Soft-x-ray emission and the local p-type partial density of electronic states in Y2O3: Experiment and theory.

Photon-excited yttrium {ital M}{sub IV,V}, and electron-excited oxygen {ital K} x-ray emission spectra for yttrium oxide are presented. It is shown that, as in the case of yttrium metal, the decay of {ital M}{sub IV} vacancies does not contribute substantially to the oxide {ital M}{sub IV,V} emission. The valence emission is interpreted in a one-electron picture as a measure of the local {ital p}-type partial density of states. The yttrium and oxygen valence emission bands are very similar and strongly resemble published photoelectron spectra. Using local-density approximation electronic structure calculations, we show that the broadening of the Y-4{ital p} signal in yttrium oxide relative to Y metal are due to two inequivalent yttrium sites in Y{sub 2}O{sub 3}. Features present in the oxide, but not the metal spectrum, are the result of overlap (hybridization) between the Y-4{ital p} wave function and states in the oxygen 2{ital s} subband. {copyright} {ital 1996 The American Physical Society.}