A comparative analysis of the electrophysical (ionic conductivity, enthalpy of ion transport activation) and crystal chemical (lattice parameters, ionic radii, cation polarizability) characteristics of scandium-containing solid electrolytes MScF (M = Ca, Sr, Ba, Pb) has been conducted. The MScF solid solutions with the fluorite-type structure (space group) were grown from the melt using vertical directional (single crystals, M = Ca, Sr, Pb) and spontaneous (polycrystalline alloys, M = Ba) crystallization methods. The fluoride-ion conductivity of solid solutions based on the BaF and β-PbF fluorite-type matrices is 5–6 orders of magnitude higher, while the enthalpy of ion transport activation is 2–4 times lower, compared to the corresponding characteristics of solid solutions based on CaF and SrF. The high conductivity of the MScF (M = Ba, Pb) solid electrolytes is attributed to the large ionic radii of the Ba and Pb cations (size factor) and the high polarizability of the Pb cations (polarization factor). The influence of these factors leads to an increase in free space and a reduction of potential barriers for the migration of mobile fluoride ions.
Н.И. Сорокин (Wed,) studied this question.