Механизм электропереноса в суперионном проводнике Sr-=SUB=-0.7-=/SUB=-La-=SUB=-0.15-=/SUB=-Lu-=SUB=-0.15-=/SUB=-F-=SUB=-2.3-=/SUB=- со структурой флюорита

Abstract

The ionic conductivity of the superionic conductor Sr0.7La0.15Lu0.15F2.3 with the fluorite-type structure (type CaF2, sp. gr. Fm-3m) had measured by the impedance spectroscopy in the temperature range 385–794 K. Bulk crystals of a three-component solid solution (lattice parameter a = 5.7726(1) A) had obtained from the melt by the directed crystallization technique. Temperature dependence ionic conductivity σdc(T) satisfies the Arrhenius–Frenkel equation with the activation enthalpy of the electrical conductivity Hσ = 0.706 ± 0.05 eV. The value of σdc is 1.5 10–5 S/cm at 500 K. Based on the analysis of electrophysical and structural studies of fluorite-type solid solutions in SrF2–LaF3 and SrF2–LuF3 systems, the microscopic model of ion transport in the Sr0.7La0.15Lu0.15F2.3 crystal was proposed. The concentration and mobility of charge carriers were calculated: nmob = 7.8 × 1020 cm–3 and μmob = 1.2 × 10–7 cm2/Vs at 500K.