Abstract:The oxide-ion current across grain boundaries in a polycrystalline LaGaO₃ ceramic doped with 1 mol% Sr²⁺ increases non-linearly with the applied dc-bias to present a transition from ohmic to superohmic where the bias exceeds the thermal voltage, verifying that a Schottky-type potential barrier exists at the grain boundary in acceptor-doped LaGaO₃ to limit the internal current.