A gadolinium ytterbium barium copper oxide superconducting film and its preparation method and application

Abstract

The present invention belongs to the field of high-temperature superconducting materials and particularly relates to a gadolinium ytterbium barium copper oxide superconducting film and a preparation method and application thereof. 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, and growing the gadolinium ytterbium barium copper oxide superconducting film on a substrate surface by an organometallic chemical vapor deposition method using 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 has good volatility and high thermal stability; the generated film has few impurities and holes, a smooth surface, and excellent electrical and magnetic field properties at low temperature and high field.

Description

Technical Field

[0001] The present invention belongs to the field of high-temperature superconducting materials, and in particular 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 current carrier in second-generation high-temperature superconductors. Improving the preparation of coated conductors with excellent superconducting properties relies not only on improvements in the metal organic chemical vapor deposition (MOCVD) process, but also on strict control of raw material quality. Currently, the chemical sources used in the MOCVD process for the preparation of ReBCO superconducting tapes both domestically and internationally are primarily Ba(THD)2, Y(THD)3, Cu(THD)3, and Zr(THD)4 (THD is tetramethylheptanone). The addition of Zr(THD)4 can generate BaZrO3 nanopillars within the ReBCO ceramic layer. This design aims to significantly enhance the current carrying capacity and anti-magnetic properties of the superconducting tape in low-temperature, high-magnetic field environments through the 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 precision 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 thin film deposition - in the MOCVD process, the volatilization inconsistency 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 deviation defects). 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 the presence of impurities, rough pores, 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] A 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, allowing to stand, 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-oxide superconducting film on the substrate surface by metal organic chemical vapor deposition 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 limited to, the mixing method is stirring, the rotation speed is 40-60 r / min, and the stirring time is 4-6 hours. 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 a 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 limiting, 1-10 mol of gadolinium oxide is reacted with 30 wt% nitric acid 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 is reacted with 30 wt% nitric acid 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 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, which 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) with NaOCH3 as the 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 subjected to a coordination reaction to obtain seed crystals, wherein the molar ratio of gadolinium element to 2-thenoyltrifluoroacetone in the gadolinium nitrate is 1:3; the specific reaction solution system can be a solution that can dissolve the reactants, typically but not limited to a methanol mixed solution, wherein 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 carried out for 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, since 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 to ytterbium 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 3-6 hours.

[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 grown 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 solvent for 10-12 hours, filtering the solvent, and heating the solvent under reduced pressure to obtain a recrystallized gadolinium-ytterbium coordination complex; wherein the second solvent is a conventional recrystallization solvent, typically but not limitingly, anhydrous ether or anhydrous ethanol, and the specific amount used is selected according to actual conditions.

[0027] According to the present invention, the molar ratio of the sum of gadolinium and ytterbium in the gadolinium-ytterbium coordination complex, the barium in the barium source, and the copper 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 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: annealing the prepared Gd-Yb-BcO superconducting film at 485-500° C. for 2-3 hours with oxygen absorption.

[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, and growing a gadolinium ytterbium barium copper oxide superconducting film on a substrate surface by metal organic chemical vapor deposition 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). The present invention successfully constructed a double rare earth complex system with high volatility and thermal stability by optimizing the molar ratio of gadolinium nitrate and ytterbium nitrate and introducing 2-thiopheneyltrifluoroacetone (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 nano-columnar 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 and THD is 2,450 yuan / kg on the market), but also improves the thermal stability of metal organic complexes. In the preparation process, the seed 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 vaporization and transportation of organic liquid phase 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 has been achieved;

[0039] 2. The specific amount of seed crystals used in the present invention fully exerts the core function of inducing crystallization, while minimizing 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 embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any 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 and are not intended to limit the best mode of implementation. They do not limit the content and scope of protection of the present invention. Any product identical or similar to the present invention obtained by anyone under the guidance of the present invention or by combining the features of the present invention with other prior arts shall fall within the scope of protection 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 this field can be used. If the manufacturer of the reagents or instruments is not specified, they are all commercially available conventional reagents.

