoroacetone is mixed with the ytterbium nitrate solution, wherein the molar ratio of ytterbium element to 2-thenoyltrifluoroacetone in ytterbium nitrate is 1:3, and the same mass of seed crystals as in Example 1 are added; after reacting for 4h, the mixture is allowed to stand for 8.5h, separated, and vacuum dried to obtain an ytterbium coordination complex; all the obtained ytterbium coordination complex is charged into a three-necked flask and dissolved in 4000mL of anhydrous ether, allowed to stand for 12h, filtered through K49 filter paper, the filtrate is transferred into a single-necked flask and placed in an oil bath, the vacuum pump is turned on, the temperature is adjusted to 90°C, and the solvent is removed by heating and evaporation to obtain a recrystallized ytterbium coordination complex;

[0074] SEM images of YbBaCuO superconducting films Figure 4 As shown in the figure, it can be seen that the surface of the film is rough and has many impurities; the weight loss step of the sample in the thermogravimetric test is -90.87%; at 77K, 0T, the critical current of the 12mm wide sample for electrical performance testing is 415.26A; at 30K, 3T, the critical current of the 4mm wide sample for electrical performance testing is 366.6A, and the improvement factor is 2.82.

[0075] Comparative Example 3

[0076] This comparative example provides a gadolinium ytterbium barium copper oxide superconducting film, and the preparation method is as follows:

[0077] The method of Example 1 is different in that, in step S2, gadolinium oxide and ytterbium oxide are added to 30wt% nitric acid at a molar ratio of 0.68:0.32 between gadolinium element and ytterbium element, and the molar ratio of the sum of the elements of gadolinium element and ytterbium element to nitric acid is 1:6, to obtain a mixed solution containing gadolinium nitrate and ytterbium nitrate, and a solution containing 2-thenoyltrifluoroacetone is reacted with the mixed solution, wherein the molar ratio of the sum of the metal elements of the gadolinium element in the gadolinium nitrate and the ytterbium element in the ytterbium nitrate to 2-thenoyltrifluoroacetone is 1:3, and at the same time A seed crystal with a mass of 0.15 wt% based on the mass of the theoretically synthesized gadolinium ytterbium coordination complex is also added, and after reacting for 4 hours, the mixture is allowed to stand for 8.5 hours, separated, and vacuum dried to obtain a gadolinium ytterbium coordination complex. All the obtained gadolinium ytterbium coordination complex is placed in a three-necked flask and dissolved in 4000 mL of anhydrous ether, allowed to stand for 12 hours, filtered through K49 filter paper, and the filtrate is transferred to a single-necked flask and placed in an oil bath. The vacuum pump is turned on, the temperature is adjusted to 90° C., and the solvent is evaporated by heating to obtain a recrystallized gadolinium ytterbium coordination complex.

[0078] Scanning electron microscopy of Gd-Yb-Ba-Cu-O superconducting film Figure 5 As shown in the figure, it can be seen that the surface roughness of the film is relatively large and there are many impurities; the weight loss step of the sample in the thermogravimetric test is -93.61%; at 77K, 0T, the critical current of the electrical performance test of the 12mm wide sample is 613.03A; at 30K, 3T, the critical current of the electrical performance test of the 4mm wide sample is 510A, and the improvement factor is 2.5.

[0079] Comparative Example 4

[0080] This comparative example provides a gadolinium ytterbium barium copper oxide superconducting film, and the preparation method is as follows:

[0081] In the manner of Example 1, except that "tetramethylheptanone" is used to replace "2-thenoyltrifluoroacetone";

[0082] The weight loss step of the thermogravimetric test sample was -93.20%; at 77K, 0T, the critical current of the electrical performance test of the 12mm wide sample was 596A; at 30K, 3T, the critical current of the electrical performance test of the 4mm wide sample was 574A, and the improvement factor was 2.9.

[0083] The present invention achieves a dual breakthrough of performance improvement and production cost control through specific rare earth element complex coordination, low-cost ligand substitution, and process synergistic optimization.

[0084] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A method for preparing a gadolinium ytterbium barium copper oxide superconducting film, characterized in that: The preparation method comprises the following steps: S1, preparing a solution containing 2-thenoyltrifluoroacetone; S2, adding gadolinium oxide and ytterbium oxide to react with nitric acid to obtain a mixed solution containing gadolinium nitrate and ytterbium nitrate, mixing the solution obtained in S1 with the mixed solution, adding seed crystals to carry out chemical reaction, standing, separating and drying to obtain a gadolinium-ytterbium coordination complex; S3, mixing the gadolinium-ytterbium coordination complex obtained in S2, a barium source, a copper source and a solvent, and growing a gadolinium-ytterbium-barium-copper-oxygen superconducting film on the surface of the substrate by an organic metal chemical vapor deposition method using oxygen as an oxygen source; Wherein, the molar ratio of gadolinium nitrate to ytterbium nitrate is (0.7-0.78):(0.22-0.3).

2. The preparation method according to claim 1, characterized in that: In S1, the specific steps of preparing include: dissolving 2-thenoyltrifluoroacetone in a first solvent, adding a sodium hydroxide solution, and obtaining a solution containing 2-thenoyltrifluoroacetone.

3. The preparation method according to claim 2, characterized in that: The first solvent is methanol and water, and the volume ratio of methanol to water is 1.2-1.5:1; And / or, the concentration of the sodium hydroxide solution is 15-18 mol / L; And / or, the volume ratio of the first solvent to the sodium hydroxide solution is 5-8:

1.

4. The preparation method according to claim 1, characterized in that: The specific preparation steps of the seed crystal include: at 75-80° C., gadolinium nitrate and 2-thenoyltrifluoroacetone are subjected to coordination reaction to obtain the seed crystal; And / or, based on the theoretically calculated mass of the synthesized gadolinium-ytterbium coordination complex, the mass of the seed crystal is 0.1-0.2 wt %.

5. The preparation method according to claim 1, characterized in that: In S2, the reaction time is 3-6h; And / or, the standing time is 8-10 hours.

6. The preparation method according to claim 1, characterized in that: The method also includes subjecting the gadolinium ytterbium coordination complex to recrystallization, including the following steps: dissolving the gadolinium ytterbium coordination complex in a second solvent and placing the complex for 10-12 hours, filtering the complex, and heating the complex under reduced pressure to obtain the recrystallized gadolinium ytterbium coordination complex.

7. The preparation method according to claim 1, characterized in that: The molar ratio of the sum of the gadolinium element and the ytterbium element in the gadolinium-ytterbium coordination complex, the barium element in the barium source, and the copper element in the copper source is 1:(2-2.5):(3-3.5); and / or, the barium source is Ba(TTA)3(Phen)3; And / or, the copper source is Cu(TTA)2; And / or, the solvent is tetrahydrofuran; And / or, the content of solute in the solvent is 40-45wt%.

8. The preparation method according to claim 1, characterized in that: The method also includes post-processing the gadolinium ytterbium barium copper oxide superconducting film, and the specific steps include: annealing the prepared gadolinium ytterbium barium copper oxide superconducting film at 485-500° C. for 2-3 hours with oxygen absorption.

9. A gadolinium ytterbium barium copper oxide superconducting film prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the gadolinium ytterbium barium copper oxide superconducting film according to claim 9 in cables, microwave devices, superconducting magnets, and quantum interference devices.

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