Trivalent cation substitution of pulverulent cobalt—iron molybdates Co1 − xFexMoO4

Abstract Different mixed cobalt—iron molybdates Co1 − xFexMoO4 (0 ≤ x ≤ 1) have been prepared by means of a ceramic process. The oxidation of pulverulent samples leads to ferric molybdate Fe2(MoO4)3, spinelle Co3O4 and cobalt molybdate CoMoO4. After a strong grinding which reduces the grain size (about 0.1 μm) and induces crystallographic defects in the grains, the cobalt—iron molybdates can be partially oxidized into cation-deficient phases. This oxidation corresponds to an isostructural substitution of part of the Fe2+ and Co2+ ions by Fe3+ and Co3+ ions and the creation of cation vacancies. The concomitant presence of trivalent cations and associated cation vacancies in the lattice stabi…