IONIC-DIFFUSION IN A TERNARY SUPERIONIC CONDUCTOR - AN AB-INITIO MOLECULAR-DYNAMICS STUDY

We present Car-Parrinello molecular dynamics simulations of a novel su perionic conductor, Li2-2xMg1+xSi (x similar to 0.06), at different te mperatures. The calculations clarify the nature of the ionic conductio n and lead to the prediction of the first inorganic magnesium superion ic conductor. In fact, both lithium and magnesium are found to act as charge carriers. The diffusion is fast and can be described as vacancy migration through directed jumps. The calculated diffusion constants for lithium are consistent with recent electrochemical measurements.