Characterization of AE(TM)2Bi2O9 (AE: Ca, Sr, Ba; TM: Nb, Ta) as oxide ion conductors.

• Bismuth-based oxides, AE(TM) 2 Bi 2 O 9 , identified by materials informatics, are experimentally verified as good oxide ion conductors (e.g., 3.3 × 10−3 S/cm at 973 K for SrTa 2 Bi 2 O 9 , with transport numbers of >95 %). • First-principles calculations show a microscopic mechanism of the transport properties in terms of the weak bonding of oxygen with Ta or Nb, represented by the charge transfer between Ta/Nb and oxygen. Bismuth-based oxides (AE(TM) 2 Bi 2 O 9 , AE: Ca, Sr, Ba; TM: Nb, Ta), including SrTa 2 Bi 2 O 9 , SrNb 2 Bi 2 O 9 , BaNb 2 Bi 2 O 9 , and CaTa 2 Bi 2 O 9 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 SrTa 2 Bi 2 O 9 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. [ABSTRACT FROM AUTHOR]