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

[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 one group of wires receives a programmable 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 the 12mm wide sample at 77K, 0T by 3 is approximately the current value of the 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 critical current of the sample tested at 30K and 3T.

[0053] The seed crystal preparation method is as follows: at 75°C, gadolinium nitrate and 2-thiopheneyltrifluoroacetone are added in a molar ratio of gadolinium element to 2-thiopheneyltrifluoroacetone of 1:3 in gadolinium nitrate, 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 30 wt% nitric acid in a molar ratio of gadolinium element to ytterbium element of 0.78:0.22, wherein the molar ratio of the sum of the gadolinium element and ytterbium element to the nitric acid is 1:6, to obtain a mixed solution containing gadolinium nitrate and ytterbium nitrate, reacting the mixed solution with a solution containing 2-thiopheneyltrifluoroacetone, 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 the 2-thiopheneyltrifluoroacetone is 1:3, and also adding a theoretically calculated amount of nitric acid. The obtained gadolinium-ytterbium coordination complex was reacted for 4 hours, 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 was placed in a three-necked flask and dissolved in 4000 mL of anhydrous ether. The mixture was allowed to stand for 12 hours, filtered through K49 filter paper, and the filtrate was transferred to a single-necked flask and placed in an oil bath. The vacuum pump was turned on, the temperature was adjusted to 90° C., and the solvent was evaporated by heating to obtain a 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, where the solute content in the tetrahydrofuran is 42.75wt%, stirring for 4 hours at a speed of 60 r / min, filtering, and vaporizing the filtrate at 750° C. 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 annealing at 485° C. for 2 hours with oxygen absorption;

[0060] Scanning electron microscopy of Gd-Yb-Ba-CuO 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 thermogravimetric test sample is -94.50%; at 77K, 0T, the critical current of the electrical performance test of the 12mm wide sample is 725.21A; at 30K, 3T, the critical current of the electrical performance test of the 4mm wide sample 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 30 wt% nitric acid at a molar ratio of 0.71:0.29 for gadolinium and ytterbium, and the molar ratio of the sum of the gadolinium and ytterbium elements to the nitric acid is 1:6, to obtain a mixed solution containing gadolinium nitrate and ytterbium nitrate, mixing the solution containing 2-thiopheneyltrifluoroacetone 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-thiopheneyltrifluoroacetone is 1:3, and also adding a theoretically calculated amount of nitric acid. The synthesized gadolinium-ytterbium coordination complex was prepared by reacting the seed crystals at a mass of 0.15 wt % for 4 h, allowing the mixture to stand for 8.5 h, separating the seed crystals, and vacuum drying the resulting gadolinium-ytterbium coordination complex. The resulting gadolinium-ytterbium coordination complex was placed in a three-necked flask and dissolved in 4000 mL of anhydrous ether. The mixture was allowed to stand for 12 h, filtered through K49 filter paper, and the filtrate was transferred to a single-necked flask and placed in an oil bath. The vacuum pump was turned on, the temperature was adjusted to 90° C., and the solvent was evaporated by heating to obtain a 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 solute content in the tetrahydrofuran is 42.75wt%, stirring for 4 hours at a rotation speed of 60 r / min, filtering, and vaporizing the filtrate at 750° C. 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 annealing at 485° C. for 2.5 hours with oxygen absorption;

[0066] Scanning electron microscopy of Gd-Yb-Ba-CuO 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, which can still meet the needs of use; the weight loss step of the sample in the thermogravimetric test is -94.42%; at 77K, 0T, the critical current of the electrical performance test of the 12mm wide sample is 700.06A; at 30K, 3T, the critical current of the electrical performance test of the 4mm wide sample 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 30 wt % nitric acid, with a molar ratio of gadolinium element to nitric acid of 1:6, to obtain a gadolinium nitrate solution; 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 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 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 coordination complex;

