The thermal behaviour of the hydroxide mixtures used for the synthesis of MgFe₂O₄ spinel

The thermal behaviour of hydroxide mixtures, precursors to the synthesis of MgFe₂O₄ spinel powders, was investigated. The mixtures of hydroxides were prepared by coprecipitation reaction from nitrate solutions with an Mg/Fe atomic ratio of 1:2. The results were related to the thermal behaviour of separately precipitated components of the hydroxide mixtures. Samples prepared by mechanically mixing the separately precipitated hydroxides were also studied. The spinel formation temperature was identified by performing XRD analysis on powder samples heated to different temperatures. The presence of spinel from the thermal decomposition of coprecipitated mixtures was detected at a temperature as low as 380°C. The separate formation of MgO and Fe₂O₃ from the thermal decomposition of mechanical mixtures was observed; nevertheless the formation of MgFe₂O₄ through a solid state reaction between the oxides was noted at a temperature as low as 500°C.