The Effect of Nano Co[sub 3]O[sub 4] Addition on Structure and Critical Temperature of Bi(Pb)-Sr-Ca-Cu-O Superconductors

The objective of this study is to investigate the effect of nano Co 3 O 4 addition in Bi(Pb)‐Sr‐Ca‐Cu‐O superconductor on the critical temperature (T C ), 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 3 O 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 3 O 4 was added to the samples. Co 3 O 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 2 Sr 2 Ca 2 Cu 3 O X ) and the low T c phase ( Bi 2 Sr 2 Ca 2 Cu 3 O X ).