Neutron and X-ray studies of the structure and relaxation in high temperature levitated liquids and glasses.

氧化玻璃在我们周围无处不在，被广泛用于窗户玻璃、激光材料和电子工业中使用的基板等各种应用中。尽管有这么多的应用，但令人惊讶的是，其中一些材料的真正理解程度是如此之低。近年来，由氧化铝与其他金属氧化物（金属铝酸盐）的混合物制成的高温玻璃揭示了新的有趣的物理现象。值得注意的是，同一材料的两个液相可以在相同的温度下共存（所谓的液-液相变），并从这种状态生产出多晶玻璃（即在室温下生产两种混合玻璃）。观察液-液转变尤其具有挑战性（它也被预测存在于纯水中），理论上难以理解。这项工作的一个目的是为这种新的令人惊讶的行为提供新的线索。稀土铝酸盐的光学特性，特别是发光性能，对于下一代显示器或激光材料的使用也很有兴趣。然而，这些玻璃的发光效率在很大程度上取决于玻璃的生产方式。这项工作的第二个目的是了解这些玻璃中活性离子周围的局部结构如何根据其热历史而变化，以及这与其性质之间的关系。最后，玻璃化转变本身仍然是凝聚态物理中最难以理解的现象之一。在这些铝酸盐玻璃中观察到的玻璃化时间尺度使它们成为通过结构测量（衍射）和弛豫测量（非弹性散射）研究过冷液体形成玻璃的良好材料。我们打算应用这些方法来更好地理解这些液体中产生玻璃形成、相分离和结晶的性质。

Oxide glasses are ubiquitous in the world around us and are used in a wide variety of applications from window glass, laser materials and the substrates used in the electronics industry. Despite this multitude of applications it is surprising how poorly some of these materials are really understood. Recently, high temperature glasses produced from mixtures of Aluminium Oxide with other Metal oxides (metal aluminates) have revealed new and interesting physical phenomema. This is notably the production of a state where two liquid phases of the same material can co-exist at the same temperature (the so-called liquid-liquid phase transition) and the production of poly-amorphic glasses (i.e. the production of two intermixed glasses at room temperature) from this state. The liquid-liquid transition is particularly challenging to observe (it has also been predicted to exist in pure water) and theoretically difficult to understand. An aim of this work is to throw new light on this new a surprising behaviour. The optical properties and in particular, luminescence from rare-earth aluminates are also of interest either for use in next generation displays or as materials for lasers. However, the efficiency of the luminescence of these glasses is strongly dependent on the way in which the glasses are produced. A second aim of this work is to understand how the local structure around the active ion in these glasses changes according to its thermal history and how this can be related to its properties. Finally, the glass transition itself remains one of the most poorly understood phenmomena in condensed matter physics. The timescales for vitrification observed in these aluminate glasses make them good materials in which to study the glass formation from the supercooled liquid by both structure measurements (diffraction) and relaxation measurements (inelastic scattering). We intend to apply these methods to understand better the properties that give rise to glass formation, phase separation and crystallization in these liquids.