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

TL;DR

Researchers developed a new one-step method to create silica-coated iron particles with magnetic properties useful for advanced materials.

Contribution

A novel single-step aerosol process was introduced for synthesizing Fe@SiO2 core–shell particles.

Findings

Excess core particles led to FeO crystal formation due to insufficient reduction.

Fewer cores resulted in thicker SiO2 shells, hindering H2 gas penetration.

Produced particles showed soft-ferromagnetic properties with high magnetic saturation.

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.

Submicron-sized core–shell Fe@SiO2 particles were successfully synthesized using a single-step aerosol technique for the first time.

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