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

这个项目旨在研究技术上重要的氧化钇-氧化铝体系中的液体和无定形固体。这项工作包括充分表征两种具有相同成分但密度和其他热力学性质不同的液相之间的一种新型液-液相变。光谱学方法将用于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。以不同控制速率淬火或退火制备的一系列Y203-A1203组合物。将结合溶胶-凝胶合成、快速滚子淬火和空气动力学悬浮技术来制作低密度和高密度玻璃材料的样品。液-液相变在整个玻璃形成过程中引起了异常大的粘度变化，极大地影响了氧化钇-氧化铝液体的纤维拉拔特性。一个工业集团（无容器研究公司）正在对这种特性进行深入研究，他们将这种陶瓷纤维用于商业用途。这些已被证明具有高抗拉强度，在高温下与氧化铝相容，并表现出优异的抗蠕变性能。与CRI小组的合作是在我们之前的NSF探索性研究奖选定资助期间开始的。CRI将继续为结构表征提供样品。根据本合同进行的光谱和量热研究将使人们能够了解低密度和高密度液体和玻璃的结构性质及其特性。本文研究了激光主体晶体钇铝石榴石（YAG）的结晶行为。参与该项目的研究生和博士后将受益于研究这一科学和技术上的重要问题，并在该项目的合作阶段与CRI工业集团密切接触。这些关于氧化钇-氧化铝玻璃系统的研究不仅与激光主体晶体YAG的结晶行为有关，而且与这些系统中过冷熔体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处理方面具有重大潜力。

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.