Optimization of magnetic properties of MnFe2O4 by modulating molarity of NaOH as precipitating agent

MnFe2O4 nanoparticles were synthesized using the co-precipitation method with a wide range of molar concentrations of sodium hydroxide 0.76 M−3.0 M. X-ray diffraction, field effect scanning electron microscopy, transmission electron microscopy, and vibrating sample magne-tometry were employed to characterise the structural, morphological, and magnetic characteristics of nanoparticles. Field effect scanning electron microscopy and transmission electron microscopy images show that the particles were spherical in shape for all the samples except for sample prepared at a molar concentration of 1.3 M. Particle shape was found to depend on the molar concentration of NaOH. The hysteresis loops of the samples possessed a very small area and low coercivity. The crystallite size (cs), saturation magnetisation, coercivity, retentivity, squareness ratio and anisotropy constant were found to be dependent on the molar concentration on NaOH. M S was noted to be at a maximum of 64.4 emu g−1 at a molar concentration of 1.3 M. The ratio t/cs (where t is the thickness of the dead layer) was calculated to account for the variation in M S. H C was found to be maximum of ∼52 Oe at molar concentrations between 1.0 M and 2.0 M. M r and M r/M S were found to be a maximum of 8.95 emu g−1 and 0.15, respectively, for the molar concentration of 2.0 M.