A model was proposed for ionic and superionic conduction in the α, β and γ phases of the Na3Sc2(PO4)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 Na3Sc2(PO4)3 compound, it was established that the ionic conduction in the α dielectric phase was governed by the localization and delocalization of ions in deep potential wells and that hopping between the wells was caused by the interaction of ions with phonons. The superionic conduction in the β and γ phases was 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 were responsible for the flight mechanism of conduction in the superionic phases. The contribution of each conducting channel to the total conduction was taken into account through the relaxation time of charge carriers. The estimated relaxation times were close to the values determined from the data on the conducting and dielectric characteristics of the 3 phases of the compound.

Ionic and Superionic Conduction in NASICON-Like Structures of the Na3Sc2(PO4)3 Type. A.S.Nogay, Y.Huh, K.N.Yugay: Physics of the Solid State, 2005, 47[6], 1076-82