Investigation of proton conduction in La1−xBa1+xGaO4−x/2 and La1−xSr2+xGaO5−x/2

In this paper we report an investigation of proton conduction in two gallate systems, La1−xBa1+xGaO4−x/2 and La1−xSr2+xGaO5−x/2, containing tetrahedral Ga. Measurements in dry atmospheres show that both systems exhibit a p-type contribution to the conductivity, while a comparison between dry and wet atmospheres shows evidence for proton conduction. The La1−xBa1+xGaO4−x/2 system shows the highest proton conductivities, with conductivities reported being significantly higher (≈ 1 × 10− 4 S cm− 1 at 500 °C for x = 0.2) than those for other structures containing tetrahedral ions, e.g. LaPO4. Replacement of La by Pr in this system leads to an increase in the electronic contribution to the conductivity.