[0070] Scanning electron microscopy of Gd-BaCuO superconducting film Figure 3 As shown in the figure, it can be seen that the surface of the film is rough and there are many impurities; the weight loss step of the thermogravimetric test sample 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 an ytterbium nitrate solution is obtained; the solution containing 2-thiophenecarbonyltrifluoroacetone is mixed with the ytterbium nitrate solution, wherein the molar ratio of ytterbium element to 2-thiophenecarbonyltrifluoroacetone 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 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 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 there are many impurities; the weight loss step of the thermogravimetric test sample 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 the same, except that in step S2, gadolinium oxide and ytterbium oxide are added to 30 wt% 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 gadolinium element and ytterbium element to the nitric acid is 1:6, to obtain a mixed solution containing gadolinium nitrate and ytterbium nitrate, and a solution containing 2-thiopheneyltrifluoroacetone 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 the 2-thiopheneyltrifluoroacetone is 1:3, and at the same time 0.15 wt% of seed crystals based on the theoretically synthesized gadolinium ytterbium coordination complex was also added. After reacting for 4 hours, the mixture was 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 was placed in a three-necked flask and dissolved in 4000 mL of anhydrous ether. The mixture was allowed to stand for 12 hours and filtered through K49 filter paper. The filtrate was transferred to a single-necked flask and placed in an oil bath. The vacuum pump was turned on, the temperature was adjusted to 90° C., and the solvent was evaporated by heating to obtain a recrystallized gadolinium ytterbium coordination complex.

[0078] Scanning electron microscopy of Gd-Yb-Ba-CuO 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 thermogravimetric test sample is -93.61%; at 77K, 0T, the critical current of the 12mm wide sample for electrical performance testing is 613.03A; at 30K, 3T, the critical current of the 4mm wide sample for electrical performance testing 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] The method of Example 1 is the same, except that "tetramethylheptanone" is used instead of "2-thenoyltrifluoroacetone";

[0082] The weight loss step of the thermogravimetric test sample was -93.20%; at 77K and 0T, the critical current of the electrical performance test of the 12mm wide sample was 596A; at 30K and 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 in performance improvement and production cost control through specific rare earth element composite coordination, low-cost ligand substitution, and process collaborative optimization.

[0084] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present 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 a chemical reaction, allowing to stand, 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-oxide superconducting film on the substrate surface by metal organic chemical vapor deposition 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); The specific preparation steps of the seed crystal include: at 75-80° C., gadolinium nitrate and 2-thenoyltrifluoroacetone are subjected to a coordination reaction to obtain the seed crystal; Based on the theoretical calculation of the mass of the synthesized gadolinium-ytterbium coordination complex, the mass of the seed crystal is 0.1-0.2 wt%; 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); The barium source is Ba(TTA)3(Phen)3; The copper source is Cu(TTA)2.

2. The preparation method according to claim 1, characterized in that In S1, the specific steps of the preparation include: dissolving 2-thenoyltrifluoroacetone in a first solvent, and adding a sodium hydroxide solution to obtain 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 In S2, the reaction time is 3-6 hours; And / or, the standing time is 8-10 hours.

5. The preparation method according to claim 1, characterized in that The method further includes recrystallizing the gadolinium ytterbium coordination complex, which includes 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.

6. The preparation method according to claim 1, characterized in that The solvent is tetrahydrofuran; And / or, the content of solute in the solvent is 40-45wt%.

7. The preparation method according to claim 1, characterized in that The method further 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 through oxygen absorption.

8. A gadolinium ytterbium barium copper oxide superconducting film produced by the method according to any one of claims 1 to 7.

9. Use of the gadolinium ytterbium barium copper oxide superconducting film according to claim 8 in cables, microwave devices, superconducting magnets, and quantum interference devices.

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