Effect of Oxidation Condition on the Wet Synthesis of Spinel Ferrite Powders Below 60°C

抄録

Single phase of magnetite and nickelous ions substituted magnetite were respectively synthesized by bubbling oxygen into the ferrous and nickelous hydroxide suspension below 60°C. Single phase of magnetite was obtained at 20°C by setting the oxygen bubbling rate to 50 cm³min^-1. The single phase of nickelous ions substituted magnetite (molar ratio of Ni-to-Fe =1: 9) was obtained by oxidation of the reaction solution under oxygen flow rate = 10cm³min^-1 at 20°C. Because of the high solubility of oxygen, a low oxygen bubbling rate was necessary for the synthesis of spinel ferrite. The effect of addition of nickelous ions in the reaction solution on the formation of spinel phase was investigated. The formation of nickelous ions substituted magnetite was enhanced with a decrease in the oxygen bubbling rate. Nickelous ions inhibited the dissolution of hydroxide precipitate and forced the formation of δ-FeO(OH)-like phase.