The ionic conductivity and dielectric properties of Ba1−xSnxF2 solid solutions prepared by mechanochemical milling

• New Ba1−xSnxF2 compositions have been synthesized by the mechanochemical milling.
• Considerably higher ionic conductivity is obtained when increasing SnF2 content.
• The increased conductivity is due to the enhanced mobility of fluoride ions

Solid solutions of Ba1−xSnxF2 fluoride ion conductors, with x = 0.1–0.4, have been synthesized by the mechanochemical milling technique for the first time. All of the prepared materials crystallize in the cubic fluorite-type structure, which indicates that the solid solution can be synthesized in the studied composition range by the mechanochemical milling technique at ambient temperature and pressure. The ionic conduction of the investigated materials has been studied by impedance spectroscopy. The ionic conductivity increased considerably, by up to six orders of magnitude compared to pure un-milled BaF2, with increasing SnF2 content. From the analysis of the conductivity spectra of the investigated materials it is found that the concentration of mobile fluoride ions is independent of temperature with almost the same values for the investigated materials. The present results suggest that the enhanced mobility of mobile ions is the origin of the higher ionic conductivity. The dielectric properties and the associated relaxation phenomena of the current materials are also described.