Confined binary two-dimensional colloidal crystals: Monte Carlo simulation of crack formation

Abstract

Binary mixtures (A, B) of colloidal particles of different sizes in two dimensions may form crystals with square lattice structure (the A-particles occupying the white sites and the B-particles the black sites of a checkerboard). Confining such a system by two parallel 'walls' a distance D apart, long-range order in the direction parallel to the walls is stabilized by 'corrugated walls' that are commensurate with the lattice structure but destabilized by structureless 'hard walls', even if there is no misfit between the strip width D and the crystal lattice spacing. The crossover to quasi-one-dimensional behavior is studied by Monte Carlo simulations, analyzing Lindemann parameters and displacement correlation functions. When D is reduced and thus a misfit created, the stress in the crystal increases up to a critical value, at which the stress jumps to much smaller values due to the formation of an (almost periodic) crack pattern. These cracks typically have a width of several particle diameters, and are mostly disordered, although sometimes small domains with hexagonal order can be identified. At very large misfits, glass-like structures appear. We discuss various methods to characterize order and disorder in such systems.

Facile fabrication of centimeter-scale stripes with inverse-opal photonic crystals structure and analysis of formation mechanism

“…Brittle fractures occur to quickly release the stress, forming numerous cracks. The accumulated inner stress is released intermittently, not regularly, in agreement with the theoretical simulations presented by Stefan Medina et al [37][38][39] Inner stress also accumulates along the thickness of the stripe, inducing stripe peeling from the substrate surface. According to the analysis shown in Fig.…”

Langevin dynamics simulations of a two-dimensional colloidal crystal under confinement and shear

“…A further motivation to use this model potential is that it is essentially the same potential used in the studies of confinement effects on colloidal crystals without shear [23][24][25][26][27][28] and of two-dimensional melting [42]. This potential is defined as [39,40]:…”

“…Additional studies have investigated the melting [29], the deformation [30], the correlation between channel geometry and pattern formation [31,32] and frustration [33] of such two-dimensional systems of purely repulsive particles under confinement. Others have considered binary mixtures which crystallize into a square lattice structure [34][35][36][37][38][39][40] and fluid systems [41]. In this paper we will concentrate on the influence of shear on a one-component colloidal crystal with a hexagonal lattice structure with and without misfit.…”