Physico-chemical studies on thermal decomposition of alkali tris(maleato)ferrates(III)

The thermal decomposition of alkali tris(maleato)ferrates(III), M-3[Fe(C2H2 C2O4)(3)] (M=Li, Na, K) has been studied isothermally and non-isothermally employing simultaneous TG-DTG-DTA, XRD, Mossbauer and IR spectroscopic tech niques. The anhydrous complexes decompose in the temperature range 215-300% C to yield Fe(II)maleate as an intermediate followed by demixing of the cat ions forming alpha -Fe2O3 and alkali metal maleate/oxalate in successive st ages. In the final stage of remixing of the cations (430-550%C) a solid sta te reaction occurs between alpha -Fe2O3 and alkali metal carbonate leading to the formation of fine particles of respective ferrites. The thermal stab ilities of the complexes have been compared with that of alkali tris(oxalat o)ferrates(III).