Nan C Chen

US Patent:

58562770, Jan 5, 1999

Filed:

Jun 3, 1996

Appl. No.:

8/657415

Inventors:

Nan Chen - Downers Grove IL
Kenneth C. Goretta - Downers Grove IL
Stephen E. Dorris - La Grange Park IL

Assignee:

Illinois Superconductor Corporation - Mt Prospect IL

International Classification:

B05D 512
B05D 302

US Classification:

505452

Abstract:

A method of manufacture of a textured layer of a high temperature superconductor on a substrate. The method involves providing an untextured high temperature superconductor material having a characteristic ambient pressure peritectic melting point, heating the superconductor to a temperature below the peritectic temperature, establishing a reduced pO. sub. 2 atmosphere below ambient pressure causing reduction of the peritectic melting point to a reduced temperature which causes melting from an exposed surface of the superconductor and raising pressure of the reduced pO. sub. 2 atmosphere to cause solidification of the molten superconductor in a textured surface layer.

US Patent:

58212019, Oct 13, 1998

Filed:

Nov 13, 1996

Appl. No.:

8/748259

Inventors:

Nan Chen - Downers Grove IL
Kenneth C. Goretta - Downers Grove IL
Michael T. Lanagan - Woodridge IL

Assignee:

The United States of America as represented by the United States
Department of Energy - Washington DC

International Classification:

C04B 35626
C04B 35645

US Classification:

505432

Abstract:

A (BiPb). sub. 2 Sr. sub. 2 Ca. sub. 2 Cu. sub. 3 O. sub. x (Bi223) superconductor with high J. sub. c, phase purity, density and mechanical strength is formed from Bi2223 powder which is synthesized from a mixture of Bi. sub. 2 O. sub. 3, PbO, SrCO. sub. 3, CaCo. sub. 3 and CuO. The mixture is milled, then dried and calcined to synthesize the Bi2223 powder with the desired phase purity. The calcination is performed by heating the dried mixture for 50 hours at 840. degree. C. The partially synthesized powder is then milled for 1-4 hours before calcining further for another 50 hours at 855. degree. C. to complete the synthesis. After calcination, the Bi2223 powder is cold pressed to a predetermined density and sinter forged under controlled temperature and time to form a Bi2223 superconductor with the desired superconducting properties.

US Patent:

54017122, Mar 28, 1995

Filed:

Sep 18, 1992

Appl. No.:

7/947324

Inventors:

Jitrenda P. Singh - Naperville IL
Roger B. Poeppel - Glen Ellyn IL
Kenneth C. Goretta - Downers Grove IL
Nan Chen - Downers Grove IL

Assignee:

University of Chicago - Chicago IL

International Classification:

H01B 1200
H01L 3912

US Classification:

505500

Abstract:

A ceramic superconductor is produced by close control of oxygen partial pressure during sintering of the material. The resulting microstructure of YBa. sub. 2 Cu. sub. 3 O. sub. x indicates that sintering kinetics are enhanced at reduced p(O. sub. 2) and that because of second phase precipitates, grain growth is prevented. The density of specimens sintered at 910. degree. C. increased from 79 to 94% theoretical when p(O. sub. 2) was decreased from 0. 1 to 0. 0001 MPa. The increase in density with decrease in p(O. sub. 2) derives from enhanced sintering kinetics, due to increased defect concentration and decreased activation energy of the rate-controlling species undergoing diffusion. Sintering at 910. degree. C resulted in a fine-grain microstructure, with an average grain size of about 4. mu. m.