Doping effects on complex perovskite Ba3Ca1.18Nb1.82O9−δ intermediate temperature proton conductor

► Single phased structure formed for Ce-doped Ba3Ca1.18Nb1.82O9−δ at 1550 °C. ► Ce doping at Nb sites in Ba3Ca1.18Nb1.82O9−δ enhanced electrical conductivity. ► Ce-doped Ba3Ca1.18Nb1.82O9−δ remained chemically very stable. ► B-site-doping in Ba3Ca1.18Nb1.82O9−δ is a direction for novel proton conductors.