Steven H Lawrence

US Patent:

60515341, Apr 18, 2000

Filed:

Apr 21, 1993

Appl. No.:

8/050787

Inventors:

Roy Rayne - New Carrollton MD
Louis E. Toth - Washington DC
Barry A. Bender - Alexandria VA
Steven H. Lawrence - Fort Washington MD

Assignee:

The United States of America as represented by the Secretary of the Navy - Washington DC

International Classification:

H01L 3900

US Classification:

505491

Abstract:

A process for producing the 2223 phase of (Pb,Bi)SrCaCuO that is much faster than existing processes has the steps of: calcining a precursor powder mixture while maintaining intimate mixing of this precursor mixture by intermediate grindings during calcination; compressing the calcination product into a consolidated body; and heating the calcination product while maintaining intimate mixing of the calcination product, to form essentially phase pure 2223 (Pb,Bi)SrCaCu). A fast process for making a (Pb,Bi)SrCaCuO part with a high J. sub. c has the steps of: pressing calcined and reacted (Pb,Bi)SrCaCuO powder into a green body having the shaped of the part; and sintering the green body for a selected time, most preferably between 6 and 8 hours, that is long enough to establish superconducting electrical contact between grains of (Pb,Bi)SrCaCuO but short enough to prevent void formation or part shape distortion. The part made by this process has a high density, at least about 4 or 5 g/cm. sup. 3.

US Patent:

51068290, Apr 21, 1992

Filed:

Sep 19, 1990

Appl. No.:

7/587466

Inventors:

Syed B. Quadri - Alexandria VA
Louis E. Toth - Washington DC
Michael S. Osofsky - College Park MD
Steven H. Lawrence - Fort Washington MD
Donald U. Gubser - Fairfax VA
Stuart A. Wolf - Bowie MD

Assignee:

The United States of America as represented by the Secretary of the Navy - Washington DC

International Classification:

H01B 1200

US Classification:

505 1

Abstract:

A substantially single phase superconducting composition is formed from a of 1:2:3 molar ratio of fine powders of a superconducting rare earth oxide, CuO, and BaCo. sub. 3. The mixed powders and shaped articles formed from the mixed powders are calcined, sintered, and cooled in an oxygen containing atmosphere. The cooling step is done slowly to convert the sample to the orthorhombic structure and to improve the superconducting properties. The article formed is a substantially single phase superconducting composition.