Thermal decomposition of sodium tris(maleato)ferrate(III) hexahydrate, Na3[Fe(C4H2O4)3]·6H2O and sodium tris(fumarato)ferrate(III) heptahydrate, Na3[Fe(C4H2O4)3]·7H2O has been studied upto 973 K in static air atmosphere employing TG, DTG, DSC, XRD, Mössbauer and infrared spectroscopic techniques.
Dehydration of the maleate complex is complete at 455 K and the anhydrous complex immediately undergoes decomposition till
α-Fe2O3 and sodium carbonate are formed at 618 K. In the final stage of remixing of cations, a solid state reaction between α-Fe2O3 and sodium carbonate leads to the formation of α-NaFeO2 at a temperature (773 K) much lower than for ceramic method. Almost similar mode of decomposition has been observed for the
fumarate complex. A comparison of the thermal stability shows that the fumarate precursor decomposes at a higher temperature
than the maleate complex due to the trans geometry of the former.
The thermal decomposition of alkali tris(maleato)ferrates(III), M3 [Fe(C2 H2 C2 O4 )3 ] (M =Li, Na, K) has been studied isothermally and non-isothermally employing simultaneous TG-DTG-DTA, XRD, Mssbauer and IR spectroscopic
techniques. The anhydrous complexes decompose in the temperature range 215–300C to yield Fe(II)maleate as an intermediate
followed by demixing of the cations forming α-Fe2 O3 and alkali metal maleate/oxalate in successive stages. In the final stage of remixing of the cations (430–550C) a solid
state reaction occurs between α-Fe2 O3 and alkali metal carbonate leading to the formation of fine particles of respective ferrites. The thermal stabilities of
the complexes have been compared with that of alkali tris(oxalato)ferrates(III).
Thermal analysis of zinc hexa(formato)ferrate(III) decahydrate, Zn3 [Fe(HCOO)6]2 10H2O has been investigated up to 800°C in static air atmosphere employing TG, DSC, XRD, IR, ESR and Mössbauer spectroscopic techniques.
After dehydration at 160°C, the anhydrous complex decomposes into α-Fe2 O3 and zinc carbonate in successive stages. Subsequently the cations remix to yield fine particles of zinc ferrite, ZnFe2 O4 , as a result of solid state reaction between α-Fe2 O3 and zinc carbonate at a temperature (600°C) much lower than for ceramic method.
Authors:B. Randhawa, K. Prabhjinder, and Sweety Kamaljeet
Thermal decomposition of cobalt hexa(formato)ferrate(III) decahydrate, Co3[Fe(HCOO)6]2. 10H2O, has been studied up to 973 K in static air atmosphere, employing TG, DTG, DSC, XRD, ESR, Mössbauer and infrared spectroscopic techniques. Dehydration occurs in two stages in the temperature range of 340–430 K. Immediately after the removal of the last water molecule the anhydrous complex undergoes decomposition till -Fe2O3 and cobalt carbonate are formed at 588 K. In the final stage of remixing of cations, a solid state reaction between -Fe2O3 and cobalt carbonate leads to the formation of CoFe2O4 at a temperature (953 K) much lower than for the ceramic method. A saturation magnetization value of 2310 Gauss of ferrite (CoFe2O4) shows its potential to function at high frequencies.