Phase transformations in binary colloidal monolayers.
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Phase transformations can be difficult to characterize at the microscopic level due to the inability to directly observe individual atomic motions. Model colloidal systems, by contrast, permit the direct observation of individual particle dynamics and of collective rearrangements, which allows for real-space characterization of phase transitions. Here, we study a quasi-two-dimensional, binary colloidal alloy that exhibits liquid-solid and solid-solid phase transitions, focusing on the kinetics of a diffusionless transformation between two crystal phases. Experiments are conducted on a monolayer of magnetic and nonmagnetic spheres suspended in a thin layer of ferrofluid and exposed to a tunable magnetic field. A theoretical model of hard spheres with point dipoles at their centers is used to guide the choice of experimental parameters and characterize the underlying materials physics. When the applied field is normal to the fluid layer, a checkerboard crystal forms; when the angle between the field and the normal is sufficiently large, a striped crystal assembles. As the field is slowly tilted away from the normal, we find that the transformation pathway between the two phases depends strongly on crystal orientation, field strength, and degree of confinement of the monolayer. In some cases, the pathway occurs by smooth magnetostrictive shear, while in others it involves the sudden formation of martensitic plates.
Published Version (Please cite this version)10.1039/c5sm00009b
Publication InfoCharbonneau, Patrick; Fu, L; Marcoux, C; Socolar, Joshua ES; Yang, Y; & Yellen, Benjamin (2015). Phase transformations in binary colloidal monolayers. Soft Matter, 11(12). pp. 2404-2415. 10.1039/c5sm00009b. Retrieved from https://hdl.handle.net/10161/12618.
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Associate Professor of Chemistry
Professor Charbonneau studies soft matter. His work combines theory and simulation to understand the glass problem, protein crystallization, microphase formation, and colloidal assembly in external fields.
Associate Professor in the Department of Mechanical Engineering and Materials Science
Yellen's group is interested in developing highly parallel mechanisms for controlling the transport and assembly of ensembles of objects ranging from micron-sized colloidal particles to single cells. As of 2013, Professor Yellen is active in two main areas of research:1) Development of single cell analysis tools using magnetic circuits. The goal of this project is to develop an automated single cell analysis platform that allows for highly flexible and highly paralle
Alphabetical list of authors with Scholars@Duke profiles.