Morphological investigation on cobalt oxide powder prepared by wet chemical method

摘要

In this paper cobalt oxide has been prepared by wet chemical method using Co(NO_3)_2 sol (Co: 80 g/L) and NaHCO_3 sol (100 g/L) as starting materials. When organic reagent: ethanol, acetone, and Polyethylene glycol-400 (PEG-400) (all are 2 mL) or three sodium salts: sodium chloride, sodium sulfate and sodium acetate (all are 1 g) had been introduced into reaction as inert additives once every time, and the measurement of PH value, zeta potential and viscosity in all solutions retains on the same level of magnitude, but the SEM shows that specific shapes of cobalt oxide particle is obtained after firing of CoCO_3 at 300 ℃ for 2 h in air. The DLVO theory discloses effect of dielectric constant of organic reagent and steric hindrance effect is the main factor for big molecular PEG-400. By replacing partly Co(NO_3)_2 with C0Cl_2, the behavior of Cl_- is studied in the process of nucleus growth, the results show that Cl~ existed in the structure of nucleus with the content from 1300 to 2400 ppm, the structure, which can stand several time washing in an ultrasonic bath after reaction, but collapse as soon as it is fired at 300 ℃ for 2 h in air. It is reasonable to conclude that there may be directed anion chemical adsorption existed in cobaltous carbonate structure, which results in corresponding cobalt oxide particle morphology via anisotropic growth of nucleus.