The influence of barium doping on the oxygen-ion diffusion and phase transition in

the La2Mo2−yWyO9 (y = 0, 1) oxide-ion conductors was investigated via dielectric

measurements. In the Ba-doped La2Mo2O9 samples there were only two dielectric

relaxation peaks Pd1 and Pd2, which were associated with the short-range diffusion

of oxygen vacancies. But in the Ba-doped La2MoWO9 samples, three peaks were

detected, including peaks Pd1, Pd2, and Ph. The last was associated with the phase

transition process from the static disordered state to the dynamic disordered state of

oxygen ion/vacancy distribution. With the increasing amount of Ba2+ in

La2MoWO9 sample, the Ph peak shifts to higher temperature, while the height and

width of Ph peak increase. Based upon the ionic radius and substitution sites of

Ba2+ and W6+ the substitution effects on the phase transition corresponding to peak

Ph were considered.

Dielectric Relaxation Studies of Ba-Doping Effects on the Oxygen-Ion Diffusion

and Phase Transition in La2Mo2−yWyO9 Ceramics. D.Li, X.P.Wang, Z.Zhuang,

Q.F.Fang: Physica B, 2009, 404[12-13], 1757-60