High- and Low-Density Glasses and Liquids in the Yttrium Oxide - Aluminum Oxide System

9818133 McMillan该项目旨在研究技术上重要的氧化钇-氧化铝系统中的液体和无定形固体。这项工作涉及充分表征一种新型的液-液相变之间的两个液相具有相同的组成，但具有不同的密度和其他热力学性质。光谱方法将被用来研究玻璃的结构性质，以及过冷液体和玻璃的机械和热力学性质。通过在不同的受控速率下淬火或退火制备的一系列Y2 O3-Al 2 O3组合物。溶胶-凝胶合成技术，快速辊淬火，空气动力悬浮，将结合起来，使样品的低和高密度的玻璃质材料。液-液相变导致在整个玻璃形成范围内异常大的粘度变化，这极大地影响了氧化钇-氧化铝液体的拉纤特性。一个工业集团（无容器研究公司）正在对这一特性进行深入研究，他们有陶瓷纤维的商业应用。这些已被证明具有高拉伸强度，在高温下与氧化铝相容，并表现出优异的抗蠕变性。与CRI小组的合作是在我们之前的NSF探索性研究奖选定补助金期间开始的。CRI将继续提供用于结构表征的样品。根据本合同进行的光谱和量热研究将有助于了解低密度和高密度液体和玻璃的结构性质及其性质。这项研究是有关的结晶行为的激光基质晶体钇铝石榴石（YAG）。参与该项目的研究生和博士后助理将受益于对这一科学和技术重要问题的研究，并在该项目的合作阶段与CRI工业集团密切联系。氧化钇-氧化铝玻璃体系的这些研究不仅与激光基质晶体YAG的结晶行为有关，而且与从这些体系中的过冷熔体中拉出的纤维的形成有关。该项目在优化用于光纤数据传输的材料加工方面具有巨大潜力。

9818133 McMillan This project aims to study liquids and amorphous solids in the technologically important system yttrium oxide - aluminum oxide. The work involves fully characterizing a new type of liquid-liquid phase transition between two liquid phases with the same composition, but with different densities and other thermodynamic properties. Spectroscopic methods will be utilized to study the structural nature of the glasses, as well as the mechanical and thermodynamic properties of the supercooled liquids and glasses. A range of Y203-A1203 compositions prepared by quenching or annealing at different controlled rates. Techniques of sol-gel synthesis, rapid roller quenching, and aerodynamic levitation, will be combined to make samples of low- and high-density glassy materials. The liquid-liquid phase transition causes an unusually large viscosity change throughout the glass-forming range, which greatly affects the fiber-pulling characteristics of yttria-alumina liquids. This property is under intense study by an industrial group (Containerless Research Inc.), who have commercial applications for the ceramic fibers. These have been shown to possess high tensile strength, are compatible with alumina at high temperature, and exhibit excellent creep resistance. Collaboration with the CRI group was initiated during our prior NSF Selected Grant for Exploratory Research award. CRI will continue to supply samples for structural characterization. The spectroscopic and calorimetric studies to be carried out under the present award will permit understanding of the structural nature of the low- and high-density liquids and glasses and their properties. This study is relevant to the crystallization behaviour of the laser host crystal yttrium aluminium garnet (YAG). The graduate student and post-doctoral associate involved in the project will benefit from working on this scientifically and technologically important problem, in close contact with the CRI industrial group during the collaborative phase of this project.%%%These studies on yttrium oxide - aluminum oxide glassy systems are relevant not only to the crystallization behavior of the laser host crystal YAG, but also to the formation of fibres pulled from undercooled melts in these systems. The project has significant potential for optimizing the processing of materials used in fiber-optics data transmission.