Document Type : Research Paper
School of Metallurgy & Materials Engineering, Iran University of Science and Technology (IUST), Tehran, Iran.
Magnetite (Fe3O4) nanoparticles were synthesized by coprecipitation route. Coprecipitation is a simple, reproducible and accessible technique relying on the coprecipitation of Fe2+ and Fe3+ cations by NaOH as base at low temperature (~80 °C). In this work, the role of different solvents (H2O, ethylene glycol, diethylene glycol, triethylene glycol) on phase, structure, microstructure and magnetic properties were characterized by X-ray diffractometry, electron microscopy and vibrating sample magnetometry techniques. Single phase Fe3O4 nanoparticles were crystallized in water and organic solvents. The particle size decreased from 53 to 33 nm by precipitating in the presence of organic solvents in contrast to water due to the introduction of more nucleation of particles caused by decrease in surface energy. Furthermore, the organic solvents prevent particle growth by adsorbing on the nucleus surface, leading to smaller particles. The as-coprecipitated Fe3O4 nanoparticles exhibited ferromagnetic behavior without any coercivity, confirming the superparamagnetism. The maximum saturation magnetization (Ms) of 54 emu/g was achieved for the as-coprecipitated Fe3O4 nanoparticles using ethylene glycol as solvent, possibly due to their higher crystallinity. However, the Ms decreased to 41 and 45 emu/g for precipitation in the presence of diethylene glycol and triethylene glycol, respectively, due to the more particle size reduction, leading to the spin canting on the particle surface.