Bain paths and strained tetragonal states in metals
Tid: Ti 2017-03-28 kl 13.30
Plats: Sal Kuben, Brinellvägen 23, KTH
Föreläsare: Stephan Schönecker
Paths of tetragonal structures connecting tetragonal phases, including those with body-centered cubic and face-centered cubic symmetry, are called Bain paths. Two physically realizable paths are the epitaxial Bain path (EBP) and the uniaxial Bain path (UBP). The former is produced by isotropic biaxial stress in the (001) plane of tetragonal states, whereas the latter is due to applied stress along the  axis. Although corresponding to different physical situations, both realizations pass through the same possible sequence of minima and saddle points of energy. In my docentpresentation, I will give an introduction to the EBP and UBP and show how both permit identification of stable and possibly metastable tetragonal phases using the example of the transition metals family. I will give examples of how both paths of deformed lattices have been employed in density functional modeling and prediction of new ferromagnetic elements, isostructural instabilities in epitaxial films, and the strength and ductility of pristine crystals.