Improvement of superconducting characteristics of a Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 2//Ag thick film by controlling the microstructure under reduced O/sub 2/ atmosphere

Author

Hasegawa, T. ; Kobayashi, H. ; Kumakura, H. ; Togano, K.

Author_Institution

Showa Electr. Wire & Cable Co. Ltd., Kawasaki, Japan

Volume

5

Issue

2

fYear

1995

fDate

6/1/1995 12:00:00 AM

Firstpage

1845

Lastpage

1848

Abstract

The partial melting and slow cooling heat-treatment for a Bi-2212 thick film was carried out in 7% and 1% oxygen partial pressure. In 1% O/sub 2/ atmosphere, the partial melting point lowered below 850/spl deg/C. When cooling under 1% O/sub 2/, large Bi-free phases which were observed in samples heat-treated in air disappeared, resulting in the formation of this phase on the surface. Reduction of Ca and Cu concentration from stoichiometric composition is also effective to suppress the formation of Bi-free phases. The highest J/sub c/ value of 1.13/spl times/10/sup 5/ A/cm/sup 2/ at 4.2K in 4 T was obtained in a sample with the composition of Bi/sub 2.0/Sr/sub 2.2/Ca/sub 0.8/Cu/sub 1.9/O/sub x/ prepared in 1% O/sub 2/.<>

Keywords

bismuth compounds; calcium compounds; cooling; critical current density (superconductivity); crystal microstructure; heat treatment; high-temperature superconductors; melting point; silver; stoichiometry; strontium compounds; superconducting thin films; thick films; 4 T; 4.2 K; 850 C; Bi-2212 thick film; Bi-free phases suppression; Bi/sub 2.0/Sr/sub 2.2/Ca/sub 0.8/Cu/sub 1.9/O; Bi/sub 2.0/Sr/sub 2.2/Ca/sub 0.8/Cu/sub 1.9/O/sub x/; Bi/sub 2/Sr/sub 2/CaCu/sub 2/O-Ag; Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 2//Ag thick film; O/sub 2/; critical current density; high temperature superconductors; microstructure control; partial melting point; reduced O/sub 2/ atmosphere; slow cooling heat-treatment; stoichiometric composition; superconducting characteristics; surface; Atmosphere; Bismuth; Cooling; High temperature superconductors; Microstructure; Petroleum; Strontium; Temperature control; Wire; X-ray diffraction;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.402940

Filename

402940