Dielectric relaxation was used to study the properties of oxygen ion diffusion and

phase transition in the oxide-ion conductors (La1−xLnx)2Mo2O9 (Ln = Nd, Gd, x =

0.05-0.25). Two dielectric loss peaks were observed: peak Pd at about 600K and

peak Ph around 720K. Peak Pd was a relaxational peak and associated with the

short-range diffusion of oxygen ions, while peak Ph hardly changed its position and

dramatically decreased in height with increasing frequency, exhibiting nonrelaxational

nature. With increasing Ln3+ concentration, the heights of peak Ph and

Pd increased at first and then decreased after passing through a maximum at 15%

doping. It was suggested that peak Ph was related to the phase transition of a static

disordered state to a dynamic disordered state in oxygen ion/vacancy distribution.

It was found that the 15%Gd or 15%Nd doped La2Mo2O9 samples exhibited the highest conductivity in accordance with the highest height of peak Pd at this doping

content.

Phase Transition and Oxygen Ion Diffusion in (La1−xlnx)2Mo2O9 (Ln = Nd, Gd, x =

0.05-0.25) Using Dielectric Relaxation Method. Q.F.Fang, Z.Zhuang, X.P.Wang,

D.Li, J.X.Wang: Chinese Journal of Chemical Physics, 2008, 21[3], 270-4