Electric Properties of Solid Solutions Based on Strontium Tantalate with Perovskite-Type Structure. Protonic Conductivity

Conductivity of the Sr6 - 2xTa2 + 2xO11 + 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 degrees 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 degrees C, the protonic transport becomes predominant.