Regensburg 2010 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 26: Poster Session

MM 26.80: Poster

Tuesday, March 23, 2010, 14:45–16:30, Poster C

Molecular dynamics simulations of ion transport at the crystal-melt interface during the crystallization of superionic calcium fluoride — •Detlef Stock and Peter Görnert — INNOVENT e.V., Prüssingstr. 27B, D-07745 Jena, Germany

The crystallization of superionic conductors such as calcium fluoride from the melt shows a peculiarity which is due to the liquid-like mobility of anions in the crystalline phase. To understand the atomistic mechanism of the growth process we peform nonequilibrium molecular dynamics (MD) simulations of isothermal crystal growth of calcium fluoride from its undercooled melt for the low index {100}, {110}, and {111} crystal-melt interfaces. The MD simulations are based on parameterized potentials describing long-range Coulomb and pairwise short range interactions. We investigate the ion transport at the interface in terms of ion mobility and average coordination number of the ions as a function of the distance to the interface. As a result we observe the freezing of the cation sublattice, whereas there is only a slight decrease of the anion mobility in the growing crystal. Finally, a comparison of the growth kinetics of superionic calcium fluoride with results for simple fcc metals will be given.