FABRICATION AND CHARACTERIZATION OF YBA2CU3O7-X SN COMPOSITE SUPERCONDUCTORS .3. SINTERING AT HIGH-TEMPERATURE/

YBa2Cu3O7-x/Sn composites containing 5, 10, 1 5, and 20 wt% Sn were pr epared by conventional powder metallurgy and pressureless sintering at 950-degrees-C. Sn caused degradation of the ceramic superconductor by its chemical reaction with Ba, whose extent increased with Sn content . Composites with between 5 and 1 0 wt % Sn preserved their supercondu cting critical temperature, T(c), those with higher Sn content exhibit ed non-zero residual resistivity at low temperatures. Room-temperature resistivity and its thermal coefficient also increased with Sn conten t. The brittle behaviour of the composites is attributed to oxidation of Sn during sintering.