Nanostructuring silica-iron core–shell particles in a one-step aerosol process

Abstract

Silica-coated iron (Fe@SiO₂) particles have attracted considerable interest as a potential powder core material due to their distinctive advantages, including higher magnetic saturation and enhanced electrical resistance. In this study, the submicron-sized core–shell Fe@SiO₂ particles were successfully synthesized in a single step via an aerosol process using a spray pyrolysis method assisted by a swirler connector for the first time. Changing the reducing agent concentration (supplied H₂) and tuning the number of core (Fe) particles were investigated to achieve the desired Fe@SiO₂ particles. The results indicated that an excessive number of cores led to the appearance of FeO crystals due to insufficient reduction. Conversely, an insufficient number of cores resulted in a thicker SiO₂ shell, which hindered the penetration of the supplied H₂ gas. Furthermore, the produced Fe@SiO₂ particles exhibited soft-ferromagnetic characteristics with an excellent magnetic saturation value of 2.04 T, which is close to the standard theoretical value of 2.15 T. This work contributes new insights into the production of core–shell Fe@SiO₂ particles, expanding their applicability to advanced soft-magnetic materials.