Spray pyrolysis process for preparing superconductive films

• US 5,021,399 A
• Filed: 03/10/1989
• Issued: 06/04/1991
• Est. Priority Date: 03/10/1989
• Status: Expired due to Fees

• Current Assignee: Microelectronics and Computer Technology Corporation
• Original Assignee: Microelectronics and Computer Technology Corporation
• Inventors: Hsu, Hsyh-Min, Yee, Ian Y. K.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/322,454
• Time in Patent Office: 816 Days
• Field of Search: 505/1, 505/729, 505/733, 505/737, 505/739, 505/742, 427/62, 427/226, 427/314, 427/372.2, 427/375, 427/376.1, 427/376.2
• US Class Current: 505/452
• CPC Class Codes: C04B 35/04 based on magnesium oxide
• CPC Class Codes: C04B 35/08 based on beryllium oxide
• CPC Class Codes: C04B 41/0072 Heat treatment
• CPC Class Codes: C04B 41/009 characterised by the material treated
• CPC Class Codes: C04B 41/4535 applied as a solution, emulsion, dispersion or suspension
• CPC Class Codes: C04B 41/4554 the coating or impregnating material being an organic or organo-metallic precursor of an inorganic material
• CPC Class Codes: C04B 41/5009 containing nitrogen in the anion, e.g. nitrites
• CPC Class Codes: C04B 41/5016 Acids
• CPC Class Codes: C04B 41/5018 with fluorine compounds
• CPC Class Codes: C04B 41/5074 Copper oxide or solid solutions thereof CuO-Cu eutectic C04B41/5127
• CPC Class Codes: C04B 41/85 with inorganic materials
• CPC Class Codes: C23C 16/408 of copper or solid solutions thereof
• CPC Class Codes: C23C 16/56 After-treatment
• CPC Class Codes: H10N 60/0324 from a solution
• CPC Class Codes: Y10S 505/737 From inorganic salt precursors, e.g. nitrates
• CPC Class Codes: Y10S 505/742 Annealing

Abstract

An improved method for preparing high temperature Bi-Sr-Ca-Cu-O superconductive films utilizing spray pyrolysis. The method can further include an additional annealing step to improve the electrical transport properties.

Claims

1. A spray pyrolysis method for preparing thin superconductive film, comprising the steps of:

(a) preparing a spray pyrolysis solution comprising Bi,Sr,Ca and Cu metals in a solvent;

(b) heating a substrate to a first temperature;

(c) spraying said solution onto said heated substrate to form a film thereon;

(d) heating said film and substrate to a second temperature of about 700°

-825°

C., said second temperature being higher than said first temperature;

(e) heating said film and substrate to a third temperature of about 870°

-890°

C. to melt said film;

(f) once said film and substrate reach said third temperature, further heat treating said film and substrate at a fourth temperature of about 840°

-860°

C.; and

(g) cooling said film and substrate to ambient temperature.

2. A method as claimed in claim 1, wherein said first temperature is about 400°

-600°

C.

3. A method as claimed in claim 2, wherein said first temperature is about 600°

C.

4. A method as claimed in claim 1, wherein said second temperature is about 800°

C.

5. A method as claimed in claim 1, wherein said third temperature is about 880°

C.

6. A method as claimed in claim 1, wherein said heating step (e) includes heating in an apparatus set at a temperature between about 900°

-1000°

C.

7. A method as claimed in claim 6, wherein said apparatus temperature is about 950°

C.

8. A method as claimed in claim 1, wherein said fourth temperature is about 855°

C.

9. A method as claimed in claim 1, wherein said Bi:

Sr;

Ca;

Cu stoichiometry is about 2;

2;

1;

2.

10. A method as claimed in claim 1, wherein said Bi:

Sr;

Ca;

Cu stoichiometry is about 4;

3;

3;

4.

11. A method as claimed in claim 1, wherein said solvent is nitric acid.

12. A method as claimed in claim 1, wherein the thickness of said film is about 2 to 6 microns.

19. A method as claimed in claim 1, comprising the further step of (h) annealing said film and substrate in an inert gas of about 600°

-700°

C.

20. A method as claimed in claim 19, wherein said annealing temperature is about 700°

C.

13. A spray pyrolysis method for preparing thin superconductive films, comprising the steps of:

(a) preparing a spray pyrolysis solution comprising Bi, Sr, Ca and Cu metals and a fluxing agent in a solvent;

(b) heating a substrate to a first temperature;

(c) spraying said solution onto said heated substrate to form a film thereon;

(d) heating said film and substrate to a second temperature of about 700°

-825°

C., said second temperature being higher than said first temperature;

(e) heating said film and substrate at a third temperature of about 840°

-860°

C.; and

(f) cooling said film and substrate to ambient temperature.

14. A method as claimed in claim 13, wherein said fluxing agent is selected from the group consisting of sodium nitrate and potassium fluoride.

15. A method as claimed in claim 13, wherein said fluxing agent is added in an amount equal to about one-tenth of the total metal ion concentration of said Bi, Sr, Ca and Cu.

16. A method as claimed in claim 13, wherein said first temperature is about 400°

-600°

C.

17. A method as claimed in claim 13, wherein said second temperature is about 800°

C.

18. A method as claimed in claim 13, wherein said third temperature is about 850°

C.

21. A method as claimed in claim 13, comprising the further step of (g) annealing said film and substrate in an inert gas at about 600°

-700°

C.

22. A method as claimed in claim 21, wherein said annealing temperature is about 700°

C.

23. A spray pyrolysis method for preparing thin superconductive films, comprising the steps of:

spraying a spray pyrolysis solution comprising Bi, Sr, Ca and Cu metals in a solvent onto a heated substrate to form a film thereon; and

heating said film and substrate to melt said film.