Abstract: A novel method, involving high temperature gas-solid hydrolysis, was proposed for the preparation of micro-Co₃O₄ powder. The effects of reaction temperature, crystal water content of CoCl₂, the addition of inert dispersate on the product were investigated. The composition,morphology, and particle size of the prepared particle are characterized by X-ray diffraction(XRD), Scanning electronmicroscope(SEM) and Laser particle size analysis. The results indicate that the obtained powder with octahedral crystal structure are surrounded by {111} crystal surfaces. And the size ranges from submicron to micron, the particle size increases with the temperature elevating, the size distribution becomes narrow when CoCl₂·2H₂O is employed as precursor. The addition of inert dispersate is beneficial to the monodispersity of the obtained powder. The reasons for the formation of octahedral crystal morphology and the influencing factors of the particle size and morphology are also discussed.

Key words: tricobalt tetraoxide, gas-solid hydrolysis, cobalt chloride, morphology and size