Magnetic and electrical properties of bismuth cuprate (2212) tin composites

HTSC-metal composites are prepared and characterized in order to optimize interface effects and switching properties. The bismuth cuprate (2212) is obtained from a sol-gel method. Tin is chosen because of its low melting temperature and vapor pressure. The composites are fabricated by mixing of the powders, then heating at various temperatures and times. For value of the (2212) volumic % higher than 70 and after a sintering process, the intergranular coupling is achieved and the transition to the superconducting state is observed in the bulk. The intra- and intergranular critical currents are determined at 5 K as function of the field and the composition. The modeling of the resistivity evolution in the range 10 to 300 k allows to interpret the composite behavior: interface effects and presence of new phases after thermal treatments, particularly a semiconducting one SnO2. (authors). 15 refs., 5 figs., 1 tab