Studies on Structural, Magnetic and Thermal Properties of xFe[sub]2TiO[sub]4-(1-x)Fe[sub]3O[sub]4 (0 less than or equal to x less than or equal to 1) Pseudo-binary System

• Published in: Journal of magnetism and magnetic materials Vol. 324; no. 7; pp. 1453 - 1462
• Main Authors: Sorescu, Monica, Xu, Tianhong, Wise, Adam, Diaz-Michelena, Marina, McHenry, Michael E
• Format: Journal Article
• Language: English
• Published: 01-04-2012
• Subjects: Cations; Charge; Ferrimagnetism; Magnetite; Mossbauer effect; Spinel; Thermal properties; Weight loss
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2011.12.012

The xFe[sub]2TiO[sub]4-(1-x)Fe[sub]3O[sub]4 pseudo-binary systems (0 less than or equal to x less than or equal to 1) of ulvospinel component were synthesized by solid-state reaction between ulvospinel Fe[sub]2TiO[sub]4 precursors and commercial Fe[sub]3O[sub]4 powders in stochiometric proportions. Crystalline structures were determined by X-ray powder diffraction (XRD) and it was found that the as-obtained titanomagnetites maintain an inverse spinel structure. The lattice parameter a of synthesized titanomagnetite increases linearly with the increase in the ulvospinel component. [super]57Fe room temperature Mossbauer spectra were employed to evaluate the magnetic properties and cation distribution. The hyperfine magnetic field is observed to decrease with increasing Fe[sub]2TiO[sub]4 component. The fraction of Fe[super]2+ in both tetrahedral and octahedral sites increases with the increase in Ti[super]4+ content, due to the substitution and reduction of Fe[super]3+ by Ti[super]4+ that maintains the charge balance in the spinel structure. For x in the range of 0 less than or equal to x less than or equal to 0.4, the solid solution is ferrimagnetic at room temperature. However, it shows weak ferrimagnetic and paramagnetic behavior for x in the range of 0.4<x less than or equal to 0.7. When x>0.70, it only shows paramagnetic behavior, with the appearance of quadrupole doublets in the Mossbauer spectra. Simultaneous differential scanning calorimetry and thermogravimetric analysis (DSC-TGA) studies showed that magnetite is not stable, and thermal decomposition of magnetite occurs with weight losses accompanying with exothermic processes under heat treatment in inert atmosphere.