X-RAY-ABSORPTION SPECTROSCOPIC STUDIES OF THE T'-TYPE GD1.85-XPRXCE0.15CUOY SYSTEM

X-ray absorption near edge structure (XANES) studies on the T'-type Gd 1.85-xPrxCe0.15CuOy; x = 0.00, 1.10, 1.35 and 1.85 are carried out. Th e Pr L-3-, Ce L-3- and Cu K-absorption edge regions in these compounds have been measured. Pr in the reduced superconducting (SC) samples is found to be in 3+ state, while in the oxygenated non-SC samples, sign atures of both Pr3+ and Pr4+ are observed. Ce remains throughout in th e mixed (3+, 4+) valent state. As the Pr concentration (x) in the redu ced samples is increased, the unoccupied DOS, as reflected by intensit y of the white line at the Cu K-edge, decreases. This is attributed to an increase in the electron density due to the creation of oxygen vac ancies. (C) 1997 Elsevier Science B.V.