Electric properties of solid solutions based on strontium tantalate with perovskite-type structure. Protonic conductivity

Conductivity of the Sr_{6 − 2x} Ta_{2 + 2x} O_{11 + 3x} (0 ≤ x ≤ 0.33) solid solutions with the cryolite structure was studied in the atmosphere with a high content of water vapors under temperature and oxygen activity variation in the gas phase. Appearance of the protonic conductivity component was proved at the temperatures below 700°C. It was found that protonic conductivity increases at a decrease in parameter x in the composition series, which is due to an increase of both the concentration of protonic defects formed in the structure and of their mobility. In the case of compositions with x < 0.15 at the temperatures below 550°C, the protonic transport becomes predominant.