Mat. Res. Bull., Vol. 27, pp. 1161-1169, 1992. Printed in the USA. 0025-5408/92 $5.00 + .00 Copyright (c) 1992 Pergamon Press Ltd. COMPLEX ELECTRICAL PERMITTIVITY OF 0-3 SUPERCONDUCTING CERAMIC/POLYMER COMPOSITES J. Unsworth, J. Du, B.J. Crosby and M. G. Stevens Centre for Materials Technology and Department of Materials Science, University of Technology, Sydney N.S.W. 2007, Australia (Received June 26, 1992; Communicated by J.B. Goodenough) ABSTRACT The dielectric behaviour of a new high Tc superconducting composite material has been investigated. The composites consist of YBa2Cu307. x superconductor powder embedded in a thermoplastic matrix. The complex electrical permittivity has been determined at frequencies between lkHz and 1MHz and temperatures between 50 and 290K for composites with volume percentage of superconductor from 0 to 70%. MATERIALS INDEX: superconductor, polymer, composites. Introduction High Tc superconducting ceramics have inherent problems of brittleness, difficulty in processing and chemical instability. Forming them into composites with polymer as a matrix has proved to be a good approach in solving these problems [1-4]. Superconducting ceramic/polymer composites have superior mechanical properties, better machinability and processing flexibility in comparison with ceramics alone. Encapsulation also protects the ceramics from environmental deterioration and oxygen loss. 0-3 type YBa2Cu307_x/ thermoplastic composites have been fabricated with a wide range of compositions. In this paper, the measurement of the complex electrical permittivity for these new composites is reported. 1161