SUPERIONICITY AS A LOCAL FLUCTUATION OF THE CHEMICAL-BOND

A microscopic model is proposed for the fast ion transport in solids. It is suggested that the change of bonding which occurs locally and fluctuates in time is the key mechanism responsible for the superionicity. The change of bonding is considered to be driven by the lattice vibration. In order to corroborate the idea, the bonding nature of binary compounds have been studied by using a pseudopotential theory. It is concluded that the real space pseudopotential which reflects the valence electron distribution, provides useful information to understand the link between the ion transport and the electronic structure of the materials.