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Near-Melt Processing on High Temperature Superconducting Ceramics

IP.com Disclosure Number: IPCOM000037904D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-30
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Engler, EM: AUTHOR [+3]

Abstract

A method is described for preparing high density ceramic superconductors based on compounds such as La-xMxCuO4-y (where M=Ca,Sr,Ba); M, Ba2Cu3O7 (where M=Y or rare earth); BiSrBaCuxOy (where x=1,2,3); or TlCaBaCuxOy (where x=1,2,3,4,5) which display superior critical currents and magnetic field tolerance than those prepared by conventional ceramic processing techniques.

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Near-Melt Processing on High Temperature Superconducting Ceramics

A method is described for preparing high density ceramic superconductors based on compounds such as La-xMxCuO4-y (where M=Ca,Sr,Ba); M, Ba2Cu3O7 (where M=Y or rare earth); BiSrBaCuxOy (where x=1,2,3); or TlCaBaCuxOy (where x=1,2,3,4,5) which display superior critical currents and magnetic field tolerance than those prepared by conventional ceramic processing techniques.

The basic processing steps are described by example below for Y1Ba2Cu3O7: 1. Start with performed and highly single phase Y1Ba2Cu3O7 .

Using the unreacted starting oxide precursors results in minor unreacted or by-product phases (e.g., CuO, BaCuO2) which affect the quality of the final sample. 2. Near-melt processing in a narrow and well-defined temperature range under flowing oxygen.

Y1Ba2Cu3O7 decomposes on melting at 1010oC, giving off oxygen and phase separating into several components. In the current procedure the sample was heated just below melting point. Near-melt anneals are carried out at 1000 + 5oC in flowing oxygen for 2-36 hours. Samples heated for 36 hours are 98% dense while those heated for 2 hours are 94% dense. 3. A programmed lowering of the temperature in an oxygen atmosphere.

This involves a 900oC post-anneal (24 hours) to fully oxygenate grain contacts. This is followed by slow cooling (20-100oC/hour) to 500oC for another post-anneal for 10-20 hours, and finally continued slow cooling to room temperature.

Sampl...