Interaction of Cu 3d and O 2p states in Mg1-xCuxO solid solutions with NaCl structure: X-ray photoelectron and x-ray emission study

Abstract

The electronic structure of the solid solutions Mg1-xCuxO (x= 0.10,0.12,0.1 5,0.20) with the NaCl structure was studied by means of x-ray photoelectron and soft-x-ray emission spectroscopy (XES). The XES measurements include a study of the fluorescence O K alpha spectra measured at the photon excitation energy of 550 eV and the electron-excited Cu Lcr spectra. Based on the analysis of the valence-band spectra, the partial Cu 3d states and the partial O 2p states in the O 2p-Cu 3d(4sp) bond are separated. The distribution of the partial Cu 3d states in Mg1-xCuxO is similar to that in CuO. The partial O 2p states in the O 2p-Cu 3d(4sp) bond in Mg1-xCuxO correspond essentially to the O 2p states in CuO. That means that the Cu-O interactions practically do not depend on the difference in the crystal structures of Mg1-xCuxO and CuO, but are mainly determined by electronic characteristics of atoms. The exchange splitting in the Cu 3s photoemission spectrum is analyzed. It was established that the degree of covalency and the occupancy of Cu 3d states in Mg1-xCuxO solid solutions are less than those in CuO.