Electrical and thermal properties of Ca5Mg4−xCox(VO4)6 (0 ≤ x ≤ 4), a promising electrode material

Abstract The garnet-type solid solution Ca5Mg4−xCox(VO4)6 (0 ≤ x ≤ 4) synthesized through a solid-state reaction between the intermediates Ca3V2O8, Mg3V2O8 and Co3V2O8 crystallizes in cubic space group Ia 3 ¯ d (Z = 8) that has been confirmed by Rietveld refinement. Thermal stability has been checked from room temperature to the melting point which is 1168 °C maximum for Ca5Mg4(VO4)6. The cobalt-doped vanadates demonstrate predominantly electronic conductivity about 10–2 S·cm−1 at 850 °C. The coefficients of thermal expansion vary from 12·10−6 K−1 to 16·10−6 K−1.