Preparation of sodium ferrite from the thermolysis of sodium tris(maleato/fumarato)ferrates(III)

Thermal decomposition of sodium tris(maIeato)ferrate(III) hexahydrate, Na-3 [Fe(C4H2O4)(3)]. 6H(2)O and sodium tris(fumarato)ferrate(III) heptahydrate, Na-3[Fe(C4H2O4)(3)]. 7H(2)O has been studied upto 973 K in static air atmo sphere employing TG, DTG, DSC, XRD, Mossbauer and infrared spectroscopic te chniques. Dehydration of the maleate complex is complete at 455 K and the a nhydrous complex immediately undergoes decomposition till alpha-Fe2O3 and s odium carbonate are formed at 618 K. In the final stage of remixing of cati ons, a solid state reaction between alpha-Fe2O3 and sodium carbonate leads to the formation of alpha-NaFeO2 at a temperature (773 K) much lower than f or ceramic method. Almost similar mode of decomposition has been observed f or the fumarate complex. A comparison of the thermal stability shows that t he fumarate precursor decomposes at a higher temperature than the maleate c omplex due to the trans geometry of the former.