Simultaneous Hetero- and Isovalent Doping as the Strategy for Improving Transport Properties of Proton Conductors Based on BaLaInO4.

This work focused on the novel electrochemical energy material with significantly improved electrical properties. The novel complex oxide Ba1.1La0.9In0.5Y0.5O3.95 with layered perovskite structure was obtained for the first time. It was proven that the simultaneous introduction of barium and yttrium ions in the structure of BaLaInO4 leads to the increase in the unit cell volume of up to 4% and water uptake by about three times. The increase in the proton conductivity values was both due to an increase in the proton concentration and their mobility. The sample Ba1.1La0.9In0.5Y0.5O3.95 was a nearly pure proton conductor below 400 °C. The co-doping strategy allowed us to increase the protonic conductivity values up to two orders of magnitude and it is the successful method for the design of novel protonic conductors based on the layered perovskites.