Solubility limits in Mn–Mg ferrites system under hydrothermal conditions

Abstract

In the present investigation, we successfully synthesized a pure MnFe2O4 ferrite by the hydrothermal method. Moreover, the effect of Mg ion content on the formation of Mn1−xMgxFe2O4 particles (with x varying from 0.1 to 1.0) was also investigated using XRD, SEM, TEM and Mossbauer Spectroscopy.Phases formed in the system Mn1−xMgxFe2O4; 0.0≤x≤1.0 were investigated under hydrothermal conditions at 453K.The produced phases were characterized by X-ray diffraction, Scanning, transmission microscopy and Mossbauer spectroscopy. The information of composition, cation distribution in the spinel structure and the particle size of the products were obtained. The spinel ferrites; Mn1−xMgxFe2O4 were formed in the range 0.0≤x≤0.3. However, sample with x>0.3 showed semi-crystalline magnesium hydroxide (Mg(OH)2) and hematite (Fe2O3) beside the ferrite phase. For x=1.0, only magnesium hydroxide and hematite are formed without any ferrites.Particles of uniform size around 10–20nm were obtained in the spinel structure of Mn1−xMgxFe2O4 with x=0.0 and 0.1. The corresponding average crystallite size for each sample was 40.3nm and 39.2nm respectively. In addition, the Mossbauer spectra were analyzed into two subspectra, one for the tetrahedral A-site and the other for the octahedral B-site. The Mossbauer parameters were determined and discussed for the studied system. The cation distribution was estimated from the analysis of the Mossbauer spectra as well as the X-ray diffraction patterns. The results showed that Mg ions occupy mainly B-site while both Mn and Fe ions are distributed between A- and B-sites.