LAUSR

Abstract Bismuth-based oxides (AE(TM)2Bi2O9, AE: Ca, Sr, Ba; TM: Nb, Ta), including SrTa2Bi2O9, SrNb2Bi2O9, BaNb2Bi2O9, and CaTa2Bi2O9 were synthesized via a conventional solid-state reaction, and their ionic transport properties were investigated. All the materials are verified oxide ion conductors and identified in recent reports using materials informatics. The materials exhibited good oxide ion conductivities, for example, 3.3 × 10−3 S/cm at 973 K for SrTa2Bi2O9 with transport numbers > 95 %. The materials have relatively high oxide ion conductivity without doping, which does not increase conductivity. First-principles calculations show a microscopic mechanism of oxide ion transport that is characterized by the weak bonding of oxygen with Ta or Nb.