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CN-121983385-A - Tl-series superconducting film and preparation method thereof

CN121983385ACN 121983385 ACN121983385 ACN 121983385ACN-121983385-A

Abstract

The invention provides a Tl-series superconducting film and a preparation method thereof, and belongs to the field of superconducting film materials. The preparation method of the Tl-series superconducting film comprises the steps of mixing nitrate or acetate of metal, ethylenediamine tetraacetic acid, a water-soluble high polymer and water to obtain precursor sol, wherein the metal is thallium, barium, calcium and copper, the ratio of the thallium, the barium, the calcium, the copper to the ethylenediamine tetraacetic acid is (2-3): 2:1:2 (7-8), coating the precursor sol on a substrate to obtain the precursor film, and performing heat treatment on the precursor film under a closed condition in an oxygen atmosphere to obtain the Tl-series superconducting film. The Tl-series superconducting film obtained by the preparation method provided by the invention presents Tl-2212 phase, no impurity phase is generated, the critical transition temperature can reach 100K, and the critical transition temperature is close to the theoretical superconducting transition temperature of Tl-2212.

Inventors

  • JI LU
  • CHEN JIHUANG
  • CUI DONGXU
  • CHEN TIANJIAN
  • ZHANG ZHIHE
  • HE MING

Assignees

  • 南开大学

Dates

Publication Date
20260505
Application Date
20260402

Claims (10)

  1. 1. A preparation method of Tl-series superconducting thin film comprises the following steps: (1) Mixing nitrate or acetate of metal, ethylenediamine tetraacetic acid, a water-soluble high polymer and water to obtain precursor sol, wherein the metal is thallium, barium, calcium and copper, and the mass ratio of the thallium, the barium, the calcium, the copper and the ethylenediamine tetraacetic acid is (2-3): 2:1:2 (7-8); (2) Coating the precursor sol obtained in the step (1) on a substrate to obtain a precursor film; (3) And (3) carrying out heat treatment on the precursor film obtained in the step (2) under the airtight condition in an oxygen atmosphere to obtain the Tl-series superconducting film.
  2. 2. The method according to claim 1, wherein the water-soluble high molecular polymer in the step (1) is polyethyleneimine or polyvinyl alcohol.
  3. 3. The preparation method of claim 2, wherein the mass ratio of the water-soluble high molecular polymer to the ethylenediamine tetraacetic acid in the step (1) is 1 (0.8-1.2).
  4. 4. A method according to claim 3, wherein the mixing in step (1) is: Firstly mixing nitrate or acetate of metal with part of water to obtain a first solution; sequentially dissolving a water-soluble high polymer and ethylenediamine tetraacetic acid in the residual water for second mixing to obtain a second solution; and thirdly mixing the first solution and the second solution.
  5. 5. The method according to claim 4, wherein the concentration of calcium ions in the first solution is 0.2 to 0.3mol/L.
  6. 6. The method according to claim 4, wherein the concentration of ethylenediamine tetraacetic acid in the second solution is 0.3 to 0.35mol/L.
  7. 7. The method according to claim 1, wherein the precursor film in the step (2) has a thickness of 0.1 to 1 μm.
  8. 8. The method according to claim 1, wherein the heat treatment in the step (3) is a stepwise heat treatment.
  9. 9. The method according to claim 8, wherein the stepwise heat treatment is performed by first heating to a first heat treatment temperature at a first heating rate to perform a first heat preservation, and then heating to a second heat treatment temperature at a second heating rate to perform a second heat preservation; the first heating rate is 2-3 ℃ per minute; The first heat treatment temperature is 500-550 ℃; the first heat preservation time is 30-90 min; The second heating rate is 6-8 ℃ per minute; the second heat treatment temperature is 760-800 ℃; And the second heat preservation time is 20-60 min.
  10. 10. The Tl-series superconducting film prepared by the preparation method of any one of claims 1 to 9.

