X-ray absorption studies of La2-x(Ba,Sr)xCuO4 superconductors.

Abstract

X-ray absorption spectroscopy has been used to study superconducting compounds with the composition La/sub 2-//sub x/(Ba,Sr)/sub x/CuO/sub 4/ for x = 0 to 0.3 X-ray absorption measurements at the Cu K edge indicate that the copper valence is 2+ for all dopant concentrations, and that the mean square relative displacements for Cu-O nearest neighbors are approximately the same for all compositions, with an average characteristic temperature of 570 +- 30 K. Measurements at the La L/sub 3/ edge suggest that the number of empty states near the Fermi energy with O 2p character increases with dopant concentration.