Temperature, Stress and Microstructural Influences on the Luminescence Properties of Rare Earth Activated Yttrium Oxide

[9972509 . mckittrick]光致发光是光子（红外，可见光，紫外[UV]）在高能光子的激发下从固体发射出来的过程。稀土活化氧化物（例如，铕掺杂氧化钇）是一类固体，当受到紫外线光子轰击时，会发出可见光。这些材料在信息显示、照明和闪烁体中都有应用。温度或应力的施加对发光发射强度、光谱能量分布（强度随波长的变化）和发光衰减率均有影响。以前量化这些效应的工作几乎都是在单晶上完成的。技术上重要的材料，如多晶薄膜，还没有被研究过。为了使这些材料在工业上得到更广泛的应用，更好地了解外界因素对薄膜发光性能的影响是必要的。该项目的目标有两个：(1)确定理论预测的发光行为是否适用于在稀土掺杂氧化钇单晶或多晶致密材料上获得的实验值，作为温度和应力的函数；(2)确定和量化薄膜的温度、应力和微观结构相关的发光特性，并将这些值与之前获得的值进行比较。在本研究中，将获得稀土活化氧化钇单晶（和/或多晶氧化钇）的发光性能数据，并与现有的预测其行为的基本方程进行比较；将制备薄膜，并将其发光性能与单晶数据的温度和应力函数进行比较；研究了晶界密度、位错密度、活化剂偏析和晶粒尺寸对薄膜发光性能的影响；基于温度、微观结构特征和残余应力对薄膜稀土活化氧化钇发光性能影响的基本方程，提出了一个模型和预测关系。发光固体在许多消费应用中使用，其中最著名的是作为计算机显示屏的荧光粉。这个项目将检查并试图了解一类材料的行为，以提高效率，从而降低材料的成本。该项目将由两位研究人员进行，一位是发光材料方面的专家，另一位是机械性能方面的专家

9972509McKittrickPhotoluminescence is the process by which photons (infrared , visible, ultraviolet [UV]) are emitted from a solid under excitation by higher energy photons. Rare earth activated oxides (e.g., europium-doped yttrium oxide are a class of solids that emit visible light when bombarded with UV photons. These materials have application in information displays, lighting, and scintillators. The luminescence emission intensity, spectral energy distribution (intensity as a function of wavelength), and luminescence decay rate are influenced by the application of temperature or stress. Previous work on quantifying these effects has been done almost exclusively on single crystals. Technologically important materials, such as polycrystalline thin-films, have not been examined. A better understanding of the effect of external influences on the luminescence properties of thin- films is necessary for these materials to have more wide-spread industrial use. The objective of this project is twofold: (1) determine the applicability of theoretically predicted luminescence behavior to experimental values obtained on rare earth doped yttrium oxide single crystals or polycrystalline compacts as a function of temperature and stress and to (2) identify and quantify the temperature, stress and microstructure dependent luminescence properties of thin-films and compare these values to what was obtained previously. In the research, luminescence property data on single crystals of rare earth activated yttrium oxide (and/or polycrystalline yttrium oxide as a function of temperature and stress wil be obtained and compared with the currently available fundamental equations predicting the behavior; thin-films will be fabricated and the luminescence properties examined as compared with the single crystal data as a function of temperature and stress; the effect of grain boundary density, dislocation density, segregation of activators and grain size on the thin-film luminescence properties will be quantified; and a model and predictive relationships will be provided that are based on the fundamental equations that include the effect of temperature, microstructural features and residual stress on the luminescence properties of thin-film rare earth activated yttrium oxide. %%%Luminescent solids are used in many consumer applications, the most well known of these is as phosphors for computer display screens. This project will examine and try to understand the behavior of one class of these materials in order to increase the efficiently and thus decrease the cost of the materials. The project will be carried out by two researchers, one an expert in luminescent materials and one an expert in mechanical properties.***