The Preparation,Characterization And Growing Mechanism Research Of The Cobalt Oxide Nanopowder Through Solid-state Reactions

The precursor of C0304 nanopowder is synthesized through solid state reaction between the starting material CoSO4 2H2O and H2C2O4 2H2O at ambient temperature. The effect of the Processing technology on the morphology, particle size, yield and decomposition process is discussed. The effect of the Processing technology on the morphology of the CoC2O4 was studied, and the pressure is the necessary condition for the needle p-CoC2O4, and the mol ratio of the starting material and the annealing temperature also have effect on the morphology of the CoC2O4. When the precursor is prepared with a pressure of 20MPa and the mol ratio of CoSO4 7H2O and H2C2O4-2H2O 1.2: 1 at 5, the needle p-CoC2O4 with desirable morphology is obtained through annealing the precursor at 200-230.The activate energy of growing is 16KJ/mol obtained through analysis the relationship of the annealing temperature and the particle size. When the annealing temperature increases from 250 ℃ to 650 ℃ the average particle size increases from 17nm to 42nm. The research shows that as the annealing time goes on, the C0304 nanopowder grows up through the following steps: nucleus formation; h harmonious growth; unconventional growth and homogenization. The relationship of the growth of the C03O4 nanopowder and the annealing time at 500 and 650 was studied. The process of growth can be divided into the fast growth process and the slow growth process, and both of them accord with the G-M model. The kinetics equation is:At 650 the v equals 3.47 and 2.1 at the fast andslow growth process; At 500 the v equals 3.3 and 2.4 at the fast and slow growth process. So at the fast growth process the surface diffusion is the major mechanism of the growth, and at the slow growth process the body diffusion is the major mechanismof the growth.The misconstruction of the C0304 nanopowder was researched. The lattice exhibits lattice expansion as the particle size decreases. The reason of this phenomenon is discussed. The FTIR of the C03O4 nanopowder exhibits red shift and wider, the reason is also discussed from the bond length and the hydrogenous bond.