Formation of metal oxide powders by spray-pyrolysis technique from an ethanol solution of the metal nitrate was investigated to elucidate the effects of heating rate of atomized droplets and addition of glycerine to the solution on the particle shape of the products.
α-Fe₂O₃ particles produced were spherical under a low heating rate and were inflated as the heating rate increased. At a high heating rate the particles fractured to irregular flakes.
In the formation of MgO, ZnO, and Co₃O₄ powders, on the other hand, the particles maintained the spherical form even under the high heating rate.
Addition of glycerine to the ethanol solution made α-Fe₂O₃ particles spherical and ZnO particles porous.