Stabilizing Fe Nanoparticles in the SmCo5 Matrix.

We report a new strategy for stabilizing Fe nanoparticles (NPs) in the preparation of SmCo5-Fe nanocomposites. We coat the presynthesized Fe NPs with SiO2 and assemble the Fe/SiO2 NPs with Sm-Co-OH to form a mixture. After reductive annealing at 850 °C in the presence of Ca, we obtain SmCo5-Fe/SiO2 composites. Following aqueous NaOH washing and compaction, we produced exchange-coupled SmCo5-Fe nanocomposites with Fe NPs controlled at 12 nm. Our work demonstrates a successful strategy of stabilizing high moment magnetic NPs in a hard magnetic matrix to produce a nanocomposite with tunable magnetic properties.