XPS STUDY OF T-C DEPRESSION AND M-I TRANSITION IN BI2SR2CA1-XPRXCU2OYSYSTEM

X-ray photoelectron spectroscopy (XPS) studies have been performed to explore the effect of mixed valent(3 + /4 +)Pr substitution for the di valent Ca on the electronic and crystal structure of the Bi-based cupr ates. Metal-insulator transition is observed on a well-characterized P r-doped Bi2Sr2Ca1-xPrxCu2Oy, system with different Pr concentrations ( x = 0 to 0.5). Core-level shifts of the Pi, Sr, and Ca to higher bindi ng energies are observed with increase in Pr content. XPS core-level s pectra of Sr, 3d and Ca 2p show that Pr occupies both the Sr and Ca si tes in the structure. The deconvolution of Cu 2p main peak shows a dec rease in the intensity of the higher binding energy shoulder which imp lies a decrease in Cu valence due to the hole filling caused by the ex tra electrons from Pr. (C) 1998 Elsevier Science Ltd. All rights reser ved.