Crystallization kinetics of colloidal model suspensions: recent achievements and new perspectives

Abstract

Colloidal model systems allow studying crystallization kinetics under fairly ideal conditions, with rather well-characterized pair interactions and minimized external influences. In complementary approaches experiment, analytic theory and simulation have been employed to study colloidal solidification in great detail. These studies were based on advanced optical methods, careful system characterization and sophisticated numerical methods. Over the last decade, both the effects of the type, strength and range of the pair-interaction between the colloidal particles and those of the colloid-specific polydispersity have been addressed in a quantitative way. Key parameters of crystallization have been derived and compared to those of metal systems. These systematic investigations significantly contributed to an enhanced understanding of the crystallization processes in general. Further, new fundamental questions have arisen and (partially) been solved over the last decade: including, for example, a two-step nucleation mechanism in homogeneous nucleation, choice of the crystallization pathway, or the subtle interplay of boundary conditions in heterogeneous nucleation. On the other hand, via the application of both gradients and external fields the competition between different nucleation and growth modes can be controlled and the resulting microstructure be influenced. The present review attempts to cover the interesting developments that have occurred since the turn of the millennium and to identify important novel trends, with particular focus on experimental aspects.

Free-energy barriers for crystal nucleation from fluid phases

“…(6)} according to the classical nucleation theory is problematic, and hence tests of the theory by experiment can hardly yield conclusive results (see e.g. [37]). In this situation, a computer simulation approach to the problem appears as the most promising choice, but it also encounters conceptual problems: many techniques for obtaining ∆F * of a nucleus require a distinction which particles are part of the crystal and which particles are part of the surrounding fluid [38,39].…”

Self-Assembly of Colloidal Molecules due to Self-Generated Flow

“…We observe a rich dynamic behavior with the formation and fusion of small clusters resembling molecules, the dynamics of which is governed by an effective conservative energy that decays as 1/r. Breaking the flow symmetry, these clusters can be made active.Colloidal particles acting as "big" artificial atoms have been instrumental in studying microscopic processes in condensed matter, from the kinetics of crystallization [1] to the vapor-liquid interface [2]. Due to their size, colloidal particles are observable directly in real space.…”

Shear moduli in bcc-fcc structure transition of colloidal crystals

“…[18][19][20] It was found that classical nucleation theory (CNT) and Wilson-Frenkel law, which is usually used in atomic and molecular systems, are also applicable in colloidal crystallization though some challenges were found under some specific conditions. 4,21 Recently, the validity of the classic Ostwald's step rule (conceived by Wilhelm Ostwald as an empirical rule) has also been verified in experia) Author to whom correspondence should be addressed. Electronic mail:…”

“…[1][2][3][4][5] Furthermore, the periodic modulation of the refractive index makes it to be an attractive material, photonic crystals, having potential applications in optical fibers, displays, and sensors. [6][7][8] For charged colloidal systems consisting of submicrometer particles and the surrounding medium, one great advantage is that the interparticle interaction potential can be tuned conveniently through particles surface charge, number density, and electrolyte concentration.…”