GOALI: Fluctuation Electron Microscopy Studies of Ultra-Low Expansion Glasses and Ceramics

GOALI：超低膨胀玻璃和陶瓷的涨落电子显微镜研究

• 批准号: 1906367
• 负责人: Michael Treacy
• 金额: $ 53.66万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1906367&HistoricalAwards=false
• 关键词: GOALI; Fluctuation; Electron; Microscopy; Studies

NON-TECHNICAL DESCRIPTION: High precision instruments and tools, such as space-telescope mirrors and stages in chip-fabrication chambers, are often subjected to large temperature changes and so they need to be made from materials that do not change size or shape with temperature. A family of ultra-low expansion materials (ULE) are produced by Corning Research and Development Corporation that meet these demanding requirements. They are a glassy mixture of titania and silica, but their precise structure and zero-expansion mechanism are not well understood. This research is investigating the ULE structures at the atomic level using a specialized microscope technique called fluctuation electron microscopy (FEM). FEM is a statistical technique that explores subtle traces of atomic ordering in otherwise disordered materials. There are two broad goals to the research. The first is to determine how the structure of the ULE materials change as a function of titania content and processing conditions, and to explain their low-expansion mechanism. The second is to develop the FEM technique into a fully quantitative tool for the study of all disordered materials, particularly glasses and amorphous ceramics. Aram Rezikyan of Corning Inc. is the industrial partner in this project; the PI and co-PI are joined by an additional industrial researcher who is conducting simulations. A graduate student is interacting closely with Corning and is learning instrumental and analytical skills that are valuable for a future career in materials science. High School students participate in this research during the year via a science-mentoring program (the SCENE program) run at Arizona State University. TECHNICAL DETAILS: An ultra-low expansion material (ULE) is made by Corning Research and Development Corporation as a solid solution of titania (TiO2) and silica (SiO2). The composition and processing conditions can be adjusted to give it a zero coefficient of thermal expansion (CTE) at a specified temperature. It is highly desirable to develop materials with a zero, or close to zero, rate of change of CTE over a wide range of temperatures. To achieve these properties, the detailed structure of the ULE glass-ceramic material must be determined, and the mechanism responsible for the zero expansion needs to be understood in detail. Because the material is a disordered glass, standard diffraction and imaging methods do not give a clear picture of the structure. In this project, fluctuation electron microscopy (FEM) is being used to detect and explore the medium-range order that is present at the 1- to 2-nm length scales in these otherwise long-range-disordered materials. There are two broad goals of this research. The first is to apply the FEM method to study the structure-property relationships of ULE TiO2 - SiO2 glass ceramics. The manner in which composition and medium-range order at length scales less than 2 nm affect properties is being examined. The second is to advance FEM as a quantitative technique for studying disordered materials, such as ceramics and glasses, by improving experimental and modeling protocols for investigating electron-beam-sensitive materials. A graduate student is developing high-level skills in many aspects of transmission electron microscopy, as well as developing FEM as a quantitative tool for studying glassy materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术描述：高精度仪器和工具，如太空望远镜的反射镜和芯片制造室中的载物台，经常受到大的温度变化的影响，因此它们需要由不随温度改变尺寸或形状的材料制成。康宁研发公司生产的一系列超低膨胀材料（ULE）可满足这些苛刻的要求。它们是二氧化钛和二氧化硅的玻璃状混合物，但它们的精确结构和零膨胀机制尚不清楚。这项研究是在原子水平上使用一种称为波动电子显微镜（FEM）的专门显微镜技术来研究ULE结构。FEM是一种统计技术，它可以探索原子在无序材料中有序的细微痕迹。这项研究有两个广泛的目标。首先是确定ULE材料的结构如何作为二氧化钛含量和加工条件的函数而变化，并解释其低膨胀机制。第二是将有限元技术发展成为一种完全定量的工具，用于研究所有无序材料，特别是玻璃和非晶陶瓷。康宁公司的Aram Rezikyan是该项目的工业合作伙伴; PI和co-PI由一名正在进行模拟的额外工业研究员加入。一名研究生正在与康宁密切互动，学习对材料科学未来职业生涯有价值的工具和分析技能。高中生在一年中通过亚利桑那州立大学的科学指导计划（SCENE计划）参与这项研究。技术规格：超低膨胀材料（ULE）由康宁研究与开发公司制成，为二氧化钛（TiO 2）和二氧化硅（SiO 2）的固溶体。可以调整组成和加工条件，使其在指定温度下具有零热膨胀系数（CTE）。非常希望开发在宽温度范围内CTE变化率为零或接近零的材料。为了实现这些性能，必须确定ULE玻璃陶瓷材料的详细结构，并且需要详细了解零膨胀的机制。由于该材料是一种无序的玻璃，标准的衍射和成像方法不能给出结构的清晰图像。在这个项目中，波动电子显微镜（FEM）被用来检测和探索中程秩序，这是目前在1至2纳米的长度尺度在这些否则长程无序材料。这项研究有两大目标。第一部分是应用有限元方法研究ULE TiO 2- SiO2微晶玻璃的结构与性能关系。正在研究的方式，其中的组合物和中程秩序在长度尺度小于2纳米的影响性能。第二是通过改进用于研究电子束敏感材料的实验和建模协议，将FEM作为研究无序材料（如陶瓷和玻璃）的定量技术。一名研究生正在发展透射电子显微镜多方面的高水平技能，以及开发FEM作为研究玻璃质材料的定量工具。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。