Understanding the growth mechanism of SiO2 on the surface of FeSi clusters: an MD and DFT simulation study

Inorganic oxide insulating layers of SiO2 can improve the magnetic properties of FeSi soft magnetic material. Hence, this study explored the coating and growth mechanism of SiO2 by tetraethyl orthosilicate (TEOS) deposition through adsorption on FeSi clusters via molecular dynamics and spin-polarised density functional theory simulations. The results revealed that TEOS molecules were adsorbed on the surface of FeSi cluster mainly via the O in -O-Si (OC2H5)3 groups to Fe sites. The intermolecular interaction of TEOS contributed to the formation of multi-core Si-O structure. H+ free radicals frequently diffused and migrated on the FeSi cluster surface, promoting the growth of the crystal nucleus. Four-coordinated [SiO4]4− gradually transferred O to the FeSi cluster surface and formed [SiO3]2− and SiO2, which promoted the nucleation and growth of SiO2. The findings presented herein should effectively provide a scientific basis for policymaking in further application of SiO2 materials in the field of soft magnetic materials and those who are interested in the reaction mechanism of FeSi/SiO2 core-shell heterostructure materials.