Proton conduction in LaSrScO3 single crystals

Transparent single crystals of La1−xSrxScO3 (x = 0.01, 0.03) were grown by the floating zone method. The optical and the electrical properties were studied by infrared absorption spectra and AC-impedance measurements, respectively. Our results showed that proton conduction becomes dominant in La0.97Sr0.03ScO3 single crystals below 700 °C. The electrical conductivity increases as the amount of Sr increases. At 600 °C, La0.97Sr0.03ScO3 had a proton conductivity of 4.89 × 10− 3 S/cm. This value is almost the same as that in the literature for La0.9Sr0.1ScO3 ceramic samples. It was revealed from infrared absorption spectra that several different sites are occupied by protons in this material. Furthermore, it was found that the intensity of high-frequency O–H bands can be related to the dopant-concentration dependence of the electrical conductivity.