Pohorenko Y. Electrical conductivity of complex fluorides of lead, tin and rare earth elements

It has been found the fluorine anions in the synthesized fluoride-conducting phases occupy three structurally non-equivalent positions. The conductivity of the synthesized compounds is determined by interstitial fluorine anions, whose concentration depends of the composition and structure of the synthesized compounds and increases with temperature. It has been found at temperature below 350 K the conductivity of solid solutions is practically independent of REE fluoride concentration, and at temperatures above the faradaic phase transition, it increases with REE trifluoride content. In this case, the activation energy of ionic conduction decreases, which speaks for charge transfer by interstitial fluorine anions. It has been found that the transport numbers of fluorine anions are close to the theoretical ones and are practically independent of the concentration of substituents. The electronic conductivity of the synthesized compounds is by several orders of magnitude lower than the ionic one.