Comprehensive survey of Nd3+ substitution In La2Mo2O9 oxide-ion conductor

Differential thermal analysis Coupled to temperature-control led diffraction have given evidence of a topological metastability phenomenon in an extended compositional range of the La2-xNdxMo2O9 solid Solution. A metastable-stable phase diagram is proposed for this series of LAMOX-type fast oxide-ion conductors. In the Nd range 0<x <= 0.35, a freezing of the oxygen/vacancy disorder of the beta-phase at ambient temperature can be achieved through a splat-quenching to water-ice mixture or/and shaping/sintering into pellet. In the intermediate 0.4 <= x <= 1.2 range, the amount of beta-metastable phase grows upon substitution for powders. The negative impact of beta-metastable to alpha phase transition on conductivity tends to disappear through the partial stabilization of the P phase by shaping/sintering. (C) 2009 Elsevier Inc. All rights reserved.