EFFECT OF NI SUBSTITUTION FOR CU IN 110-K PHASE OF (BI,PB)-SR-CA-CU-O SUPERCONDUCTORS

The effect of Ni substitution for Cu in the 110 K phase of (Bi, Pb)-Sr-Ca-Cu-O superconductor was investigated. Samples of Bi1.84Pb0.34Sr1.91Ca2.03(Cu(1-x)Ni(x))3.06O(y) were prepared. The single phase was obtained up to a Ni concentration of x = 0.015. The zero-resistance temperature T(c) decreased monotonically in the region of x less-than-or-equal-to 0.03 and became 90 K at x = 0.03. T(c) remained constant at 89 K in the region of 0.03 < x less-than-or-equal-to 0.10. Through X-ray photoelectron spectroscopy measurements, the Cu 2p core level was found to shift toward lower binding energy with the increase of x, which shows the Ni substitution for Cu.