How is cobalt oxide (II,III) synthesized, and what process parameters affect quality?

How is cobalt oxide (II,III) synthesized, and what process parameters affect quality?
Industrial routes start from a cobalt salt, usually cobalt chloride or sulfate, then build a uniform precursor before calcination. One path reacts cobalt chloride with ammonium bicarbonate to form cobalt carbonate, which is then calcined at high temperature. A second, now dominant route adds EDTA to cobalt chloride, reacts with sodium hydroxide under air oxidation, and yields near-spherical Co3O4 directly with good sphericity and high tap density. In ammonia-complexation routes, free ammonia is held around 4-6 g/L to balance nucleation and growth; too high and particles coarsen, too low and fine agglomerates form. Calcination at 350-450 degrees Celsius with controlled ramp rates converts the precursor while tuning surface area, grain size and the Co2+/Co3+ ratio.