“…Most of the work on BIMEVOXes has focussed on a composition in which 10% of the V is partially substituted by ions such as Cu 2+ , Ni 2+ , Zn 2+ , Co 2+ , Ti 4+ , Nb 5+ , Ta 5+ , Zr 4+ [6][7][8][9][10]. The oxide ion vacancies order in ␣ and  phases of Bi 4 V 2 O 11 at low temperatures, consequently the conductivity decreases markedly, while they become most disordered with ␥-phase which possesses excellent ionic conductivities at relatively higher temperatures.…”