Collective Structural Dynamics of Disordered Solids

9624436图卢兹这个项目使用拉曼光谱学和中子光谱学作为研究玻璃网络拓扑的工具。这项研究将研究光谱特征从高温到低温的变化。特别令人感兴趣的是在较低温度下的低频动力学的开始。此外，还将对最近几种液体-玻璃转变理论的光谱预测进行测试。由于组成的不同或静水压力的变化，被研究的玻璃将具有不同的脆性参数。该项目应该会导致更好地理解连接的随机网络的拓扑结构与单个键的强度和振动动力学之间的关系。这项研究在性质上是基础性的，但由于非晶态和类玻璃材料的许多应用，其结果可能具有极大的实用价值。%无定形固体或玻璃由于其复杂的网络结构而成为具有挑战性的研究对象。由于它们的许多商业应用，它们具有很大的实用价值。玻璃具有许多不同于有序晶体的性质。这个项目将使用光谱技术来研究玻璃的低频振动特性，并将这些测量与材料的结构构象联系起来。因为玻璃的原子结构是在高温下形成的，而且玻璃是冻结的液体，所以从液体到玻璃态的转变将随着温度的变化而发生--从高温到低温。这应该有助于更好地理解无序网络的振动动力学。这些结果应该普遍适用于其他更普遍的无序网络，如大脑或经济模型中开发的网络。***

9624436 Toulouse This project employs Raman optical spectroscopy and neutron spectroscopy as tools for the study of network topologies in glasses. The research will study the variation of spectroscopic signatures from high temperatures to low temperatures. Of particular interest is the onset of low frequency dynamics at lower temperatures. In addition, tests will be made of the spectroscopic predictions of several recent theories of the liquid-glass transition. The glasses to be studied will have different fragility parameters because of composition or as a result of imposed variations in hydrostatic pressure. The project should lead to a better understanding of the relationship between the topology of connected, random networks, and the strength of individual bonds and vibrational dynamics. The research is fundamental in character but the results are potentially of great practical interest because of the many applications of amorphous and glass-like materials. %%% Amorphous solids or glasses are challenging objects for study because of their complex network structures. They are of great practical interest because of their many commercial applications. Glasses have many properties that differ from those of ordered crystals. This project will use spectroscopic techniques to study the low frequency vibrational properties of glasses and to relate these measurements to the structural conformation of the materials. Because the atomic structure of the glass is formed at high temperatures and because the glass is a frozen liquid, the transition from the liquid to the glass state will be followed as a function of temperature - from high temperature to low temperatures. This should lead to a better understanding of the vibrational dynamics of disordered networks. The results should have general applicability to other more general disordered networks such as the brain or as developed in economic models. ***