https://doi.org/10.1140/epjst/e2014-02101-7
Regular Article
Heterogeneous crystallization of hard and soft spheres near flat and curved walls
1 Condensed Matter Physics Laboratory, Heinrich Heine University, 40225 Düsseldorf, Germany
2 Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
3 Institute for Theoretical Physics II: Soft Matter, Heinrich Heine University, 40225 Düsseldorf, Germany
4 Joint Institute for High Temperatures, Russian Academy of Sciences (IVTAN), Moscow 125412, Russia
5 School of Physics & Astronomy, The University of Edinburgh, Edinburgh EH9 3JZ, UK
a e-mail: Stefan.Egelhaaf@uni-duesseldorf.de
Received: 13 December 2013
Revised: 10 January 2014
Published online: 28 February 2014
Crystallization represents a long-standing problem in statistical physics and is of great relevance for many practical and industrial applications. It often occurs in the presence of container walls or impurities, which are usually unavoidable or might even be desirable to facilitate crystallization by exploiting heterogeneous nucleation. Heterogeneous nucleation relies on a seed. Here we discuss the role of the seed and concentrate on a very generic situation, namely crystallization of hard and soft colloidal spheres in the presence of flat or curved hard walls. Curvature serves as a simple means to introduce a tunable mismatch between the seed-induced crystal lattice and the thermodynamically-favoured lattice. The mismatch induces distortions and elastic stress, which accumulate while the crystallite grows. This has an important consequence: once the crystallite reaches a critical size, it detaches from the seed allowing it to relax. The relaxed crystal continues to grow in the bulk, but crystallization ceases before reaching the seed, which now represents an impurity. Therefore, while seeds favour nucleation, any mismatch, like the seed curvature or an incommensurate structure, induces unfavourable distortions and can lead to the detachment of the crystallite. An additional mechanism to relax distortions is available to soft spheres, which can exploit their interaction potential and possibly deform. The different multi-step processes have been investigated by confocal microscopy, which provides particle-level information, and compared to computer simulations and theoretical results.
© EDP Sciences, Springer-Verlag, 2014
