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Author Guo, J. ♦ Lewis, J. A. ♦ Goretta, K. C. ♦ Schwartz, J.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword MATERIALS SCIENCE ♦ HIGH-TC SUPERCONDUCTORS ♦ SUPERCONDUCTING WIRES ♦ BISMUTH OXIDES ♦ STRONTIUM OXIDES ♦ CALCIUM OXIDES ♦ COPPER OXIDES ♦ SILVER ♦ POWDERS ♦ MICROSTRUCTURE ♦ CRITICAL CURRENT ♦ ROLLING ♦ MAGNETIZATION
Abstract Bi{sub 2}Sr{sub 2}Ca{sub 0.64}Cu{sub 1.64}O{sub {ital x}} (nominally Bi2212) powders were fabricated into powder-in-tube Ag- and Ag(7 at. % Cu)-sheathed tapes by cold and hot rolling to investigate the effects of sheath composition and rolling conditions on their microstructural development and superconducting properties. Bi2212 tapes with Ag(Cu) sheaths exhibited improved grain alignment and interfacial uniformity, as well as enhanced formation of the Bi-free phase ({approx}Sr{sub 7.5}Ca{sub 6.5}Cu{sub 14}O{sub {ital x}}), relative to the Ag-sheathed specimens. The hot-rolled Ag(Cu)-sheathed tapes displayed superior critical current densities ({ital J}{sub {ital c}}), where magnetization {ital J}{sub {ital cm}}=1.5{times}10{sup 6} ({ital H}{parallel}{ital c}) and 4.6{times}10{sup 5} A/cm{sup 2} ({ital H}{perpendicular}{ital c}) at {ital T}=5 K, {ital H}=1 T. Correspondingly, these specimens had transport critical current densities ({ital J}{sub {ital ct}}) of 6.7{times}10{sup 4} A/cm{sup 2} ({ital H}{parallel}{ital c}) and 5.4{times}10{sup 4} A/cm{sup 2} ({ital H}{perpendicular}{ital c}) at {ital T}=4.2 K, {ital H}=0 T and 2.2{times}10{sup 4} A/cm{sup 2} ({ital H}{parallel}{ital c}) and 3.0{times}10{sup 4} A/cm{sup 2} ({ital H}{perpendicular}{ital c}) at {ital T}=4.2 K, {ital H}=14 T. The chemical stability of the Ag(Cu) sheath regions during the partial melting process was also studied. Rapid oxidation of copper produced Cu{sub 2}O precipitates in the sheath at 885 {degree}C, and subsequently a Cu{sub 2}O-free zone developed near the core/sheath interface. A theoretical analysis of Cu{sub 2}O precipitate formation and decomposition during thermal processing is presented. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 1995-10-01
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 78
Issue Number 7


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