The formation of superconducting phases in Bi(Pb)-Sr-Ca-Cu oxide/Ag microcomposites produced by oxidation of metallic precursor alloys

Journal Article · Thu Nov 01 00:00:00 EST 1990 · Journal of Materials Research; (USA)

DOI:https://doi.org/10.1557/JMR.1990.2633· OSTI ID:6288156

Gao, W; Li, S; Parrella, R; Rudman, D A; Vander Sande, J B ^[1]

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1. Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (USA)

Metallic alloy ribbons of Bi-Sr-Ca-Cu with nominal compositions of 2-2-1-2, 2-2-2-3, 2-2-2-4, and 2-2-3-4, with or without Pb, were made by vacuum induction melting followed by melt-spinning. Ag, at the level of 20--80 wt. %, was added to aid in the alloy melting and metallic ribbon formation processes. These ribbons were then subjected to a controlled atmosphere oxidation and annealing to produce superconducting oxide/silver microcomposites. Among the four alloy groups investigated in the present work, 2-2-3-4 alloys with 0.6 Bi replaced by Pb possess the best superconducting properties after suitable treatment. These specimens exhibited zero resistance at {ital T}=104--110 K and a critical current density of 600 A/cm{sup 2} at 77 K in zero field with excellent reproducibility. The annealing conditions, namely the annealing temperature, time and atmosphere, are discussed in terms of the formation kinetics of the superconducting phases. While the 85 K {ital T}{sub {ital c}} 2212'' phase formed over a wide temperature range (740 to 845 C) after a {similar to}2 hour anneal, the 110 K high-{Tc} transition only appeared after a {similar to}10 hour anneal at 810--840 C, suggesting that the 2223'' phase grew from the 2212'' phase controlled by diffusion. The microstructures of these superconducting microcomposites were observed and analyzed by a combination of optical and scanning electron microscopy, x-ray powder diffraction and electron probe microanalysis. The high {ital T}{sub {ital c}} 2223'' phase exhibited plate-like grains which were distributed randomly in orientation. The silver addition improved the mechanical properties of the metallic precursor ribbons and the superconducting microcomposites, promoted the formation of the 2223'' phase, and influenced the oxidation and the annealing conditions.

• DOE Contract Number: FG02-85ER45179
• OSTI ID: 6288156
• Journal Information: Journal of Materials Research; (USA), Vol. 5:11; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BISMUTH OXIDES
SUPERCONDUCTIVITY
CALCIUM OXIDES
COPPER OXIDES
LEAD OXIDES
SILVER ALLOYS
STRONTIUM OXIDES
SUPERCONDUCTING COMPOSITES
ALLOYS
ANNEALING
CRITICAL CURRENT
HIGH-TC SUPERCONDUCTORS
MICROSTRUCTURE
OXIDATION
PRECURSOR
TEMPERATURE DEPENDENCE
ALKALINE EARTH METAL COMPOUNDS
BISMUTH COMPOUNDS
CALCIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
COMPOSITE MATERIALS
COPPER COMPOUNDS
CRYSTAL STRUCTURE
CURRENTS
ELECTRIC CONDUCTIVITY
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
HEAT TREATMENTS
LEAD COMPOUNDS
MATERIALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
STRONTIUM COMPOUNDS
SUPERCONDUCTORS
TRANSITION ELEMENT COMPOUNDS
360603* - Materials- Properties
360601 - Other Materials- Preparation & Manufacture
360604 - Materials- Corrosion
Erosion
& Degradation