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  • Author or Editor: K. Gandotra x
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Abstract  

Thermal analysis of alkaline earth metal ferrisuccinate precursors, M3[Fe(C4H4O4)3]2xH2O (M=Mg, Ca) has been studied isothermally and non-isothermally employing simultaneous TG-DTG-DSC, XRD, IR and M�ssbauer spectroscopy to characterize the intermediates/end products. After dehydration, the anhydrous complexes decompose to yield an iron(II) oxalate intermediate, Fe(II)C2O4 in the temperature range 180–250�C. Decomposition of this iron(II) species leads to the formation of α-Fe2O3 and respective alkaline earth metal oxide/carbonate in the temperature range 250–300�C. Finally, ferrites of the stoichiometry, MgFe2O4 and Ca2Fe2O5 are formed as a result of solid-state reaction between α-Fe2O3 and MO/MCO3. A special feature of the precursor method, adopted by us, is that the formation of ferrites occurs at much lower temperature than that of conventional ceramic method.

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Abstract  

Thermal decomposition of transition metal malonates, MCH2C2O4xH2O and transition metal succinates, M(CH2)2C2O4xH2O (M=Mn, Fe, Co, Ni, Cu, Zn) has been studied employing TG, DTG, DTA, XRD, SEM, IR and Mssbauer spectroscopic techniques. After dehydration, the anhydrous metal malonates and succinates decompose directly to their respective metal oxides in the temperature ranges 310–400 and 400–525C, respectively. The oxides obtained have been found to be nanosized. The thermal stability of succinates have been found to be higher than that of the respective malonates.

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Summary  

The thermal decomposition of manganese tris(malonato)ferrate(III) hexahydrate, Mn3[Fe(CH2C2O4)3]2 . 6H2O has been investigated from ambient temperature to 600 °C in static air atmosphere using various physico-chemical techniques, i.e., simultaneous TG-DTG-DSC, XRD, Mössbauer and IR spectroscopic techniques. Nano-particles of manganese ferrite, MnFe2O4, have been obtained as a result of solid-state reaction between a-Fe2O3 and MnO (intermediate species formed during thermolysis) at a temperature much lower than that for ceramic method. SEM analysis of final thermolysis product reveals the formation of monodisperse manganese ferrite nanoparticles with an average particle size of 35 nm. Magnetic studies show that these particles have a saturation magnetization of 1861G and Curie temperature of 300 °C. Lower magnitude of these parameters as compared to the bulk values is attributed to their smaller particle size.

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