Phase transition process in oxide-ion conductor β-La2Mo2−xWxO9 assessed by internal friction method

International audienceThe oxygen ion diffusion and phase transition in La2Mo2−xWxO9 x=0, 0.25, 0.75, 1.0, and 1.4 have been investigated by the internal friction method. In addition to the low-temperature relaxation peak associated with oxygen ion diffusion, an internal friction peak of phase transition type isobserved around 350 °C in all tungsten substituted La2Mo2O9 compounds. Based on the behavior of this peak and the ionic conduction properties, the mechanism of this peak is suggested to be associated with a transition from static disordered state to dynamic disordered state of oxygen iondistribution in anion sublattice that most probably results in a transition of the ionic conduction from the Arrhenius type to the Vogel-Tamman-Fulcher type