Sun, 27 Jul 2008 08:04:10 BST CiteULike: dchen's schall http://www.citeulike.org/user/dchen/tag/schall CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/dchen/article/2746695 <i>(2006)</i> Dynamics of dislocations in thin colloidal crystals Cohen Schall Weitz (2006) 2008-05-02T17:54:23-00:00 2006 cohen colloid defect schall weitz http://www.citeulike.org/user/dchen/article/2710365 <i>Science, Vol. 305, No. 5692. (24 September 2004), pp. 1944-1948.</i><br /><br />The dominant mechanism for creating large irreversible strain in atomic crystals is the motion of dislocations, a class of line defects in the crystalline lattice. Here we show that the motion of dislocations can also be observed in strained colloidal crystals, allowing detailed investigation of their topology and propagation. We describe a laser diffraction microscopy setup used to study the growth and structure of misfit dislocations in colloidal crystalline films. Complementary microscopic information at the single-particle level is obtained with a laser scanning confocal microscope. The combination of these two techniques enables us to study dislocations over a range of length scales, allowing us to determine important parameters of misfit dislocations such as critical film thickness, dislocation density, Burgers vector, and lattice resistance to dislocation motion. We identify the observed dislocations as Shockley partials that bound stacking faults of vanishing energy. Remarkably, we find that even on the scale of a few lattice vectors, the dislocation behavior is well described by the continuum approach commonly used to describe dislocations in atomic crystals. 10.1126/science.1102186 Visualization of Dislocation Dynamics in Colloidal Crystals Peter Schall Itai Cohen David Weitz Frans Spaepen doi:10.1126/science.1102186 Science, Vol. 305, No. 5692. (24 September 2004), pp. 1944-1948. 2008-04-23T22:01:50-00:00 2004 Science 305 5692 1944 1948 cohen schall science shear weitz http://www.citeulike.org/user/dchen/article/553502 <i>Nature, Vol. 440, No. 7082., pp. 319-323.</i> Visualizing dislocation nucleation by indenting colloidal crystals Peter Schall Itai Cohen David Weitz Frans Spaepen doi:10.1038/nature04557 Nature, Vol. 440, No. 7082., pp. 319-323. 2006-03-15T23:36:35-00:00 Nature 0028-0836 440 7082 319 323 Nature Publishing Group defect schall shear weitz http://www.citeulike.org/user/dchen/article/2453811 <i>Science, Vol. 318, No. 5858. (21 December 2007), pp. 1895-1899.</i><br /><br />Structural rearrangements are an essential property of atomic and molecular glasses; they are critical in controlling resistance to flow and are central to the evolution of many properties of glasses, such as their heat capacity and dielectric constant. Despite their importance, these rearrangements cannot directly be visualized in atomic glasses. We used a colloidal glass to obtain direct three-dimensional images of thermally induced structural rearrangements in the presence of an applied shear. We identified localized irreversible shear transformation zones and determined their formation energy and topology. A transformation favored successive ones in its vicinity. Using continuum models, we elucidated the interplay between applied strain and thermal fluctuations that governs the formation of these zones in both colloidal and molecular glasses. 10.1126/science.1149308 Structural Rearrangements That Govern Flow in Colloidal Glasses Peter Schall David Weitz Frans Spaepen doi:10.1126/science.1149308 Science, Vol. 318, No. 5858. (21 December 2007), pp. 1895-1899. 2008-03-01T21:29:01-00:00 2007 Science 318 5858 1895 1899 colloids flow schall shear stz weitz