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Defects in Two Dimensional Colloidal Crystals
| Content Provider | Semantic Scholar |
|---|---|
| Author | Yu, Lichao |
| Copyright Year | 2015 |
| Abstract | of “ Defects in Two Dimensional Colloidal Crystals ” by Lichao Yu, Ph.D., Brown University, May 2015 We use digital video microscopy to study the defects in two-dimensional colloidal crystals (2DCC). A crystalline solid, different from its liquid state, preserves longwavelength shear rigidity and broken symmetry. Questions about how shear rigidity and long-range order disappear during melting, are unresolved in terms of the complication of defect structures and their roles in crystal melting, especially in two dimension. Colloidal crystals (CC) serve as a promising model system to directly observe the defects under optical microscope. In our first study, we report the effects of vacancies and interstitials on the phonon modes in a 2DCC. By applying the equipartition theorem, we extract the dispersion relation of the lattice vibrations using real-time video microscopy. We find that both longitudinal and transverse modes in the spectrum are softened by the existence of point defects. Second, we investigate the diffusion process of interstitials in a 2DCC. The motion is viewed as gliding of both edge dislocations along one of the crystalline axes. The microscopic process is equivalently a point mass overcoming Peierls barrier with an exponential escaping time. We also establish a new criterion to determine the ergodicity of a defect system and discover the nonergodic behavior of di-interstitials. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://repository.library.brown.edu/studio/item/bdr:419422/PDF/?embed=true |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
