Rotational and translational phonon modes in glasses composed of ellipsoidal particles.
Rotational and translational phonon modes in glasses composed of ellipsoidal particles.
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DOI：
10.1103/physreve.83.011403
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发表时间：
2010-12
期刊：
影响因子：
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通讯作者：
P. Yunker;Ke Chen;Zexin Zhang;W. G. Ellenbroek;Andrea J. Liu;A. G. Yodh
中科院分区：
文献类型：
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作者：
P. Yunker;Ke Chen;Zexin Zhang;W. G. Ellenbroek;Andrea J. Liu;A. G. Yodh
实验研究了颗粒形状对胶体玻璃振动性能的影响。“椭球玻璃”是通过将聚苯乙烯球体拉伸到不同的长宽比，然后将产生的椭球粒子以高填充分数悬浮在水中而产生的。通过测量粒子之间的位移关联，我们提取了与源悬浮体相同的几何构型和相互作用但没有阻尼的相应的阴影椭球玻璃的振动特性。观察到由长、短轴长宽比为~1.1的椭球粒子组成的玻璃中的低频模式具有明显的旋转特性。相反，长宽比较大(~3.0)的椭球粒子玻璃中的低频模式表现出旋转和平移混合的特征。用不同长宽比的颗粒分布对所有玻璃样品进行了表征。有趣的是，即使在同一样本中，也发现小长宽比粒子相对更多地参与旋转模式，而大长宽比粒子往往相对更多地参与平移模式。
The effects of particle shape on the vibrational properties of colloidal glasses are studied experimentally. "Ellipsoidal glasses" are created by stretching polystyrene spheres to different aspect ratios and then suspending the resulting ellipsoidal particles in water at a high packing fraction. By measuring displacement correlations between particles, we extract vibrational properties of the corresponding "shadow" ellipsoidal glass with the same geometric configuration and interactions as the "source" suspension but without damping. Low-frequency modes in glasses composed of ellipsoidal particles with major-to-minor axis aspect ratios of ~1.1 are observed to have predominantly rotational character. In contrast, low-frequency modes in glasses of ellipsoidal particles with larger aspect ratios (~3.0) exhibit a mixed rotational and translational character. All glass samples were characterized by a distribution of particles with different aspect ratios. Interestingly, even within the same sample it was found that small-aspect-ratio particles participate relatively more in rotational modes, while large-aspect-ratio particles tend to participate relatively more in translational modes.