Simulations were performed using a model that allowed charge transfer among ions. The ionic charges were dynamically calculated for each time step using an extended Lagrangian method. An additional Nosé-Hoover chain thermostat was used in order to keep the charges at low temperature, preventing thermal coupling between nuclear and charge degrees of freedom. The model yielded reasonable values for the ionic charges, in good agreement with quantum mechanical calculations for titanium and oxygen, and somewhat smaller values for the lithium ions. The simulations revealed an expected one-dimensional diffusion along channels parallel to the [001] direction. Lithium diffusion occurred via jumps between octahedral sites located along these channels. The diffusion coefficient of lithium was measured for 300 to 900K and for concentrations up to a 0.75 lithium/titanium atomic ratio. At room temperature, values of up to 1.1 x 10− 6cm2/s were recorded for low concentrations. The results showed that increasing the lithium concentration caused diffusion to slow down significantly and to exhibit an anomalous non-Arrhenius behavior.

Lithium Diffusion in Rutile Structured Titania. Gligor, F., de Leeuw, S.W.: Solid State Ionics, 2006, 177[26-32], 2741-6