X-RAY PHOTOELECTRON SPECTROSCOPIES OF NI-DOPED BI-2212 COMPOUNDS

Samples with the nominal composition Bi2Sr2Ca1Cu2-xNixO8+delta (x = 0. 00, 0.02, 0.10, 0.20) have been studied by X-ray photoelectron spectro scopy (XPS). From deconvolution of Bi 4f and O 1s XPS core-level spect ra, we propose that the main reason leading to the decrease of superco nducting transition temperature (T-c) with increasing Ni content, is t he distortion of the Bi-2212 crystal structure by extra oxygen being i ntercalated between the adjacent Bi-O layers which then affects the ho le concentration (n(h)) of the CuO2 planes. (C) 1998 Elsevier Science B.V. All rights reserved.