Nanotechnology: Preparation, Characterization, and Dynamical Properties of Nanostructured Metal-Oxide Materials

9871864组织将对掺杂镧系金属氧化物纳米结构的物理、光学和动力学性质进行系统而广泛的研究。这些新型材料有潜在的应用前景，可以作为激光和光学放大器的材料，也可以作为平板显示器的荧光粉。这项工作将有助于建立一个理论和实践框架，以优化金属氧化物纳米晶体和纳米复合材料的光学性能。微米尺寸材料的颗粒尺寸的减小通常会由于表面缺陷的淬火而导致光学发射的减少。实验表明，纳米晶体的有限尺寸效应可以显著提高杂质跃迁的振荡强度。此外，对声子态密度和电子-声子相互作用强度的修改无疑会影响纳米粒子系统中的非辐射弛豫率。显示行业的应用要求高分辨率和低电压平板显示器的颗粒尺寸更小。同时，它们还需要坚固耐用和高效的材料。因此，纳米晶体的光学和动力学性质将被单独表征，以及通过表面改性或嵌入基体钝化后的光学和动力学性质。该方法将是制备纳米结构材料，并在弗吉尼亚理工大学通过x射线衍射、透射电子显微镜、原子力显微镜和荧光光谱学表征其结构和形态。然后，佐治亚大学将使用高分辨率光谱技术对表征良好的纳米结构材料进行研究，以确定振荡器强度、光学减相、非辐射松弛、声子动力学和能量传递过程取决于粒子大小或表面修饰。弗吉尼亚理工大学和佐治亚大学之间的合作汇集了纳米晶体合成、加工和表征方面的专业知识，以及高分辨率和非线性光谱技术方面的专业知识。合成组和光谱学组之间的密切合作将允许pi系统地生长和表征新材料，性能测量提供快速反馈，指导材料的制备和加工。这种合作的协同作用将使在制备和理解非常复杂的纳米结构方面取得比小组单独工作更大的进展%%%新型镧系掺杂金属氧化物纳米结构材料在激光和光学放大器材料以及平板显示器荧光粉方面具有潜在的应用前景。这项研究的结果将为工程纳米结构提供反馈，以改善这些材料的性能。弗吉尼亚理工大学和佐治亚大学之间跨学科性质的合作将为培养未来的科学家提供良好的教育经验，以适应科学研究和技术发展日益突出的多学科团队合作。该项目是纳米技术计划的一部分，由材料研究部的陶瓷和固态化学项目、电气和通信系统部的物理基础和使能技术项目以及数学和物理科学理事会的多学科活动办公室资助。此外，国际项目司还为pi与俄罗斯同行进行合作研究提供旅费。

9871864 Tissue A systematic and extensive study of the physical, optical, and dynamical properties of lanthanide-doped metal-oxide nanostructures will be performed. These novel materials have potential applications as materials for lasers and optical amplifiers, and as phosphors for flat-panel displays. This work will assist in developing a theoretical and practical framework to optimize the optical properties of metal-oxide nanocrystals and nanocomposites. A reduction in particle size for micron-size materials has often resulted in a reduction in optical emission due to quenching by surface defects. There are experimental indications that finite size effects in nanocrystals can significantly enhance the oscillator strength of impurity transitions. In addition, modifications to the phonon density-of-states, and to the strength of the electron-phonon interaction, will undoubtedly influence non-radiative relaxation rates in nanoparticle systems. Applications in the display industry require smaller particle size for both high-resolution and low voltage flat-panel displays. At the same time, they also require rugged and high-efficiency materials. Therefore, the optical and dynamical properties of the nanocrystals will be characterized both alone and after passivation by surface modification or by embedding in a matrix. The approach will be to prepare nanostructured materials, and characterize their structure and morphology by X-ray diffraction, transmission-electron microscopy, atomic-force microscopy, and fluorescence spectroscopy at Virginia Tech. Well-characterized nanostructured materials will then be studied at the University of Georgia using high-resolution spectroscopic techniques to determine how fundamental properties such as oscillator strength, optical dephasing, non-radiative relaxation, phonon dynamics, and energy-transfer processes depend on particle size or surface modification. The collaboration between Virginia Tech and the University of Georgia brings together expertise in nanocrystalline synthesis, processing, and characterization, with expertise in high resolution and nonlinear spectroscopic techniques. The close collaboration between synthesis and spectroscopy groups will allow the PIs to systematically grow and characterize new materials, with property measurements providing rapid feedback to guide material preparation and processing. The synergism of this collaboration will allow much more progress in preparing and understanding very complex nanostructures than if the groups were working alone %%% Novel lanthanide-doped metal-oxide nanostructured materials have potential applications as materials for lasers and optical amplifiers, and as phosphors for flat-panel displays. The results of this research will provide feedback to engineer nanostructures to improve the properties of these materials. The interdisciplinary nature of the collaboration between Virginia Tech and the University of Georgia will provide an excellent educational experience to train future scientists for the multidisciplinary teamwork that is increasingly characteristic of scientific research and technological development. This project is funded as part of Nanotechnology Initiative by the Ceramics and the Solid State Chemistry programs in the Division of Materials Research, the Physical Foundations and Enabling Technologies program in the Division of Electrical and Communication Systems, and the Office of Multidisciplinary Activities in the Mathematical and Physical Sciences Directorate. In addition, the Division of International Programs has provided funding for travel in order for the PIs to perform collaborative research with their counterparts in Russia.