Structure and conductivity of strontium-doped cerium orthovanadates Ce1−xSrxVO4 (0≤x≤0.175)

A-site substituted cerium orthovanadates, Ce1−xSrxVO4, were synthesised by solid-state reactions. It was found that the solid solution limit in Ce1−xSrxVO4 is at x=0.175. The crystal structure was analysed by X-ray diffraction and it exhibits a tetragonal zircon structure of space group I41/amd (1 4 1) with a=7.3670 (3) and c=6.4894 (1) Å for Ce0.825Sr0.175VO4. The UV–vis absorption spectra indicated that the compounds have band gaps at room temperature in the range 4.5–4.6 eV. Conductivity measurements were performed for the first time up to the strontium solid solution limit in air and in dry 5% H2/Ar with conductivity values at 600 °C ranging from 0.3 to 30 mS cm−1 in air to 30–45 mS cm−1 in reduced atmosphere. Sample Ce0.825Sr0.175VO4 is redox stable at a temperature below 600 °C although the conductivity is not high enough to be used as an electrode for solid oxide fuel cells.