The structure and conductivity of orthorhombic β-YF3-structured rare-earth fluorides and of tysonite-structured ones were investigated. The temperature dependences of the conductivity of various orthorhombic crystals were found to be close to one another. The conductivity at 500K, and the conduction activation enthalpy, ΔH, were equal to 1.1 x 10−5S/cm and 0.70eV, respectively. The conductivity of the tysonite-structured crystals was significantly higher (σ500 = 1.4 x 10−3S/cm, ΔH = 0.36eV), and could be further enhanced by doping with alkaline-earth fluorides. The highest conductivity was found for LaF3:5m/oSrF2 (σ500 = 2.4 x 10−2S/cm, ΔH = 0.35eV). The conductivity was isotropic in both types of structure.

Structural Aspects of Fast Ionic Conductivity of Rare Earth Fluorides. V.Trnovcová, L.S.Garashina, A.Škubla, P.P.Fedorov, R.Čička, E.A.Krivandina, B.P.Sobolev: Solid State Ionics, 2003, 157[1-4], 195-201