Phase field modelling of crystal growth of NaCl in two dimensions

Abstract

Modelling crystal growth is important for example in crystal engineering, materials science, and the life sciences. Molecular modelling techniques can provide fundamental insights into the atomic processes underlying crystal growth but do not always give direct information about growth rates and growth modes on spatial and temporal scales relevant in nature and for applications. The phase-field (PF) approach is a relatively simple model that can provide results on length and time scales directly comparable to experiments, but it has not extensively been employed to investigate crystallization of ionic solids, and not many quantitative results have been reported. In the present study we model the growth of cubic NaCl crystals in two dimensions. We have used small crystal seeds with an appropriate anisotropy term to investigate both the growth speed and the growth mode. Results are compared to experimental data from the literature. The PF model displays the concentration dependent transition from compact to non-compact growth of NaCl reasonably well on spatial and temporal scales that are not easily accessible with other theoretical models.