COMPARISON OF THE EFFECT OF PROCESSING PARAMETERS AND DEGRADATION ON THE DC AND MICROWAVE PROPERTIES OF THIN-FILMS AND POLYCRYSTALLINE BULK HIGH-TC SUPERCONDUCTING MATERIALS

The sharp increase in microwave power loss (the reverse of what has previously been reported) at the transition temperature in high-T(c) superconducting systems such as YBaCu oxide (polycrystalline bulk and thin films obtained by the laser ablation technique) and BiPbSrCaCu oxide is reported. The differences between DC resistivity (rho) and the microwave power loss (related to microwave surface resistance) are analysed from the data obtained by a simultaneous measurement set-up. The influence of various parameters, such as preparation conditions, thickness and aging of the sample and the probing frequency (6-18 GHz), on the variation of microwave power loss with temperature is outlined.