Transition metal oxide perovskites by photoelectron and X-ray absorption spectroscopy

Abstract

X-ray and ultraviolet photoelectron spectroscopy as well as x-ray absorption spectroscopy have been employed to investigate transition metal oxide perovskites of the general formula ABO₃ (A = La or rare-earth ion, B=trivalent transition metal ion). Systematics in the core levels and in the valence bands in the series of LaBO₃ compounds have been discussed. Lanthanum chemical shifts in the x-ray absorption spectra in this series show interesting trends. Photoelectron spectra of the solid solutions, LaNi_1-x Co_x O₃, LaNi_1-x Fe _x O₃ and LaFe_1-x Co _x O₃ show that the rigid band model is applicable to these systems. It is shown that x-ray photoelectron spectroscopy can be employed to identify multiple oxidation states of transition metal ions in oxide perovskites.