Superior Oxygen Ion Conductivity of Lanthanum Gallate Doped with Strontium and Magnesium

The solid solution range of the La(Sr)Ga(Mg)O3 perovskite was investigated and the oxygen ion conductivities of corresponding compositions were measured. The solubility of strontium could be extended by the addition of magnesium ions to establish a balance in the oxygen vacancies associated with A and B sites. In this way, the Sr limit in the solid solution was increased to more than 20% of the La content. Doping with either Sr or Mg enhanced oxygen ion conductivity, but whereas Sr doping yielded decreased activation energy with increasing concentration, Mg produced a higher activation energy with increased Mg content. La0.8Sr0.2Ga0.9Mg0.1O2.85 was found to have the highest conductivity apart from CeO2 ‐based electrolytes at temperatures below 700°C, while La0.8Sr0.2Ga0.85Mg0.15O2.825 has the highest conductivity except for Bi2O3 at temperatures above 700°C.