Characterization of Mixed Cobalt‐Molybdenum Oxides Prepared by Evaporative Decomposition of Solutions

The synthesis of Co‐Mo oxides by the evaporative decomposition of solutions method has been investigated. The oxides were prepared from atomized metal salt solution precursors decomposed in less than 3 s in air at 700°C. The materials obtained were primarily hollow spheres (1 to 6 μm) composed of fine (100 to 500 Å (10 to 50 nm)) crystallites. CoO, Co 2 Mo 3 O 8 , and CoMoO 4 were the major crystalline phases identified. The Co‐Mo oxides were depleted in Mo relative to the precursor solutions and could not be prepared with Co/Mo atom ratios less than unity. A schematic Co‐Mo‐O isothermal section was constructed to explain the compositions, morphologies, and phase distributions observed for materials having different Co/Mo ratios. The loss in Mo was explained by the high vapor pressure of MoO 3 .