The Effect of Nano Co_3O_4 Addition on Structure and Critical Temperature of Bi(Pb)‐Sr‐Ca‐Cu‐O Superconductors

摘要

The objective of this study is to investigate the effect of nano Co_3O_4 addition in Bi(Pb)‐Sr‐Ca‐Cu‐O superconductor on the critical temperature (TC), the phase formation and the microstructure. Two kinds of precursor powder were studied; one was a pure Bi(Pb)‐Sr‐Ca‐Cu‐O and the other was a mixture of Bi(Pb)‐Sr‐Ca‐Cu‐O with nano Co_3O_4 powder. The precursors were prepared by the conventional powder solid‐state reaction. 0.01 wt% to 0.04 wt% of nano‐particles of Co_3O_4 was added to the samples. Co_3O_4 act as the magnetic impurities in the superconductor system. From the results, it showed that a low concentration and appropriate amount of magnetic impurities enhanced the critical temperature of Bi(Pb)‐Sr‐Ca‐Cu‐O superconductor. The materials contained both the high T_c phase (Bi_2Sr_2Ca_2Cu_3O_X) and the low T_c phase (Bi_2Sr_2Ca_1Cu_2O_X).