Phase Transformations in Crystalline Ceramic Oxides

该补助金是DMR-8521834的更新奖励， 高生产力：开发新的分析技术， 研究基本的相变和化学 两种不同的氧化物陶瓷在近原子 分辨率，开发使用卢瑟福背散射 光谱来确定这些反应的动力学 系统，并确认拓扑和外延生长， 这些材料一次出现在几个晶胞的层中 而不是像以前认为的那样一次一个原子层。 本工作的重点是利用这些新的分析 技术来理解结构的影响， 化学在相边界上的运动 两种不同晶体结构氧化物之间的界面。 使用的分析技术包括： 将使用透射电子显微镜（例如，化学 分析，原子晶格成像会聚束电子 衍射），电子显微探针，可见光显微镜， 卢瑟福背散射光谱和x射线衍射。 感兴趣的材料包括：镍铝氧化物尖晶石， 镁铝氧化物尖晶石、镁铬铝 氧化物尖晶石和铁铝氧化物尖晶石。 研究 有两个主要目标：界面的几何形状，以及 了解界面的形态和化学 影响界面发展的动力学。

This grant is a renewal award for DMR-8521834, which was highly productive: development of new analytical techniques to study the fundamental phase transformations and chemical reactions between two different oxide ceramics at near atomic resolution, development of the use of Rutherford backscattering spectroscopy to determine the kinetics of reactions in these systems, and confirmation that topotaxial and epitaxial growth in these materials occurs in layers of several unit cells at a time rather than one atomic layer at a time, as previously believed. The emphasis of this work is to use these new analytical techniques to understand the effect of the structure and chemistry at the phase boundary upon the movement of the interface between two oxides of different crystal structure. Analytical techniques being used include: all aspects of transmission electron microscopy will be used (e.g., chemical analysis, atomic lattice imaging. converging beam electron diffraction), electron microprobe, visible light microscopy, Rutherford backscattering spectroscopy, and x-ray diffraction. Materials if interest include: nickel-aluminum oxide spinels, magnesium-aluminum oxide spinels, magnesium-chromium-aluminum oxide speinels, and iron-aluminum oxide spinels. The research has two main objectives: geometry of the interface, and to understand how the morphology and the chemistry of the interface affect the kinetics with which the interface develops.