Effect of Ni Substitution for Cu in 110 K Phase of (Bi, Pb)-Sr-Ca-Cu-O Superconductors

Abstract
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(Cu1-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≤0.03 and became 90 K at x=0.03. T c remained constant at 89 K in the region of 0.03<x≤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.