Monoclinic β-Li2TiO3: Neutron diffraction study and estimation of Li diffusion pathways

A neutron powder diffraction study on lithium titanate Li2TiO3 was performed at low temperatures. The monoclinic beta-phase has been found to be stable over the whole investigated range of temperatures (4 K-300 K). A smooth and nonlinear increase of the lattice parameters has been observed upon heating and correlated to the behavior of interatomic distances. Lithium diffusion pathways in Li2TiO3 were estimated theoretically on the basis of the obtained structural data using bond-valence modeling. Experimentally diffusion pathways were evaluated by analysis of the negative nuclear scattering densities at 1073 K, which were reconstructed using a maximum entropy method. Although the bond-valence mismatch map indicated a possible Li diffusion either in ab plane or along c direction, analysis of the experimental data revealed that Li migration is thermodynamically less feasible in latter case. (C) 2016 Elsevier Masson SAS. All rights reserved.