Effect of Reaction Temperature on Particle Size of Iron Oxide Nanoparticles via Heating of Platelet ${\alpha }$ -FeOOH in Tetraethylene Glycol

We investigated the effect of reaction temperature on particle size of spinel-structured ferromagnetic iron oxide particles obtained by heating the platelet α-FeOOH particles in tetraethylene glycol (TEG). This method is advantageous as it enables the omission of outer SiO₂ shell layer and makes the surface modification easier. Oxide samples were reduced from α-FeOOH particles using TEG. The Fe₃O₄ particles were obtained through the formation of α-Fe₂O₃. The particles with single-phase Fe₃O₄ were obtained by heating above the temperature of 290 °C and confirmed by X-ray diffraction and Mössbauer spectroscopy. Among these single-phase Fe₃O₄ particles, a large proportion of relatively small-sized particles was obtained by increasing the reaction temperature to 310 °C. Fe₃O₄ particles sized 30-80 nm were finally obtained after heating at 310 °C for 60 min with the saturation magnetization of 83 Am²/kg and a coercive force of 13 kA/m.