Effect of composition on structural and magnetic properties of nanocrystalline Ni0.8-xZn0.2MgxFe2O4 ferrite

Nanocrystalline magnetic particles of Ni0.8-xZn0.2MgxFe2O4 ferrites with x lying between 0.0 and 0.8 were synthesized using metal nitrates and freshly extracted egg-white. The synthesized powders were characterized using X-ray diffraction (XRD). Fourier transform infrared (FT-IR) and transmission electron microscopy (TEM). With increasing magnesium concentration, the lattice constant increases while X-ray density decreases. The average crystallite size determined from XRD data using Scherrer formula lie in the range of 35-59 nm. TEM image shows spherically agglomerated particles with average crystallite size agreed well with that obtained from XRD. Magnetic properties measured at room temperature by vibrating sample magnetometer (VSM) reveal a decrease in saturation magnetization up to Mg content of 0.6. In agreement with FT-IR results, the unexpected increase in the magnetization at Mg content of 0.8 can be attributed to the tendency of Mg2+ ions to occupy the tetrahedral site. The decrease in the value of coercivity with increasing magnesium content can be explained based on the magneto-crystalline anisotropy. (C) 2010 Elsevier Ltd. All rights reserved.