Dielectric relaxation studies of Bi-doping effects on the oxygen-ion diffusion in La_2-xBi_xMo₂O₉ oxide-ion conductors

Two dielectric relaxation peaks associated with oxygen-ion diffusion in the oxide-ion conductors La_2-xBi_xMo₂O₉ (x=0.05, 0.1, and 0.15) have been studied. It is found that the activation energies of the two peaks increase with increasing Bi-doping concentration, which results from the blocking effects of the lone-pair electrons of Bi³⁺ ions. From the different effects of Bi doping on the two peaks, the diffusion paths of oxygen ions corresponding to each peak are confirmed. Significantly, it is revealed that Bi doping could enhance the ionic conductivity of La₂Mo₂O₉ at lower temperatures. © 2002 American Institute of Physics.