Phase-field crystal modeling of heteroepitaxy and exotic modes of crystal nucleation
journal contributionposted on 03.11.2017 by Frigyes Podmaniczky, Gyula Toth, Gyorgy Tegze, Tamas Pusztai, Laszlo Granasy
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We review recent advances made in modeling heteroepitaxy, two-step nucleation, and nucleation at the growth front within the framework of a simple dynamical density functional theory, the Phase-Field Crystal (PFC) model. The crystalline substrate is rep-resented by spatially confined periodic potentials. We investigate the misfit dependence of the critical thickness in the Stranski–Krastanov growth mode in isothermal studies. Apparently, the simulation results for stress release via the misfit dislocations fit better to the People–Bean model than to the one by Matthews and Blakeslee. Next, we investigate structural aspects of two-step crystal nucleation at high undercoolings, where an amorphous precursor forms in the first stage. Finally, we present results for the formation of new grains at the solid-liquid interface at high supersaturations / supercoolings, a phenomenon termed Growth Front Nucleation (GFN). Results obtained with diffusive dynamics (applicable to colloids) and with a hydrodynamic extension of the PFC theory (HPFC, developed for simple liquids) will be compared. The HPFC simulations indicate two possible mechanisms for GFN.
This work has been supported by National Agency for Re-search, Development, and Innovation (NKFIH), Hungary un-der contract No. OTKA-K-115959, by the EU FP7 Collabora-tive Project “EXOMET” (contract no. NMP-LA-2012-280421, co-funded by ESA), and by the ESA MAP/PECS projects “MAGNEPHAS III” (ESTEC Contract No. 40000110756/11/ NL/KML) and “GRADECET” (ESTEC Contract No. 40000 110759/11/ NL/KML).
- Mathematical Sciences