Glasses of dynamically asymmetric binary colloidal mixtures: Quiescent properties and dynamics under shear
Autor: | M. Paul Lettinga, Marco Laurati, Donald Guu, Tatjana Sentjabrskaja, Stefan U. Egelhaaf |
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Rok vydání: | 2013 |
Předmět: |
Materials science
media_common.quotation_subject FOS: Physical sciences Condensed Matter - Soft Condensed Matter Asymmetry Viscoelasticity Condensed Matter::Soft Condensed Matter Colloid Impurity Chemical physics Volume fraction Soft Condensed Matter (cond-mat.soft) SPHERES Anisotropy Elastic modulus binary mixtures dynamics glass structure viscoelasticity media_common |
Popis: | We investigate mixing effects on the glass state of binary colloidal hard-sphere-like mixtures with large size asymmetry, at a constant volume fraction phi = 0.61. The structure, dynamics and viscoelastic response as a function of mixing ratio reflect a transition between caging by one or the other component. The strongest effect of mixing is observed in systems dominated by caging of the large component. The possibility to pack a large number of small spheres in the free volume left by the large ones induces a pronounced deformation of the cage of the large spheres, which become increasingly delocalised. This results in faster dynamics and a strong reduction of the elastic modulus. When the relative volume fraction of small spheres exceeds that of large spheres, the small particles start to form their own cages, slowing down the dynamics and increasing the elastic modulus of the system. The large spheres become the minority and act as an impurity in the ordering beyond the first neighbour shell, i.e. the cage, and do not directly affect the particle organisation on the cage level. In such a system, when shear at constant rate is applied, melting of the glass is observed due to facilitated out-of-cage diffusion which is associated with structural anisotropy induced by shear. 8 pages, 7 figures, Proceedings of the 4th International Symposium on Slow Dynamics in Complex Systems, Sendai, 2-7 December 2012 |
Databáze: | OpenAIRE |
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