Issues in the Processing of Cuprate Ceramic Superconductors

Abstract

A number of the important issues in the processing of dense, superconducting ceramics are addressed and illustrated with examples drawn from our studies of the processing of yttrium barium cuprate. Among the phenomena affecting the attainment of dense, fully superconducting materials are those common to the processing of other ceramics, namely, control of composition, prevention of microcracking, adequate time for the decomposition, and escape of intermediaries prior to surface densification (the so‐called “binder burn‐off” problem). Additional requirements include the necessity to ensure complete oxygenation throughout the microstructure for full volume superconductivity and the control of texture development for maximizing the attainable transport critical current density. On the basis of the processing issues described, it is concluded that the optimum microstructure is one having finescale, interconnected porosity (to ensure escape of carbonate‐like species and subsequent, rapid oxygenation) with a fine grain size (∼1 μm) to avoid microcracking. Copyright © 1989, Wiley Blackwell. All rights reserved