Solid solutions of La5–xMxMo3016.5+x/2, where M = Ce4+ and Th4+ with 0.0 ≤ x < 0.3, with a fluorite-related structure have been prepared by solid-state reaction. The unit-cell parameters decrease with increasing Ce4+ content. Ionic conductivity was investigated from 200 to 700 °C by ac complex impedance measurement. The conductivity is enhanced for Ce4+ content up to x ≤ 0.25. Conductivity due to electrons was not observed. The highest conductivity was found in La4.955Ce0.05Mo3O16.525, from σ ~ 2.6 × 10−6 (Ω cm)−1 with Ea = 66 eV at 200 °C to σ ~ 8.0 × 10−3 (Ω cm)−1 with Ea = 0.51 eV at 680 °C. Differential thermal analysis, thermogravimetry, and magnetic susceptibility measurements and X-ray absorption near-edge spectral analysis were also carried out. An interstitialcy mechanism is proposed to interpret the oxide ion conduction behavior in this type of oxygen-excess system.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Materials Chemistry