The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 26, 1994
Filed:
Oct. 21, 1992
Ying Xin, Lawrence, KS (US);
Zhengzhi Sheng, Fayetteville, AR (US);
Yufang Li, Fayetteville, AR (US);
Midwest Superconductivity, Inc., Lawrence, KS (US);
The University of Arkansas, Fayetteville, AR (US);
Abstract
An improved technique for the fabrication of thallium-based superconducting oxides, and particularly Tl:Ba:Ca:Cu:O 2223 oxides, is described which allows production of very pure superconductors (>95% 2223 phase) having excellent structural characteristics. The method of the invention involves first forming a self-sustaining body of starting oxides and subjecting this body to a sintering technique wherein the temperature of the body is gradually raised to a maximum level of about 850.degree.-930.degree. C., followed by maintaining the body at this temperature for a period of about 48 hours. The body is then slowly cooled to avoid distortion and loss of superconducting character. Most preferably, the sintering is a two-stage operation, wherein the body is first heated a relatively low rate (e.g., 1.degree.-10.degree. C./min.) to a temperature of about 650.degree.-750.degree. C., followed by faster heating at a higher rate to achieve the maximum sintering temperature. Cooling is likewise staged, involving slow cooling at a rate of about O.1.degree.-5.degree. C./min. until a temperature of about 600.degree.-650.degree. C. is reached, where the body is maintained at this temperature for about 5-20 hours. Final cooling is allowed to occur naturally down to ambient temperature.