Crystal Size Effects on the Lattice Parameter of Nano-scaled Oxides

晶体尺寸对纳米氧化物晶格参数的影响

• 批准号: 1206764
• 负责人: Siu-Wai Chan
• 金额: $ 44万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-01 至 2017-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1206764&HistoricalAwards=false
• 关键词: Crystal; Size; Effects; Lattice; Parameter

NON-TECHNICAL DESCRIPTION: Prof. Siu-Wai Chan is examining how nanosized crystals expand or contract at the atomic level, and how they are affected by crystal size, temperature, pressure, and the presence of structural irregularities. The intellectual value of her research lies in understanding how small structural changes make profound changes in material behavior. This enhanced understanding will help in the development of new materials with improved properties. A better understanding of bonding should contribute to the development of nanoparticle synthesis methods with greater control over critical properties. Insight into the structure and defects in metal oxide nanoparticles may provide a knowledge base for the rational design of more efficient and less costly catalysts for cleaner air and sustainable energy. Undergraduate, master's, and doctoral students are being trained in conducting research, and new demonstration units (that incorporate the results of this study) are being developed for a New York City high school visitation program.TECHNICAL DESCRIPTION: Prof. Siu-Wai Chan is examining changes in the lattice parameter of metal oxides with crystallite-size, defect formation, temperature, and pressure. She employs both traditional and synchrotron-based, time-resolved X-ray diffraction. The coefficient of thermal expansion is calculated through measurements of the lattice in response to temperature variations. Similarly, measuring how the lattice responds to pressure allows for a calculation of the bulk modulus. She is interested in determining if these quantities are dependent on particle size in the nanoscale regime. The intellectual value of her research lies in the fact that small structural changes often generate profound changes in properties. Therefore, this project will provide a window to view the nature of bonding in nanoparticles and will enable a better understanding of surface stress and surface energy to be gained. It will also help to determine if the macroscopic based theory of surface stress, which has successfully predicted the lattice contraction in noble metal crystallites, can be used for ionic solids. The opportunity to tackle these issues is timely because mono-dispersed nanoparticles are now widely available.

非技术描述：陈兆伟教授正在研究纳米晶体如何在原子水平上膨胀或收缩，以及它们如何受到晶体大小，温度，压力和结构不规则性的影响。 她的研究的知识价值在于理解小的结构变化如何使物质行为发生深刻变化。 这种增强的理解将有助于开发具有改进性能的新材料。 更好地理解键合应有助于纳米粒子合成方法的发展，更好地控制关键性能。 深入了解金属氧化物纳米颗粒的结构和缺陷，可以为合理设计更高效、成本更低的催化剂提供知识基础，以实现更清洁的空气和可持续能源。 本科生、硕士生和博士生正在接受进行研究的培训，并且正在为纽约市高中访问计划开发新的示范单元（包含本研究的结果）。技术说明：陈兆伟教授正在研究金属氧化物的晶格参数随晶粒尺寸、缺陷形成、温度和压力的变化。她采用传统的和基于同步加速器的时间分辨X射线衍射。 热膨胀系数是通过测量晶格对温度变化的响应来计算的。类似地，测量晶格如何响应于压力允许体积模量的计算。 她感兴趣的是确定这些量是否取决于纳米级范围内的颗粒大小。 她的研究的知识价值在于这样一个事实，即小的结构变化往往会产生深刻的性质变化。 因此，该项目将提供一个窗口，以查看纳米粒子中的键合性质，并将使表面应力和表面能得到更好的理解。 这也将有助于确定是否宏观为基础的表面应力理论，它已成功地预测了贵金属微晶的晶格收缩，可用于离子固体。 解决这些问题的机会是及时的，因为单分散纳米颗粒现在已经广泛使用。