High-resolution EELS investigation of the electronic structure of ilmenites

Abstract

The electronic structure of a series of compounds belonging to the ilmenite family is investigated using high resolution electron energy loss spectroscopy (EELS). The energy loss near edge structure (ELNES) of the O-K, $\mathrm{Ti}\text{\ensuremath{-}}{\mathrm{L}}_{23}$ and transition metal ${\mathrm{L}}_{23}$ edges have been recorded in $\mathrm{Mn}\mathrm{Ti}{\mathrm{O}}_{3}$, $\mathrm{Fe}\mathrm{Ti}{\mathrm{O}}_{3}$, $\mathrm{Co}\mathrm{Ti}{\mathrm{O}}_{3}$, and $\mathrm{Ni}\mathrm{Ti}{\mathrm{O}}_{3}$ with an energy resolution of $0.20--0.25\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. The formal valency and spin-state of the transition metal are determined unambiguously from the analysis of the ${\mathrm{L}}_{23}$ edges with theoretical ligand field multiplet calculations. The results confirm the evolution of the interatomic distances observed along this series. The O-K edge is analyzed by comparison to the experimental signatures observed in the structurally related ${\mathrm{Ti}}_{2}{\mathrm{O}}_{3}$ compound and using theoretical molecular orbital results.