Influences of Lattice Sinks and Defect Interactions on Solutes in Compounds

A thermodynamic model for the site preference of dilute solutes in ordered compounds was developed recently. The model is extended here in two ways to help interpret experimental results from this laboratory. (1) A preference for solutes to occupy sites in 'sinks' such as grain boundaries rather than regular lattice sites is included using a simple model. A wide range of site preference behavior is found; for example, a solute may switch between substitutional and sink sites with changing composition. (2) The effect of an attractive interaction between solute and defect on the site preference is examined. Conditions are established under which a solute can be stabilized by association with a defect on a site where the solute would otherwise not be found.