Structural analysis of imperfect Li2TiO3 crystals

Abstract

Li2TiO3 is a Li-rich cathode/anode material similar to Li2MnO3. These materials crystallize into monoclinic structures with ABC-stacked atomic layers, approximated by pseudo-trigonal cells. In these crystals, transition-metal layers are occupied not only by transition-metal atoms but also by Li atoms, forming ordered/disordered atomic arrangements. Faults Rietveld analysis was conducted, showing that Li2TiO3 crystalizes into a monoclinic structure with the space group C2/c, in which Li and Ti atoms are configured in an imperfectly ordered arrangement at the transition-metal layer and a large number of stacking faults are generated in the crystal. To precisely evaluate the site occupancies in such imperfect crystals, our structural analysis found that the structures should be analyzed by powder diffraction while taking stacking faults and atomic mixing into account. The atomic mixing at the transition-metal layer tends to gradually increase as the synthesis temperature is raised.