Size controlled Fe nanoparticles through polyol process and their magnetic properties

The first report on the synthesis of submicron sized pure Fe particles solely by polyol process was published by the authors a couple of years ago. Recent applications in biomedical fields demand stable and high saturation magnetization particles of sizes below 100 nm. In this paper, we report the successful synthesis of size controlled Fe nanoparticles ranging between 90 and 10 nm by polyol process using H2PtCl6 as the nucleating agent. The size of cubic Fe particles synthesized without the nucleating agent was 150 nm. The gradual decrease in size was observed with the increase in Pt ion concentration and the minimum size of 10–15 nm was achieved under a Pt ion concentration of 2 × 10−7 M. The Fe particles retained their cubic morphology for sizes above 25 nm and became spherical and agglomerated with further reduction in size. Saturation magnetizations of Fe particles were size dependent and varied between 210 and 90 Am2 kg−1. The as-prepared particles with diameters up to 60 nm were highly stable in air due to the formation of a thin passive layer of Fe-oxide shell. Consequently, this particle is considered a better candidate for biomedical application than magnetite due to higher saturation magnetization and biocompatible nature of the oxide layer formed on the surface.