IONIC TRANSPORT MECHANISMS IN OXIDE-BASED GLASSES IN THE SUPERCOOLED AND GLASSY STATES

A model for ionic transport in glasses is proposed assuming that, like for ionic crystals, the displacement of cations would result from the migration of interstitial pairs. The formation of these pairs is supp osed to be an activated function of the temperature and their migratio n to be dominated by an activated jump mechanism at low temperature an d by a free volume co-operative mechanism above the vitreous temperatu re. Using numerical fits for conductivity data in the whole temperatur e range, that change of mechanism enables the determination of the def ect formation enthalpy and its migration enthalpy in the low temperatu re domain.