Collective Structural Dynamics of Disordered Solids

9624436图卢兹该项目采用拉曼光谱和中子光谱作为研究玻璃网络拓扑结构的工具。 这项研究将研究从高温到低温的光谱特征的变化。 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，测试将由最近的几个理论的液体玻璃化转变的光谱预测。 由于成分或静水压力的强加变化，待研究的玻璃将具有不同的脆性参数。 该项目应导致更好地理解连接的拓扑结构之间的关系，随机网络，以及单个键的强度和振动动力学。 这项研究是基本的性质，但由于非晶和玻璃状材料的许多应用，其结果可能具有很大的实际意义。 无定形固体或玻璃由于其复杂的网络结构而成为研究的挑战性对象。 由于它们的许多商业应用，它们具有很大的实际意义。 玻璃具有许多不同于有序晶体的性质。 该项目将使用光谱技术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，并且因为玻璃是冷冻液体，所以从液体到玻璃状态的转变将作为温度的函数-从高温到低温。 这将有助于更好地理解无序网络的振动动力学。 这些结果应该对其他更普遍的无序网络具有普遍适用性，例如大脑或经济模型。 ***

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. ***