Formation, microstructure and magnetic properties of nanocrystalline MgFe2O4

Nanocrystalline powder of MgFe2O4 was successfully synthesized by a cost effective novel combustion route. Nitrates of the constituent elements and glycine were respectively used as an oxidizer and fuel to drive the reaction. The effect of glycine to nitrate molar ratio (G N-1) on the structure and formation of MgFe2O4 was studied in view of thermodynamic considerations like adiabatic flame temperature and gas evolved during the combustion. The as prepared powder was characterized by X-Ray Diffraction (XRD), Fourier Transform Infra Red (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) for formation and microstructure analysis at various G N-1 ratios. XRD results revealed that the crystallinity of MgFe2O4 is insensitive to G N-1 variations and fuel lean combustion also lead to appropriate MgFe2O4 phase formation. Thermo Gravimetric-Differential Thermal Analysis (TG-DTA) for the precursor gel demonstrated the occurrence of rapid chemical reaction between glycine and nitrates at around 194 degrees C corresponding to ignition of precursors at this temperature. Transmission electron microscopy image for as prepared stoichiometric sample shows formation of nanoparticles of sizes from 28 nm to 50 nm. SEM images of MgFe2O4 nanoparticles at G N-1 ratio show remarkable change in microstructure regarding porosity and grain size. Room temperature magnetic measurements for stoichiometric sample show the magnetization (M-s) and remanence (M-r) of about 31.56 emu g(-1) and 9.60 emu g(-1) at +/- 10 kOe respectively. (C) 2011 Elsevier B.V. All rights reserved.