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 fl uctuates in time is the key mechanism responsible for the superionicit y. The change of bonding is considered to be driven by the lattice vib ration. 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 valen ce electron distribution, provides useful information to understand th e link between the ion transport and the electronic structure of the m aterials.