The crystal structure and electrical conductivity of proton conducting Ba0.6Sr0.4Zr1 − yYyO3 − δ

► Ba0.6Sr0.4Zr1 − yYyO3 − δ with high sintering property showed proton conduction. ► Only one second order phase transition existed in Ba0.6Sr0.4Zr1 − yYyO3 − δ. ► Solution limit of Y in Ba0.6Sr0.4Zr1 − yYyO3 − δ was below 0.125. ► Ba0.6Sr0.4Zr1 − yYyO3 − δ showed relative high conductivity among AeZrO3 systems.