Atomistic simulation techniques were used to investigate the defect properties of anatase TiO2 and LixTiO2, in the bulk and at surfaces. Interatomic potential parameters were derived that reproduce the lattice constants of anatase, and the energies of bulk defects and surface structures were calculated. Reduction of anatase involving interstitial Ti was found to be the most favorable defect reaction in the bulk, with a lower energy than either Frenkel or Schottky reactions. The binding energies of selected defect clusters were also presented: for the Ti3+-Li+ defect cluster, the binding energy was found to be approximately 0.5eV, suggesting that intercalated Li ions stabilize conduction band electrons. The Li ion migration path was found to run between octahedral sites, with an activation energy of 0.45-0.65eV for mole fractions of Li in LixTiO2 for x < or = 0.1. The calculated surface energies were used to predict the crystal morphology, which was found to be a truncated bi-pyramid in which only the (101) and (001) surfaces were expressed, in accord with the available microscopy data. Calculations of defect energies at the (101) surface suggested that single Ti3+ defects and neutral Ti3+-Li+ pairs tend to segregate to the surface.

Defect Chemistry, Surface Structures and Lithium Insertion in Anatase TiO2. Olson, C.L., Nelson, J., Islam, M.S.: Journal of Physical Chemistry, 2006, 11[20], 9995-10001