Control of YBa sub 2 Cu sub 3 O sub 7 minus x degradation during heat treatment

Conference · Mon Oct 01 00:00:00 EDT 1990

OSTI ID:6152206

Dorris, S E; Poeppel, R B; Picciolo, J J; Balachandran, U; Lanagan, M T; Zhang, C Z; Merkle, K; Gao, Y; Dusek, J T ^[1]; Jordan, H E; Schiferl, R F; Edick, J D ^[2]

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1. Argonne National Lab., IL (USA)
2. Reliance Electric Co., Cleveland, OH (USA)

The importance of closely controlling the furnace atmosphere during processing of YBa{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) was examined. The stability of YBCO during sintering was studied as a function of CO{sub 2} partial pressure in CO{sub 2}/O{sub 2} gas mixtures. The zero-field critical current density, J{sub c}, decreased with increasing CO{sub 2} partial pressure, and ultimately reached zero, even though Meissner effect measurements showed that the bulk of the samples with zero transport J{sub c} remained superconducting. Examination of the microstructure and composition of the samples by TEM, AEM, and SIMS showed the presence of BaCuO{sub 2} and BaCu{sub 2}O{sub 2} at a minority of the grain boundaries. Near other grain boundaries, where second phases were not readily evident, the structure was found to be tetragonal for several tens of nm up to the grain boundaries, whereas the grain interiors were found to be orthorhombic. At high partial pressures of CO{sub 2}, YBCO completely decomposed to BaCO{sub 3}, Y{sub 2}BaCuO{sub 5} (211), and CuO. In the firing of plastically processed superconductors, such as extruded YBCO coils, it was found that the use of reduced total pressure prevents the decomposition of YBCO. 13 refs., 5 figs., 2 tabs.

• Research Organization: Argonne National Lab., IL (USA)
• Sponsoring Organization: DOE/CE; DOE/ER; National Science Foundation (NSF)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6152206
• Report Number(s): CONF-900910-3; ON: DE91006564; CNN: DMR-8809854
• Resource Relation: Conference: 2. world congress on superconductivity, Houston, TX (USA), 10-13 Sep 1990
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BARIUM OXIDES
DECOMPOSITION
COPPER OXIDES
HIGH-TC SUPERCONDUCTORS
SINTERING
YTTRIUM OXIDES
CARBON DIOXIDE
ELECTRIC CONDUCTIVITY
GRAIN BOUNDARIES
MICROSTRUCTURE
PARTIAL PRESSURE
SUPERCONDUCTING COILS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
COPPER COMPOUNDS
CRYSTAL STRUCTURE
ELECTRICAL PROPERTIES
FABRICATION
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360201* - Ceramics
Cermets
& Refractories- Preparation & Fabrication
360202 - Ceramics
Cermets
& Refractories- Structure & Phase Studies
426001 - Engineering- Superconducting Devices & Circuits- (1990-)