Nanocrystal growth and exotic doping at extremely high-pressure hydrothermal conditions

在这个由化学系大分子、超分子和纳米化学项目资助的项目中，加州大学伯克利分校的张恒忠和Jillian Banfield将研究二氧化钛纳米颗粒的生长、结构和形态演变以及在极高压水热条件下杂质的结构掺入。该方法是在存在和不存在掺杂剂的情况下合成二氧化钛纳米颗粒，采用特殊的金刚石对顶砧单元在非常高的温度和压力下在超临界水中进行纳米颗粒生长和结构变化的原位同步加速器X射线衍射研究，对纳米晶体进行非原位显微镜和X射线吸收研究以确定掺杂剂分布，并最终使用理论模拟方法来理解在这种条件下二氧化钛纳米颗粒的物理和化学性质。 更广泛的影响涉及本科生培训和教育纳入研究项目，研究成果纳入本科实验室课程，研究成果通过出版物，演示文稿和纳米地球科学网站的广泛传播，以及这项研究在许多科学领域的潜在影响。纳米晶体是尺寸在1到100之间的小块材料。纳米，比人类头发的宽度小大约10，000倍，它们对包括颜料，电子和医学成像在内的广泛技术都很重要。 控制纳米晶体生长以实现所需规格（如相、尺寸、形态和缺陷结构）的能力是实现其使用纳米技术的关键。在极端温度和压力条件下的纳米晶体生长在很大程度上是未经探索的，该项目将使用最先进的实验技术和理论和计算建模来追求这一研究课题。这些研究将增强我们对操纵纳米晶体的知识，并可能导致发现新的纳米晶体结构和成分。

In this project funded by the Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division, Hengzhong Zhang and Jillian Banfield of the University of California at Berkeley will investigate titania nanocrystal growth, structure and morphology evolution, and structural incorporation of impurities under extremely high pressure hydrothermal conditions. The approach is to synthesize titania nanoparticles with and without the presence of dopants, to employ a special diamond anvil cell in performing an in situ synchrotron X-ray diffraction study of nanocrystal growth and structure change in supercritical water at very high temperatures and pressures, to perform ex situ microscopy and X-ray absorption studies on the nanocrystals to determine dopant distributions, and finally to use theoretical modeling methods to understand the physical and chemical properties of titania nanoparticles under such conditions. The broader impacts involve the integration of undergraduate student training and education into the research project, the incorporation of research results into the undergraduate laboratory curriculum, the broad dissemination of research results through publications, presentations and a nanogeoscience website, and the potential impacts of the research in many areas of science.Nanocrystals are small pieces of material with dimensions on the order of 1 to 100 nanometers, which is about 10,000 times smaller than the width of a human hair, and they are important for a wide range of technologies including pigments, electronics, and medical imaging. The ability to control nanocrystal growth to achieve required specifications such as phase, size, and morphology and defect structure is key to the realization of their use nanotechnologies. Nanocrystal growth under extreme temperature and pressure conditions is largely unexplored, and this project will pursue this research topic using both state-of-the-art experimental techniques and theoretical and computational modeling. Such research will enhance our knowledge about manipulating nanocrystals and potentially lead to the discovery of new nanocrystal structures and compositions.