A novel electrolyte for intermediate solid oxide fuel cells

Scheelite-type, LaxCa1−xMoO4+δ electrolyte powders, are prepared by the sol–gel process. The crystal structure of the samples is determined by employing the technique of X-ray diffraction (XRD). According to XRD analysis, the continuous series of LaxCa1−xMoO4+δ (0 ≤ x ≤ 0.3) solid solutions have the structure of tetragonal scheelite. Their lattice parameters are greater than that of the original sample, and increase with increasing values of x in the La-substituted system. Results of sinterability and electrochemical testing reveal that the performances of La-doped calcium molybdate are superior to that of pure CaMoO4. LaxCa1−xMoO4+δ ceramics demonstrate higher sinterability. The La0.2Ca0.8MoO4+δ sample that achieved 96.5% of the theoretical density was obtained after being sintered at 1250 °C for 4 h. The conductivity increases with increasing lanthanum content, and a total conductivity of 7.3 × 10−3 S cm−1 at 800 °C could be obtained in the La0.2Ca0.8MoO4+δ compound sintered at 1250 °C for 4 h.