Synthesis and Characterization of Iron/Iron Oxide Core/Shell Nanocubes

Abstract

Abstract A simple method for the preparation of iron/iron oxide nanoparticles with core/shell cubic morphology is presented. The synthesis of the nanocubes was carried out through decomposition of a preformed iron oleate complex at high temperature. Although this procedure has been shown previously to produce monodisperse magnetite spheres, [1] the use of squalene as a solvent and the presence of sodium oleate was found to induce cube formation. A detailed high‐resolution transmission electron microscopy (HRTEM) analysis of the nanocubes was performed for structural characterization. The core/shell structure, an iron core surrounded by magnetite (Fe 3 O 4 ) shell, was confirmed by fast Fourier transform (FFT) filtering analysis. The results obtained by HRTEM analysis are in agreement with X‐ray Photoelectron Spectroscopy (XPS) and magnetic analysis. The Fe nanocubes are superparamagnetic at room temperature with a saturation magnetization M S = 101 A m 2 kg –1 and magnetic anisotropy density K eff = 1.6 × 10 5 J m –3 at low temperatures.