Preparation of ferrites from the thermolysis of transition metal ferrioxalate precursors

The thermolysis of some transition metal ferrioxalate precursors, M-3[Fe(ox )(3)](2). xH(2)O (M = Mn, Co, Ni, Cu) has been studied in a static air atmo sphere from ambient to 600 degreesC. Various physicochemical techniques e.g . TG, DTG, DTA, XRD, IR, Mossbauer etc. have been employed to characterize the intermediates and products. After dehydration the anhydrous precursors undergo decomposition to yield an iron(II) intermediate, M[Fe-II(ox)(2)] (M = Mn, Co, Ni) in the temperature range 175-290 degreesC. A subsequent oxid ative decomposition of the iron(II) species leads to the formation of alpha -Fe2O3 and MO in successive stages. Finally a solid state reaction occurs between the oxides above 400 degreesC resulting in the formation of transit ion metal ferrites, MFe2O4. The ferrites have been obtained at much lower t emperature and in less time than in the conventional ceramic method.