Grain boundary pinning in doped hard sphere crystals

Villeneuve, V.W.A. de; Derendorp, Leonie; Verboekend, Danny; Vermolen, Esther C. M.; Kegel, Willem K.; Lekkerkerker, H. N. W.; Dullens, Roel P. A.

doi:10.1039/b817255b

Cited by 24 publications

(20 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Comparing the total area to the defect area in front of the probe, shows that the defect area behind the probe dominates the observed total defect area, and hence, that the structure in front of the probe remains intact. Below the characteristic velocity v c the total defect area does not depend on the drag velocity, which yields a ''static defect area'' A 0 % 340 m 2 corresponding to an effective static defect probe radius L 0 % 10 m. This is consistent with a ''frustrated'' fluid layer of roughly one small particle diameter around the probe as reported for crystals containing large spherical impurities [26].…”

supporting

confidence: 79%

Shear Thinning and Local Melting of Colloidal Crystals

Dullens

Bechinger

2011

Phys. Rev. Lett.

Self Cite

View full text Add to dashboard Cite

Phenomena such as shear thinning and thickening, occurring when complex materials are exposed to external forces, are generally believed to be closely connected to changes in the microstructure. Here, we establish a direct and quantitative relation between shear thinning in a colloidal crystal and the surface area of the locally melted region by dragging a probe particle through the crystal using optical tweezing. We show that shear thinning originates from the nonlinear dependence of the locally melted surface area on the drag velocity. Our observations provide unprecedented quantitative evidence for the intimate relation between mechanical properties and underlying changes in microscopic structure. The response of materials to external stresses and strains is of central importance for many applications in science and technology [1,2]. At macroscopic length scales the microstructure of many materials and complex fluids is often neglected and continuum models are applied to describe their flow behavior [1][2][3]. As a consequence of progressive miniaturization, the effect of the microscopic structure on mechanical properties becomes increasingly significant, which has invoked the development of micromechanical models [3][4][5][6]. Also in complex fluids there are many suggestions that the rearrangement of the local structure is the basis for behavior like shear thickening and thinning [1,2,[7][8][9][10]. The key here is the simultaneous characterization of the external forces and changes in the microstructure. We achieve this using active microrheology of colloidal crystals, which enables us to directly connect shear thinning to local melting.A two-dimensional, hexagonal colloidal crystal of melamine spheres of radius R c ¼ 1:5 m in water is deformed using a probe particle trapped in an optical tweezer. The lattice spacing a and number density are 3:5 m and 0:087 m À2 respectively, and the size of singledomain crystallites is typically larger than 250 Â 250 m 2 . Adding a very small amount (less than one probe particle per $3000 small particles) of large polystyrene probe particles (R p ¼ 7:75 m) to the suspension results in a crystal with built-in probe particles as shown in Fig.

show abstract

supporting

confidence: 79%

Shear Thinning and Local Melting of Colloidal Crystals

Dullens

Bechinger

2011

Phys. Rev. Lett.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Previous investigation has focused on the effect of impurities that are either much larger [14,15,23] or much smaller [24] than their host colloids on crystallisation in three dimensions. These studies demonstrate that the texture of a colloidal polycrystal can be controlled through suitable choice of impurity size and concentration.…”

Section: Introductionmentioning

confidence: 99%

Structural characterisation of polycrystalline colloidal monolayers in the presence of aspherical impurities

Gray

Mould

Royall

et al. 2015

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

Abstract.Impurities in crystalline materials introduce disorder into an otherwise ordered structure due to the formation of lattice defects and grain boundaries. The properties of the resulting polycrystal can differ remarkably from those of the ideal single crystal.Here we investigate a quasi-two-dimensional system of colloidal spheres containing a small fraction of aspherical impurities and characterise the resulting polycrystalline monolayer. We find that, in the vicinity of an impurity, the underlying hexagonal lattice is deformed due to a preference for 5-fold co-ordinated particles adjacent to impurities. This results in a reduction in local hexagonal ordering around an impurity. Increasing the concentration of impurities leads to an increase in the number of these defects and consequently a reduction in system-wide hexagonal ordering and a corresponding increase in entropy as measured from the distribution of Voronoi cell areas.Furthermore, through both considering orientational correlations and directly identifying crystalline domains we observe a decrease in the average polycrystalline grain size on increasing the concentration of impurities.Our data show that, for the concentrations considered, local structural modifications due to the presence of impurities are independent of their concentration, while structure on longer lengthscales (i.e the size of polycrystalline grains) is determined by the impurity concentration.arXiv:1407.8490v2 [cond-mat.soft]

show abstract

“…Scientists have developed numerous protocols to control the average grain size in a colloidal polycrystal. These include changing the inter particle interactions [106], applying external electric fields or shear deformations [106][107][108], adding impurities [109][110][111][112] and by changing the cooling rate in a thermoresponsive colloidal system [108]. The melting of crystals has been studied extensively using colloids.…”

Section: Summary Of Condensed Matter Problems Addressed Using Colloidsmentioning

confidence: 99%

Deconstructing the glass transition through critical experiments on colloids

Gokhale

Sood

Ganapathy

2016

Advances in Physics

View full text Add to dashboard Cite

The glass transition is the most enduring grand-challenge problem in contemporary condensed matter physics. Here, we review the contribution of colloid experiments to our understanding of this problem. First, we briefly outline the success of colloidal systems in yielding microscopic insights into a wide range of condensed matter phenomena. In the context of the glass transition, we demonstrate their utility in revealing the nature of spatial and temporal dynamical heterogeneity.We then discuss the evidence from colloid experiments in favor of various theories of glass formation that has accumulated over the last two decades. In the next section, we expound on the recent paradigm shift in colloid experiments from an exploratory approach to a critical one aimed at distinguishing between predictions of competing frameworks. We demonstrate how this critical approach is aided by the discovery of novel dynamical crossovers within the range accessible to colloid experiments. We also highlight the impact of alternate routes to glass formation such as random pinning, trajectory space phase transitions and replica coupling on current and future research on the glass transition. We conclude our review by listing some key open challenges in glass physics such as the comparison of growing static lengthscales and the preparation of ultrastable glasses, that can be addressed using colloid experiments.

show abstract

Grain boundary pinning in doped hard sphere crystals

Cited by 24 publications

References 30 publications

Shear Thinning and Local Melting of Colloidal Crystals

Shear Thinning and Local Melting of Colloidal Crystals

Structural characterisation of polycrystalline colloidal monolayers in the presence of aspherical impurities

Deconstructing the glass transition through critical experiments on colloids

Contact Info

Product

Resources

About