Local Atomic Structure of Nearly-periodic Solids

近周期固体的局域原子结构

• 批准号: 9628134
• 负责人: Takeshi Egami
• 金额: $ 52.44万
• 依托单位: University of Pennsylvania
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-07-01 至 2001-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9628134&HistoricalAwards=false
• 关键词: Local; Atomic; Structure; Nearly; periodic

9628134 Egami The local atomic structure of some technologically important new materials, mostly crystalline oxides, will be determined by non-crystallographic diffraction techniques including the atomic pair-distribution analysis. The materials studied include superconducting cuprates, manganates with colossal magnetoresistance, CeO2/ZrO2 mixture for automotive catalyst support, and metallic glasses. Many of these materials have a periodic crystalline structure in average, but show significant local structural deviations from perfect periodicity that can be critically important in determining their properties. Experiments will be carried out using pulsed neutrons and synchrotron x-rays available at national facilities. Results will be analyzed by computer modeling methods developed in our group. To facilitate understanding of the results, theoretical studies will be carried out in collaboration with other theory groups. %%% The properties of a material ultimately depend on the atomic structure. Recent research has shown that the local atomic structure, that is, the structure within a few atomic diameters of an atom, may not be the average structure of the material. In many cases, such local variations do not have significant consequences, but in many cases the properties of a material are critically dependent on the local structure rather than the average structure. The purpose of this project is to determine the local atomic structure of these materials using non-crystallographic scattering techniques. Three materials systems will be examined, all of which are of technological importance. ***

9628134 Egami某些具有技术重要的新材料（主要是晶体氧化物）的局部原子结构将由非晶格衍射技术（包括原子配对分布分析）确定。所研究的材料包括超导粉提土，具有巨大磁性的锰，CEO2/ZRO2混合物用于汽车催化剂支撑和金属玻璃。这些材料中的许多平均具有周期性的结构结构，但显示出明显的局部结构偏离与完美周期性的偏差，这对于确定其性质至关重要。实验将使用国家设施可用的脉冲中子和同步X射线进行。 结果将通过我们小组中开发的计算机建模方法进行分析。为了促进对结果的理解，理论研究将与其他理论组合作进行。 %%;材料的特性最终取决于原子结构。 最近的研究表明，局部原子结构，即原子的少数原子直径内的结构，可能不是材料的平均结构。 在许多情况下，这种局部变化并没有重大后果，但是在许多情况下，材料的性质严重取决于局部结构，而不是平均结构。该项目的目的是使用非结晶散射技术确定这些材料的局部原子结构。 将检查三种材料系统，所有这些都具有技术重要性。 ***