Iron Nanoparticles Embedded in Silica Glass: A Computational Study

Abstract

We performed electronic structure calculations within density functional theory including ab initio molecular dynamic simulations of isolated Fe 13 and Fe 55 clusters. We observed the energy preference of icosahedral over cuboctahedral clusters for both Fe 13 and Fe 55 . The magnetic structure is ferromagnetic for Fe 13 clusters, but anti-ferromagnetic for Fe 55 clusters. The isolated clusters exhibit a HOMO-LUMO gap. Subsequently, we modeled the embedding of Fe 13 and Fe 55 clusters in silica glass, creating several models of different size. All models show a homogeneous trend after optimization, however. For embedded clusters we observed the formation of an iron oxide interface between the cluster and the dielectric matrix. The magnetization of the embedded clusters is slightly larger than the magnetization of free clusters. The small clusters retain their electronic structure around the Fermi-level, still exhibiting a HOMO-LUMO gap, despite some major geometrical distortions of the clusters.Mater. Res. Soc. Symp. Proc. Vol. 959