Exploration of Properties from Both the Bulk and Surface of Iron Silicides: A Unified Theoretical Study

The properties from both bulk phases (magnetism and thermal stability) and surface (composition, orientation, and stability) of iron silicide model compounds were evaluated by a theoretical study in combination of density functional theory, ab initio atomistic thermodynamics and Wulff construction. Magnetism, one of the properties originated from bulk phases, has been chosen as an example to demonstrate how to correlate it with local chemical environment to provide in-depth understanding. We found that increasing number of coordinative Si atoms adjacent to Fe center would cause a decrease in magnetic moment. To reveal surface structural features relevant to surface properties of iron silicides, we evaluated influence of Si chemical potential (μSi) on surface thermal stability along a range of temperature (T) and partial pressure of SiH4 (PSiH4). It turns out that the thermal stability of the Si-rich surfaces has been improved as increasing μSi under high T and PSiH4. We then acquired surface free energy o...