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

9972509McKittrick光致发光是指在高能光子的激发下，从固体中发射光子(红外、可见光、紫外线)的过程。稀土活性氧化物(例如，掺Eu的氧化钇)是一种固体，当受到紫外光的轰击时会发出可见光。这些材料在信息显示、照明和闪烁体中有应用。温度或应力对发光强度、光谱能量分布(强度与波长的函数关系)和发光衰减率都有影响。以前量化这些效应的工作几乎完全是在单晶上完成的。技术上重要的材料，如多晶薄膜，还没有被研究过。更好地了解外界影响对薄膜发光性能的影响，对于这些材料有更广泛的工业应用是必要的。本项目的目标有两个：(1)确定理论预测的发光行为是否适用于稀土掺杂氧化钇单晶或多晶压片的实验值，作为温度和应力的函数；(2)识别和量化薄膜的温度、应力和微结构依赖的发光性能，并将这些值与以前获得的值进行比较。在这项研究中，我们将获得稀土激活氧化钇(和/或多晶氧化钇)单晶的发光性能随温度和应力的变化数据，并与现有的预测其发光行为的基本方程进行比较；制备薄膜，并与单晶的发光性能作为温度和应力的函数进行比较；量化晶界密度、位错密度、激活剂的偏析和颗粒尺寸对薄膜发光性能的影响；并基于包括温度、微结构特征和残余应力对薄膜稀土激活氧化钇发光性能的影响的基本方程，提供了一个模型和预测关系。发光固体用于许多消费应用中，其中最广为人知的是用作计算机显示屏的荧光粉。本项目将考察并试图了解这类材料的行为，以提高材料的效率，从而降低材料的成本。该项目将由两名研究人员实施，一名是发光材料专家，另一名是机械性能专家。

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.***