Ionic mobility, ionic transport, and charge transfer mechanism in solid solutions (1 − x)PbF2-xMF n by the NMR and impedance spectroscopy data

Abstract

The internal mobility and ionic conduction of solid solutions in systems PbF2-MF2 and PbF2-MF3 are studied by the NMR (19F, 27Al, 207Pb) and impedance spectroscopy methods. Factors that define the form of ionic movements and their energy characteristics in the temperature region 150 to 550 K are considered and analyzed. Temperature shifts of the frequency range that defines the ionic conduction of solid solutions are discovered on the basis of impedance spectroscopy data and explained. It is established that the high ionic conductance in lead difluoride doped with fluorides of metals of Groups II and III is caused by the diffusion of fluoride ions. The large values of specific conductance (10−4 to 10−3 S cm−1) at a relatively low activation energy (less than 0.6 eV) allow one to consider the solid solutions studied in the role of a basis for the obtaining of new fluoride materials with high ionic conductance.