Microscopic ergodicity breaking governs the emergence and evolution of elasticity in glass-forming nanoclay suspensions
Microscopic ergodicity breaking governs the emergence and evolution of elasticity in glass-forming nanoclay suspensions
复制标题
微观遍历性破坏控制玻璃形成纳米粘土悬浮液中弹性的出现和演变
DOI：
10.1103/physreve.102.042619
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发表时间：
2020
影响因子：
2.4
通讯作者：
Leheny, Robert L.
中科院分区：
文献类型：
--
作者：
Chen, Yihao;Rogers, Simon A.;Narayanan, Suresh;Harden, James L.;Leheny, Robert L.
我们报告了一项研究，结合x射线光子相关光谱（XPCS）siturheology调查合成锂蒙脱石粘土Laponite，这是由带电的，纳米尺度，盘形颗粒的水悬浮液的微观动力学和力学性能。颗粒浓度范围为3.25至3.75重量%的悬浮液随时间从流体演变为显示老化行为的软玻璃。XPCS测量表征了软玻璃态形成和老化过程中颗粒的局部化。局部化粒子的分数，在早期形成阶段迅速增加，并在随后的老化过程中增长缓慢，而特征局部化长度稳步下降。尽管在不同浓度下老化速率变化很大，但两者都以独立于浓度的方式与弹性剪切模量成比例。在后期老化阶段，之间的标度和同意定量与朴素模式耦合理论的预测。在早期形成阶段与理论的协议的故障表明的流行动态异质性，表明软固体形式通过动态本地化集群的前体。
We report a study combining x-ray photon correlation spectroscopy (XPCS) within siturheology to investigate the microscopic dynamics and mechanical properties of aqueous suspensions of the synthetic hectorite clay Laponite, which is composed of charged, nanometer-scale, disk-shaped particles. The suspensions, with particle concentrations ranging from 3.25 to 3.75 wt %, evolve over time from a fluid to a soft glass that displays aging behavior. The XPCS measurements characterize the localization of the particles during the formation and aging of the soft-glass state. The fraction of localized particles,, increases rapidly during the early formation stage and grows more slowly during subsequent aging, while the characteristic localization lengthsteadily decreases. Despite the strongly varying rates of aging at different concentrations, bothandscale with the elastic shear modulusin a manner independent of concentration. During the later aging stage, the scaling betweenandagrees quantitatively with a prediction of naive mode coupling theory. Breakdown of agreement with the theory during the early formation stage indicates the prevalence of dynamic heterogeneity, suggesting the soft solid forms through precursors of dynamically localized clusters.