Synthesis of Cobalt Spinel: Effect of Mechanical Activation and Magnesium/Zinc Ion Doping

Resumo

Thermal analysis was used to study the behavior of different cobalt oxides (CoO, Co₂O₃, and Co₃O₄) upon heating. At 200 – 850°C Co₂O₃ gradually transforms into Co₃O₄, which at about 920°C transforms into CoO. The effect of mechanical working in planetary and ball-ring mills on the yield of the spinel CoAl₂O₄ and its crystallite sizes at different temperatures was analyzed. The effect of the dopants MgO and ZnO on the pigment particle sizes and color was evaluated. Using several ceramic bodies, the synthesized compounds were tested as pigments introduced into engobe, glaze, and under- and overglaze paint.