The (Bi,Pb)4Sr3Ca3Cu4Ox glass–ceramics: Disordered metal and superconductor

The (Bi_0.8Pb_0.2)₄Sr₃Ca₃Cu₄O_x glass, annealed under proper conditions, is transformed into a granular metal and superconductor. Oxide superconductors of the bismuth family crystallize as a result of annealing: (Bi,Pb)₂Sr₂CuO_x (2201, T_c = 10 K), (Bi,Pb)₂Sr₂CaCu₂O_x (2212, T_c = 85 K) and (Bi,Pb)₂Sr₂Ca₂Cu₃O_x (2223, T_c = 100 K). (Bi_0.8Pb_0.2)₄Sr₃Ca₃Cu₄O_x glass–ceramic samples were obtained by annealing an amorphous solid at temperatures between 650 °C and 870 °C. The temperature dependence of resistivity in annealed samples was measured with the conventional four-terminal method in the temperature range from 3 K to 300 K. The (Bi_0.8Pb_0.2)₄Sr₃Ca₃Cu₄O_x glass–ceramics may be considered as a disordered metal and superconductor. The material has high resistivity and a high, usually negative, temperature coefficient of resistivity (TCR). Its granular and disordered character is also reflected in its superconducting properties. The normal-state and superconducting properties are correlated.