Nanocrystalline Alumina and Titania under High Pressure and Temperature

高压高温下的纳米晶氧化铝和二氧化钛

• 批准号: 0605493
• 负责人: Michael Kruger
• 金额: $ 41.64万
• 依托单位: University of Missouri-Kansas City
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-06-01 至 2011-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0605493&HistoricalAwards=false
• 关键词: Nanocrystalline; Alumina; Titania; under; Pressure

NON-TECHNICAL DESCRIPTION Nanocrystalline materials, materials that are smaller than light waves, have become of great scientific interest, due to interesting physics and their related technological impact. For example, nanocrystals are a key component of bone and teeth, they are used in drug delivery systems and various other technologies, and their uses will become increasingly widespread. To gain a better understanding of these materials, the principal investigator will study two important ceramics, alumina and titania, by subjecting them to high pressures and high temperatures. Application of such extreme conditions can significantly alter a material's structure. For example, it is through high pressure and temperature that more than 100 tons of graphite are converted into diamond each year. In this work, the reaction of the nanocrystalline ceramics to high pressure and temperature will studied, in order to obtain a better understanding of nanocrystalline materials in general and possibly to create new, useful materials. Researchers in the high-pressure lab will work with the staff at Science City, Kansas City's Science Museum, to bring high-pressure physics to the public. A remote-controlled, high-pressure rig will be installed and loaded with liquid water. Patrons will be able to vary the pressure, and observe that when subjected to high pressure (nine thousand times atmospheric pressure) liquid water solidifies, becoming ice. This process is reversible and can be repeated. A computerized presentation will run concurrently to explain what is going on and also other aspects of high-pressure physics. TECHNICAL DETAILS Synchrotron based x-ray diffraction, Raman spectroscopy, fluorescence spectroscopy and transmission electron microscopy will be used to study the effects of high pressures and temperatures on nanocrystalline samples of alumina and titania. Grain growth, changes in local bonding, the phase diagrams, the kinetics of phase transitions and the elastic properties of these ceramics, will be explored as functions of particle size, pressure, pressure-transmitting medium and temperature. It is clear that the properties of a nanocrystal, even its structure, can be very different from the bulk crystal and also sensitive to the particle's size and environment. Thus changes in the above listed parameters will profoundly affect the nanocrystals and allow for a deep understanding of the smallest of crystals. The variation of the compressibility of alumina with particle size (~150 GPa at 6 nm and ~240 GPa at 67 nm) is just one example of how rich a field of study nanoparticle research is. The proposed research will further the possibilities of tuning a material's properties to fit different technological needs while also opening opportunities of creating new, technologically useful materials. Graduate students will be trained in the use of all of the above-mentioned techniques, giving them the ability to fully characterize materials. Graduate students will also get training in communicating the results of science to the public, through a collaboration with Science City, Kansas City's science museum. In this collaboration, the high-pressure group will install a remote controlled diamond anvil cell to demonstrate pressure-induced freezing and melting of water.

纳米晶体材料是一种比光波还小的材料，由于其有趣的物理学和相关的技术影响，纳米晶体材料已经引起了人们极大的科学兴趣。例如，纳米晶体是骨骼和牙齿的关键组成部分，它们被用于药物输送系统和各种其他技术，并且它们的用途将变得越来越广泛。为了更好地了解这些材料，首席研究员将研究两种重要的陶瓷，氧化铝和二氧化钛，将它们置于高压和高温下。这种极端条件的应用会显著改变材料的结构。例如，每年有超过100吨的石墨通过高压和高温转化为钻石。在这项工作中，将研究纳米晶陶瓷对高压和高温的反应，以便更好地了解纳米晶材料的一般情况，并可能创造新的有用的材料。高压实验室的研究人员将与堪萨斯城科学博物馆科学城的工作人员合作，将高压物理学带给公众。一个远程控制的高压钻井平台将被安装并装载液态水。顾客可以改变压力，并观察到当受到高压（9000倍大气压）时，液态水凝固，变成冰。这个过程是可逆的，可以重复。计算机演示将同时进行，以解释正在发生的事情以及高压物理的其他方面。基于同步加速器的x射线衍射、拉曼光谱、荧光光谱和透射电子显微镜将用于研究高压和温度对氧化铝和二氧化钛纳米晶样品的影响。晶粒生长、局部键合的变化、相图、相变动力学和这些陶瓷的弹性性能，将作为粒径、压力、传压介质和温度的函数进行探索。很明显，纳米晶体的特性，甚至它的结构，可能与大块晶体有很大的不同，而且对粒子的大小和环境也很敏感。因此，上述参数的变化将深刻地影响纳米晶体，并允许对最小晶体的深入了解。氧化铝的可压缩性随粒径的变化（在6纳米处约150 GPa，在67纳米处约240 GPa）只是纳米颗粒研究领域多么丰富的一个例子。拟议的研究将进一步调整材料特性以适应不同技术需求的可能性，同时也为创造新的、技术上有用的材料提供了机会。研究生将接受使用上述所有技术的培训，使他们能够充分表征材料。研究生还将通过与堪萨斯城科学博物馆科学城的合作，获得向公众传播科学成果的培训。在这次合作中，高压小组将安装一个远程控制的钻石砧细胞来演示压力引起的水的冻结和融化。