Preparation of cobalt ferrite from the thermolysis of cobalt tris(malonato)ferrate(III)trihydrate precursor

Thermal decomposition of cobalt tris(malonato)ferrate(III)trihydrate precursor, CO3[Fe(CH2C2O4)(3)]center dot 3H(2)O has been investigated from ambient temperature to 600 degrees C in static air atmosphere using various physico-chemical techniques, i.e. TG-DTG-DSC, XRD, Mossbauer and IR spectroscopic techniques. The precursor undergoes dehydration and decomposition simultaneously to yield cobalt malonate and iron(II) malonate intermediates at 205 degrees C. At higher temperature (325 degrees C) these intermediate species undergo exothermic decomposition to yield CoO and alpha-Fe2O3, respectively. Finally cobalt ferrite, CoFe2O4, has been obtained as a result of solid-solid reaction between Fe2O3 and CoO at a temperature (380 degrees C) much lower than that of ceramic method. SEM analysis of the final thermolysis product reveals the formation of monodisperse cobalt ferrite nano-particles with an average particle size of 45 nm. Magnetic studies show that these particles have a saturation magnetization of 3095 G and Curie temperature of 504 degrees C. Lower magnitude of these parameters as compared to the bulk values is attributed to the smaller particle size. (C) 2009 Elsevier Ltd and Techna Group S.r.l. All rights reserved.