Ag-sheathed Bi2Sr2CaCu2Ox round wires having 37 and 259 filaments, with filament diameters ranging from 11 to 100 μm, were fabricated by the oxide-powder-in-tube method. They were heat treated using step-solidification melt processing in air and pure O2. The transport critical current density was highest in wires processed in pure O2. It increased with decreasing filament diameter and was highest [165 000 A/cm2 (4.2 K, O T)] in wires with 11 μm filaments processed in O2.

Two different types of defect structures have been identified to be responsible for the enhanced pinning in Metal Organic Deposited YBCO films. Rare earth additions result in the formation of nanodots in the YBCO matrix, which form uncorrelated pinning centers, increasing pinning in all magnetic field orientations. 124-type intergrowths, which form as laminar structures parallel to the -plane, are responsible for the large current enhancement when the magnetic field is oriented in the -plane. TEM studies showed that the intergrowths emanate from cuprous containing secondary phase particles, whose density is partially controlled by the rare earth doping level. Critical process parameters have been identified to control this phase formation, and therefore, control the 124 intergrowth formation. This work has shown that through process control and proper conductor design, either by adjusting the composition or by multiple coatings of different functional layers, the desired angular dependence can be achieved.

A bstract--Round multlfllament Bi2Sr2Ca l C u 2 0 x In this paper we describe further the micmsmcture and Jc superconducting. Thus, 2212 is well-suited to use the process developed for fabricating Nb3Sn. In addition, because the melt processing for 2212 is relatively short and the fabrication steps are straightforward, conductor made by Ag-sheathed (Bi,Pb)2Sr2Ca2CugOx (2223) and this process is expected to be less expensive than conductor made using the more complicated 2223 process.

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