X-ray absorption spectroscopic studies of the T′-type Gd1.85−xPrxCe0.15CuOy system

Abstract X-ray absorption near edge structure (XANES) studies of the T′-type Gd 1.85− x Pr x Ce 0.15 CuO y ; x = 0.00, 1.10, 1.35 and 1.85 are carried out. The PrL 3 − , Ce L 3 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, signatures of both Pr 3+ and Pr 4+ are observed. Ce remains throughout in the mixed (3+, 4+) valent state. As the Pr concentration ( x ) in the reduced samples is increased, the unoccupied DOS, as reflected by intensity 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 vacancies.