Application of Mössbauer spectroscopy to the thermal decomposition of strontium and barium bis(CITRATO)Ferrates(III)

Abstract

The thermal decomposition of M 3 [Fe(cit) 2 ] 2 4H 2 O (M = Sr, Ba) has been studied isothermally and non-isothermally employing simultaneous (TG-DTG-DSC), XRD, IR, SEM and Mössbauer spectroscopic techniques. The anhydrous complexes decompose at 140-220 • C to yield α-Fe 2 O 3 and MC 5 H 4 O 5 (metal acetonedicarboxylate) intermediates. The latter decomposes to respective carbonate at higher temperature. α-Fe 2 O 3 and MCO 3 undergo a solid state reaction in the temperature range 400-430 • C to yield Sr 2 Fe 2 O 5 and BaFe 2 O 4 respectively. Finally above 600 • C, a solid state reaction between these products and respective metal oxides leads to the formation of M 3 Fe 2 O 7−X showing simultaneous presence of Fe(III) and Fe(IV) species. These perovskite ferrites can exhibit electrical conductivity and dielectric properties. SEM analysis shows these ferrites to be nanosized with average particle diameter of 50-55 nm.

Thermal decomposition of barium ferrate(VI): Mechanism and formation of FeIV intermediate and nanocrystalline Fe2O3 and ferrite

“…The solid state reaction between α-Fe 2 O 3 and BaCO 3 leading to BaFe 2 O 4 was also observed in the temperature range of 540-590 • C by other researchers [41]. The TEM image shows that barium ferrite in sample BF600 formed nanoparticles with a broad particle size distribution (20-1200 nm) ( Figure 7).…”

Nanostructured Materials Preparation via Condensation Ways

“…These materials are widely used in electronics owing to their specific ferro-, piezo-and pyroelectric properties; for example, BaTiO 3 is used in the capacitor industry [411]. Perovskite type ferrites M 3 Fe 2 O 7x (M ¼ Sr, Ba) with particle size of 50-55 nm are formed upon thermal decomposition of molecular citrate precursors at lower temperature (873 K) than that used in conventional ceramic production processes [471].…”