Study on the Ti K, L2,3, and M Edges of SrTiO3 and PbTiO3.

The multiplet theory of free ions combined with crystal field theory is used to study core electron excitation of perovskites. This combined method is helpful to further identify transition peaks and comprehend the transition mechanism. In this paper, the core electron excitation of Ti K edge, L2,3 edges, and M edge in SrTiO3 and PbTiO3 is studied, and the identification of peak and the analysis of spectral shape are emphasized. Especially at the M edge, we can identify the dipole and higher-order multiple transition peaks of Ti4+. At the L2,3 edges, the transition strength corresponding to the 2p3d configuration coupling affects the shape of the spectra. The correction of the crystal field can make the theoretical spectra more consistent with the experimental spectra. For the K edge in PbTiO3, by comparing the spectral shapes and energy of Ti2+, Ti3+, and Ti4+ with experiments, the spectrum is mainly composed of Ti3+ and Ti4+, and the proportion of Ti4+ is determined to be over 91%.