Synthesis of monodisperse Fe@SiO ₂ core‐shell nanocapsules and investigation of their magnetic behaviour

Abstract

The monodisperse Fe@SiO 2 core-shell nanocapsules were synthesised via hydrothermal reaction followed with heat treatment. Nanostructures were characterised by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The magnetic properties of Fe@SiO 2 nanocapsules were evaluated with magnetic property measurement system. The results show that Fe@SiO 2 core-shell nanocapsules are highly monodispersed. The silica thickness of Fe@SiO 2 nanocapsules increased from 10-20 to 25-35 nm with increasing tetraethyl orthosilicate (TEOS) amount. In the Fe@SiO 2 nanocapsules prepared with 900 μl TEOS, as the reaction temperature increases, the mean particle size of Fe@SiO 2 nanocapsules increases from 328 to 546 nm. It is remarkable that the saturation magnetisation of Fe@SiO 2 nanocapsules decreases with increasing silica thickness. However, the coercivity of nanocapsules has less influence with the variation of silica thickness and particles' length.

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

“…To address these issues, silica-coated iron (Fe@SiO 2 ) particles with core-shell structures have been recognized as promising candidates. [8][9][10][11] Fe@SiO 2 particles play a key role in minimizing eddy current losses by isolating the conductive Fe core from the surrounding environment, thereby enhancing the resistance of the core material to oxidation. 12 The insulating properties of the SiO 2 shell prevent the ow of eddy currents inside the core, enhancing the efficiency of devices based on these particles and reducing power dissipation.…”

“…In a multiple-step process, the Fe@SiO 2 particles with different morphology are synthesized through two or more processes involving Fe particle formation followed by the deposition of SiO 2 onto the Fe core. 11,12,[21][22][23][24] The detailed recent report of these processes is shown in Table S1, ESI. † These processes were performed by combining gas, solid, and liquid phase methods in a relatively long time.…”

Controllable microemulsion method for the synthesis of Mg(OH) 2 /PS core–shell structures

“…Coating polymer on the magnesium hydroxide surface to form a stable core-shell structure is an effective way to achieve modification purpose. At present, there are many reports on inorganic-inorganic core-shell materials, such as the synthesis of Pt-SiO 2 , Fe 2 O 3 @TiO 2 , CdS/TiO 2 , Fe@SiO 2 [18][19][20][21], and microemulsion method plays a certain role in the construction of the core-shell material [18]. As to inorganic-polymer composite, Jassim prepared ZnO/polystyrene nanocomposite films via sol-gel process [22], Jang synthesized CdS/PMMA core/shell nanoparticles using dispersion-mediated interfacial polymerization [23], and Guo constructed MnO 2 @PPy nanorods via an in situ self-polymerization process [24].…”