Ag/(Bi, Pb)-Sr-Ca-Cu-O superconducting tape processing: Solid state chemistry aspects

1993

Abstract Different preparation methods have been used to obtain starting powders used in the fabrication of composite tapes by the powder-in-tube method. The effect of these distinct starting powders on the superconducting properties of Ag/Bi-Sr-Ca-Cu-O monofilament tapes has been investigated. The changes in the physical properties, including the critical current density at 77 K and ac magnetic susceptibility, and microstructure, using optical and electronic microscopy, have been analyzed in relation to the solid state reactions involved in the Bi 2 Sr 2 CaCu 2 O 8+δ and Bi 2 Sr 2 Ca 2 Cu 3 O 10+δ phase transformations.

Polymer solution processing of (Bi, Pb)SrCaCuO

1991

Abstract A simple polymer processing route to the 110 K phase (Bi, Pb) 2 Sr 2 Ca 2 Cu 3 O 10+δ superconductor has been developed. The influence of the polymer to metal starting ratio, as well as the sintering temperature and time on the quality of the resulting superconducting powders has been studied by XRD, a.c. susceptibility and resistivity measurements. Microstructure of ceramic compacts has been studied by SEM, and qualitatively analysed by EDS for compositional homogeneity. The results indicate that the polymer synthesis route described here may offer a good alternative to the conventional solid state preparation methods towards attaining homogeneous 110 K superconductor powder withi…

Transport and Diamagnetic Properties of 2:2:1:2 and 2:2:2:3 (Bi-Pb)-Sr-Ca-Cu-O Superconducting Materials

1989

AbstractBismuth superconducting oriented fibers of the compositions 2:2:1:2: and 2:2:2:3 have been grown by the Laser Floating Zone (LFZ) method. Growth conditions have been optimized in order to improve the superconducting properties. The 108 K onset in susceptibility measurements (associated to the 2:2:2:3 phase) only appears well defined when starting from Sr-defective precursors.

LFZ growth of (Bi, Pb)–Sr–Ca–Cu–O superconducting fibers

1991

Powder x-ray diffraction, d.c. and a.c. susceptibilities, and SEM have been used to study (Bi1−xPbx)2Sr2Ca2Cu3O10−δ fibers grown by the Laser Floating Zone method. The well-oriented, long-grained superconductor fiber properties are shown to be highly dependent on the partial pressure of oxygen in the growth atmosphere, as well as on fiber pulling rate. Slowly grown fibers contain initially the 2212 (80 K) phase; the 2223 (110 K) phase also appears upon annealing in air. Faster growth rates result in fibers that contain a mixture of the 2212 and 2201 phases and, in this case, long annealing procedures are necessary to observe the 2223 phase.

(Bi,Pb)2Sr2Ca2Cu3O10+δ superconductor composites: Ceramics vs. fibers

1991

Abstract Well characterized (Bi, Pb) 2 Sr 2 Ca 2 Cu 3 O 10+δ superconductor powder has been used to prepare superconductor-glass, -metal and -alloy composites through solid state reaction method. A recently developed Laser Floating Zone (LFZ) apparatus has been used to transform the ceramic precursors into oriented fibers. The diamagnetic properties have been studied by a.c. susceptibility. The microstructure of fibers has been studied by SEM and compared with that of the original ceramic precursors. XRD has been used to study phase composition on representative composite samples and fibers. The results indicate some potential for the 2223-Ag composite, which displays improved diamagnetic p…

Laser floating zone growth of textured Ag/(Bi,Pb)SrCaCuO superconductors

1992

Crystal structure and magnetism of Co(HPO3)⋅H2O : A novel layered compound of Co(II)

1990

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