Fe–Si core/Si-shell clusters prepared by double glow discharge sources

Abstract

Using an improved plasma gas condensation cluster deposition system, Fe and Si clusters are prepared by a single glow discharge source and Fe/Si hybrid clusters by double glow discharge sources without inserting a partition plate. Transmission electron microscope observations indicate the following characteristic structures and morphologies. There are a bcc phase in Fe clusters and a diamond-like phase in Si clusters. In Fe/Si hybrid clusters, bcc Fe–Si cores are covered with crystalline and/or amorphous-like Si shells. Fe and Si cluster nuclei collide with each other at an initial stage, and Si cluster nuclei cover Fe cluster nuclei probably because the surface energy of Si is much lower than that of Fe. In a clean background condition, Fe and Si atoms mix and/or internally diffuse at the contact interface between juxtaposing Fe and Si cluster nuclei, and form bcc Fe–Si and crystalline or amorphous Si phases, whereas no intermetallic compound phase is formed due to the limited diffusion condition.