Impact of atomic thermal motion on the Ti <i>L</i> 2,3-edge fine structure

This review examines the effects of thermal vibrations on core-level excitation spectra, with a particular emphasis on the Ti L 2,3-edge spectra of cubic perovskite-type titanium oxides (SrTiO3 and PbTiO3). Based on combining scanning transmission electron microscopy energy-loss near-edge structure analyses with cluster-type crystal-field multiplet calculations, the influence of atomic thermal vibrations on the fine structure of the Ti L 2,3-edge is investigated, and it is demonstrated that the thermal vibration of oxygen atoms in cubic SrTiO3 can be estimated from the spectrum by fitting experimental and theoretical results. The same approach was extended to cubic PbTiO3 such that isotropic thermal vibrations were identified that relate to the difference in the transition to a low-temperature tetragonal phase. Although the present technique does not directly resolve phonon modes, it treats thermal factors as adjustable parameters, enabling the identification of subtle vibrational features even in materials already widely studied. Further investigation of the relationship between thermal vibrations and the fine structure of core-loss spectra could assist in elucidating certain material properties. This review explores the effects of thermal vibrations on Ti L 2,3-edge spectra of cubic perovskite oxides (SrTiO3, PbTiO3). Combining STEM-ELNES with crystal-field multiplet calculations, it shows that oxygen thermal vibrations can be estimated from spectral fitting, revealing subtle vibrational features and their relation to phase transitions.