Anisotropy and Microscopic Aspects of Ion Transport in Li2B4O7 Crystals

The features of ion transport in lithium tetraborate Li2B4O7 crystals with vacancy disorder have been studied by the molecular dynamics method. It is shown that the ion transport caused by lithium ions is anisotropic. The highest values of diffusion coefficients are observed along the c axis; they amount to DLi ~ 1 × 10–6 cm2/s at temperatures close to the melting point. It is shown that lithium ions jump over distances from 1.5 to 3.5 Å via the vacancy mechanism. The length of correlated jumps may reach 6 Å.