Structural aging of crystals of hard-sphere colloids.
Structural aging of crystals of hard-sphere colloids.
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硬球胶体晶体的结构老化。
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
P. Pusey
中科院分区：
文献类型：
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作者：
V. C. Martelozzo;A. Schofield;W. Poon;P. Pusey
我们报告了一个详细的实验研究的（初始）随机六方密堆积（rhcp）晶体在悬浮液中形成的硬球胶体的熔点附近的老化。通过将相同的胶体颗粒悬浮在两种不同的溶剂混合物中，我们能够调整作用在颗粒上的重力的强度。的晶体结构推导出由粉末X射线晶体学的光散射等效测量的衍射图案。在很长一段时间内观察到结构的自发老化，由一部分纯面心立方（fcc）晶体生长在随机堆叠的微晶为代价。新晶体的生长速率很小，与Pronk和Frenkel的预测一致[13]。重力也被揭示影响晶体和有利于fcc秩序，但通过一个缓慢的随机堆叠逐渐重排。一个重要的新观察是，小的机械扰动可以强烈影响胶体晶体的结构，促进面心立方生长和干扰自发老化过程。根据这些新的发现，以前的实验结果也进行了讨论。
We report a detailed experimental study of the aging of the (initial) random hexagonal close-packed (rhcp) crystals formed in suspensions of hard-sphere colloids near the melting point. By suspending the same colloidal particles in two different mixtures of solvents we are able to tune the strength of the gravitational forces acting on the particles. The crystal structure is deduced from diffraction patterns measured by the light scattering equivalent of powder x-ray crystallography. A spontaneous aging of the structure is observed over long periods of time, consisting of a fraction of pure face-centered cubic (fcc) crystals growing at the expense of the randomly stacked crystallites. The rate of growth of the new crystals is small and consistent with the predictions by Pronk and Frenkel [13]. Gravity is also revealed to affect the crystals and favor fcc order but through a slow gradual rearrangement of the random stacking. An important new observation is that small mechanical perturbations can strongly affect the structure of the colloidal crystals, promoting fcc growth and interfering with the spontaneous aging process. Previous experimental results are also discussed in the light of these new findings.