Reducibility of fast oxide-ion conductors La2−xRxMo2−yWyO9 (R = Nd, Gd)

Abstract

The substitutional range and cell parameter evolution of fast oxide-ion conductors La_2−xR_xMo_2−yW_yO₉ (R = Nd, Gd) are investigated. In the whole series, the cubic β-La₂Mo₂O₉ structural type is stabilized at room temperature. The effects on reducibility of both single and double substitutions are presented. Lanthanum substitution by rare earth appeared to be responsible for an increase in the reducibility and a strong but reversible amorphization under dilute hydrogen. On the contrary, the favourable role of tungsten on the compound stability under reducing conditions is evidenced: it depletes oxygen loss while making the La₂Mo₂O₉ structural type less affected by it.