The nanocrystalline Co3O4 was prepared at 50 ~ 90 °C and pH = 9 ~ 11 using [Co(NH3)6]3+ and Co2 + ions. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis indicated that the product was spinel-type with the space group Fd3m. The lattice constant is 0.80777(5) nm, and the oxygen parameter p. = 0.3895(7). The shape of the crystallite is spheric and the size of that is about 4 ~ 30 nm. The effect of temperature on the microstructure of the crystallite, such as the crystallite size and the distribution, the shape and the crystallinity were investigated. The mechanism of the formation and the growth of the crystallite were also discussed.

Key words: COBALT OXIDE, NANOPHASE MATERIALS, MICRO-STRUCTURE, XRD, TEM, CRYSTAL STRUCTURE, REACTION MECHANISM