The influence of K doping on O-ion diffusion and the ionic conduction in the La2Mo2O9 oxide-ion conductors was systematically investigated via the dielectric and mechanical relaxation techniques and the dc conductivity measurements. Two relaxation peaks were observed in the K-doped samples. It was found that the partial substitution of K+ ions at La3+ sites increased the activation energy of O ion diffusion, which could be understood because K+ ions have a larger ionic radius in the crystal lattice and a greater chemical affinity with O ions in comparison with La3+ ions. Based on the results of conductivity measurements, it could be concluded that K doping could effectively suppress the phase transition and the highest conductivity at lower temperatures was obtained in the 2.5%K-doped La2Mo2O9 samples.

Influence of Potassium Doping on the Oxygen-Ion Diffusion and Ionic Conduction in the La2Mo2O9 Oxide-Ion Conductors. X.P.Wang, Z.J.Cheng, Q.F.Fang: Solid State Ionics, 2005, 176[7-8], 761-5