Both mechanical and dielectric relaxation techniques were applied to investigate the microscopic transport mechanism of O ions and to deduce the dynamical relaxation parameters in this O-ion conductor. In mechanical relaxation measurements, a prominent relaxation peak was observed around 400K at a measurement frequency of 1Hz. This was composed of 2 sub-peaks (P1 at lower temperatures and P2 at higher temperatures). As for the dielectric experiment, only 1 relaxation peak was observed above 600K when the measurement frequency was greater than 500Hz. The activation energy and the relaxation time at infinite temperature were determined to be (0.9eV, 3 x 10–16s), (1.1eV, 2 x 10–16s) and (0.99eV, 5 x 10–14s) for the P1 peak, P2 peak and dielectric peak, respectively. These relaxation parameters were all of the same order as that for O-ion diffusion in oxide ceramics; thus suggesting a mechanism of short diffusion of O ions for the 2 types of relaxation peak. An atomistic mechanism of O ion diffusion via vacancies was suggested.

Mechanical and Dielectric Relaxation Studies on the Mechanism of Oxygen Ion Diffusion in La2Mo2O9. X.P.Wang, Q.F.Fang: Physical Review B, 2002, 65[6], 064304 (6pp)