SINTERING EFFECTS IN SUPERCONDUCTING FE-BASED YBCO COMPOSITES - SIMULATION OF ELECTRICAL RESISTANCES AT LOW-TEMPERATURE

Various low temperature electrical behaviours observed in sintered Fe/ YBa2Cu3O7-delta superconducting composites are briefly reported. The i nfluence of sintering temperature and Fe composition on the supercondu cting electrical properties is discussed in terms of the chemical reac tivity of Fe/YBa2Cu3O7-delta. To interpret such resistance variations, a semi-empirical approach is used: in the model the existence of supe rconducting paths in the composite depends on the fraction of Fe; the sintering processes can be described from the interface resistances wh ich vary at low temperature. A unique resistance ratio characteristic of grain surface and grain core evolutions can be defined from the mod el to interpret the macroscopic electrical observations. The good agre ement between the calculated and experimental R(T) variations allows c haracterization of the interfaces which develop during the sintering p rocess.