Synthesis of nanosized ferrites from the thermolysis of strontium and barium hexa(formato)ferrates(III)

The thermal analysis of strontium and barium hexa(formato)ferrates(III), M-3[Fe(HCOO)(6)](2)(center dot)xH(2)O. has been carried out from ambient temperature to 800 degrees C. Various physico-chemical techniques, i.e., TG, DTG, DSC, XRD, IR, Mossbauer spectroscopy, etc., have been employed to characterize the intermediates/end products. After dehydration, the anhydrous complexes undergo decomposition to yield alpha-Fe2O3 and metal oxalate in the temperature range of 275-290 degrees C. A subsequent oxidative decomposition of metal oxalate leads to the formation of respective alkaline earth metal carbonate in successive stages. Finally, nanosized ferrites of Sr2Fe2O5 and BaFe2O4 stoichiometry have been obtained as a result of a solid-state reaction between alpha-Fe2O3 and a fraction Of MCO3. The temperature of ferrite formation is much lower than possible in the conventional ceramic method.