Abstract
A model is proposed for ionic and superionic conduction in the α, β, and γ phases of the Na 3 Sc 2 (PO 4 ) 3 compound. This model accounts not only for the conducting properties of the aforementioned phases but also for their structural and kinetic parameters. Within the kinetic approach to the description of the electrical conduction in the Na 3 Sc 2 (PO 4 ) 3 compound, it is established that the ionic conduction in the α dielectric phase is governed by the localization and delocalization of ions in deep potential wells and that hoppings between the wells are caused by the interaction of ions with phonons. The superionic conduction in the β and γ phases is associated both with the increase in the contribution of the ion delocalization in potential wells due to a decrease in their depth and with the decrease in the contribution of the ion localization. These contributions are responsible for the flight mechanism of conduction in the superionic phases. The contribution of each conducting channel to the total conduction is taken into account through the relaxation time of charge carriers. The estimated relaxation times are close to the values determined from the data on the conducting and dielectric characteristics of the α, β, and γ phases of the Na 3 Sc 2 (PO 4 ) 3 compound.