Description

Tl-series superconducting film and preparation method thereof Technical Field The invention relates to the field of superconducting thin film materials, in particular to a Tl-series superconducting thin film and a preparation method thereof. Background Tl series superconducting films, such as Tl 2Ba2CaCu2O8 (Tl-2212) superconducting films, have excellent electromagnetic properties such as high critical transition temperature (Tc is more than 105K), high critical current density, extremely low microwave surface resistance and the like, and have strong structural stability in the atmosphere environment, and the Tl series superconducting films have unique advantages in the fields of superconducting microwave devices, superconducting quantum interference devices and the like. The Tl-2212 superconducting film is prepared by adopting physical methods such as magnetron sputtering, laser pulse deposition and the like, and the methods need complicated and expensive vacuum equipment, have high production cost and low production efficiency, and are difficult to realize large-scale industrial production. However, once the hydrolysis reaction is difficult to stop in the presence of water and alcohols, the aging effect of gel is caused, so that the film structure and physical properties are difficult to control and stable, the performance (critical transition temperature) of the Tl-2212 superconducting film is limited, the complexing agent used for preparing the sol in the chemical deposition method in the prior art is a composite complexing agent, thallium element volatilized in the heat treatment process is complemented by roasting palladium with thallium source when the Tl-2212 superconducting film is prepared, and the preparation method is complex. Disclosure of Invention The invention aims to provide a Tl-series superconducting film and a preparation method thereof. The preparation method provided by the invention is simple, and the prepared Tl-series (Tl-2212) superconducting film has good crystal form, the critical transition temperature can reach 100K, and the critical transition temperature is close to the Tl-2212 theoretical superconducting transition temperature. In order to achieve the above object, the present invention provides the following technical solutions: the invention provides a preparation method of a Tl-series superconducting film, which comprises the following steps: (1) Mixing nitrate or acetate of metal, ethylenediamine tetraacetic acid, a water-soluble high polymer and water to obtain precursor sol, wherein the metal is thallium, barium, calcium and copper, and the mass ratio of the thallium, the barium, the calcium, the copper and the ethylenediamine tetraacetic acid is (2-3): 2:1:2 (7-8); (2) Coating the precursor sol obtained in the step (1) on a substrate to obtain a precursor film; (3) And (3) carrying out heat treatment on the precursor film obtained in the step (2) under the airtight condition in an oxygen atmosphere to obtain the Tl-series superconducting film. Preferably, the water-soluble high molecular polymer in the step (1) is polyethyleneimine or polyvinyl alcohol. Preferably, the mass ratio of the water-soluble high molecular polymer to the ethylenediamine tetraacetic acid in the step (1) is 1 (0.8-1.2). Preferably, in the step (1), the steps are mixed as follows: Firstly mixing nitrate or acetate of metal with part of water to obtain a first solution; sequentially dissolving a water-soluble high polymer and ethylenediamine tetraacetic acid in the residual water for second mixing to obtain a second solution; and thirdly mixing the first solution and the second solution. Preferably, the concentration of calcium ions in the first solution is 0.2-0.3 mol/L. Preferably, the concentration of the ethylenediamine tetraacetic acid in the second solution is 0.3-0.35 mol/L. Preferably, the thickness of the precursor film in the step (2) is 0.1-1 μm. Preferably, the heat treatment in the step (3) is a sectional heat treatment. Preferably, the sectional heat treatment is that the first heat preservation is carried out by raising the temperature to the first heat treatment temperature at a first heating rate, and then the second heat preservation is carried out by raising the temperature to the second heat treatment temperature at a second heating rate; the first heating rate is 2-3 ℃ per minute; The first heat treatment temperature is 500-550 ℃; the first heat preservation time is 30-90 min; The second heating rate is 6-8 ℃ per minute; the second heat treatment temperature is 760-800 ℃; And the second heat preservation time is 20-60 min. The invention also provides the Tl-series superconducting film prepared by the preparation method. The invention provides a preparation method of a Tl-series superconducting film, which comprises the following steps of (1) mixing nitrate or acetate of metal, ethylenediamine tetraacetic acid, a water-soluble high polymer and water to obtain precursor sol, wh