MOSSBAUER STUDIES ON THERMAL-DECOMPOSITION OF SOME ALKALI TRIS(MALONATO)FERRATE(III) TETRAHYDRATES

Thermal decomposition of some alkali tris(malonato)ferrate(III) tetrah ydrates, i.e. M-3[Fe(CH2C2O4)(3)]. 4H(2)O (M = Na, K) has been studied in the temperature range of 433-973 K in static air atmosphere using Mossbauer, IR and TG-DTG-DTA techniques. Mossbauer spectra are reporte d at different stages to study the mechanism of decomposition. The anh ydrous complex decomposed into alpha-Fe2O3 of varying particle sizes a nd alkali metal malonate/carstage of remixing of cations, a solid stat e reaction between alpha-Fe2O3 and alkali metal carbonate/oxide gives fine particles of the respective ferrites at temperatures lower than f or oxalate precursor or even for ceramic method. Thermal stability obe ys the order: sodium > potassium > lithium tris(malonato) ferrate (III ).