Phonons in two-dimensional colloidal crystals with bond-strength disorder
| Autor: | Peter Yunker, Arjun G. Yodh, Tim Still, Kevin B. Aptowicz, Ke Chen, Matthew Gratale |
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| Rok vydání: | 2013 |
| Předmět: |
Models
Molecular Binding Sites Materials science Condensed matter physics Dopant Bond strength Phonon Video microscopy Colloidal crystal Vibration Models Chemical Condensed Matter::Superconductivity Density of states Polystyrenes Quantum Theory Particle Computer Simulation Hexagonal lattice Colloids Crystallization Rheology |
| Zdroj: | Physical Review E. 87 |
| ISSN: | 1550-2376 1539-3755 |
| DOI: | 10.1103/physreve.87.052301 |
| Popis: | We study phonon modes in two-dimensional colloidal crystals composed of soft microgel particles with hard polystyrene particle dopants distributed randomly on the triangular lattice. This experimental approach produces close-packed lattices of spheres with random bond strength disorder, i.e., the effective springs coupling nearest neighbors are very stiff, very soft, or of intermediate stiffness. Particle tracking video microscopy and covariance matrix techniques are then employed to derive the phonon modes of the corresponding "shadow" crystals with bond strength disorder as a function of increasing dopant concentration. At low frequencies, hard and soft particles participate equally in the phonon modes, and the samples exhibit Debye-like density of states behavior characteristic of crystals. For mid- and high-frequency phonons, the relative participation of hard versus soft particles in each mode is found to vary systematically with dopant concentration. Additionally, a few localized modes, primarily associated with hard particle motions, are found at the highest frequencies. |
| Databáze: | OpenAIRE |
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