Protonic conduction in SmBO₃ with high-temperature phase

In this work, we investigated electrical conduction properties of SmBO₃-based materials with the high-temperature phase, in which Sm was substituted partially by Ca or Sr. From conductivity measurements at 500-925 °C, it was found that conductivities of the substituted SmBO₃ were much higher than an unsubstituted one, and were 2.9 × 10^{- 6} - 1.8 × 10^{- 4} S · cm^{- 1} under moisturized conditions at the temperature range. H/D isotope effects on conductivity demonstrated protonic conduction in the substituted specimens. Protonic conduction at elevated temperature was also confirmed by electromotive force measurements of concentration cells using the Sr-substituted SmBO₃ as the electrolyte although there was a slight contribution of electronic conduction.