Calcium ferrite formation from the thermolysis of calcium tris (maleato) ferrate(III)

摘要

For preparing calcium ferrite, calcium tris (maleato) ferrate(III) precursor was prepared by mixing aqueous solutions of iron(III) maleate, calcium maleate and maleic acid. Various physico-chemical techniques i.e. TG, DTG, DTA, Mossbauer, XRD, IR etc have been used to study the decomposition behaviour from ambient to 900 deg C and ferrite formation. Three consecutive decomposition steps leading to the formation of #alpha#-Fe_2O_3 and calcium carbonate have been observed at various stages of thermolysis. In the final stage the ferrite, Ca_2Fe_2O_5, is obtained as a result of solid state reaction between #alpha#-Fe_2O_3 and calcium carbonate at 788 deg C, a temperature much lower than for ceramic method. The results have been compared with those of the oxalate precursor.