Bismuth-containing superconducting material and process for producing it

US5250509A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Bernhard Hettich · Hofheim, DE
• Peter Majewski · Welzheim, DE
• Klaus Schulze · Gernrode, DE
• Gunter Petzow · Echterdingen, DE

Key dates

• Filing date: Feb 20, 1992
• Grant date: Oct 5, 1993
• Expiry date: Feb 20, 2012

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S505/782
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

The invention relates to an oxide-ceramic superconducting material which contains bismuth, strontium, calcium and copper, having an overall composition of Bi.sub.y Ca.sub.2 Sr.sub.2 Cu.sub.3 O.sub.x, where y is an integer from 2.35 to 2.6 and x is about 10 to 12. The material has a critical temperature T above 105 K and has a proportion of the phase Bi.sub.2 Sr.sub.2 Ca.sub.2 Cu.sub.3 O.sub.x of at least 85% by volume. The invention also relates to a process for producing a bismuth-containing superconducting material which comprises holding the oxides or oxide precursors of bismuth, strontium, calcium and copper at a temperature in the range from 850.degree. to 890.degree. C. over a time span of a plurality of hours and adhering to the following atomic ratios: EQU Bi:Cu>2:3 EQU Ca:Sr=0.9 to 1.50 EQU .SIGMA.(Sr+Ca):Cu=4.2:3 to 4:3.33 EQU Bi:.SIGMA.(Sr+Ca)=2.35:4 to 3.1:4