Optimum Saturation Magnetization of Superparamagnetic Iron Oxide Nanoparticles for Versatile Applications

Abstract

Due to their unique properties, magnetic nanoparticles are interesting for the fundamental study of materials science and their applications. Specifically, iron oxide nanoparticles have a wide range of applications, for example in electronic, environmental, and medical areas. In many applications, iron oxide nanoparticles with superparamagnetic behavior and high saturation magnetization are preferred since optimum magnetic properties provide better magnetic control over the nanoparticles. In the study, superparamagnetic iron oxide nanoparticles were synthesized by co-precipitation under an inert atmosphere, and the impact of most effective parameters (reaction temperature and alkali concentration) on their structural and magnetic properties was investigated. The reaction temperature was changed from 30 to 90^◦C, and then the alkali concentration was changed at a fixed reaction temperature. It was found that the saturation magnetization of the superparamagnetic iron oxide nanoparticles increased with the increase in reaction temperature, and the maximum saturation magnetization obtained was 67.9 emu/g with zero coercivity at 75^◦C. It was also observed that the particle size increased as the reaction time increased. The saturation magnetization of the super-paramagnetic iron oxide nanoparticles synthesized using different alkali concentrations changed between 64.6 and 67.9 emu/g, and the particle size slightly decreased as the concentration decreased. The highest saturation magnetization (67.9 emu/g) with good crystallinity and relatively narrow size distribution was obtained at 75^◦C and using the highest alkali concentration. The synthesized superparamagnetic iron oxide nanoparticles may be used in a variety of potential applications, such as the removal of pollutants from water, magnetic separation, magnetic resonance imaging, etc.