Local Atomic Structure and Properties of Transition Metal Oxides using Pair Distribution Function Analysis

使用对分布函数分析过渡金属氧化物的局域原子结构和性质

• 批准号: 9700966
• 负责人: Simon Billinge
• 金额: $ 27万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-01 至 2000-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9700966&HistoricalAwards=false
• 关键词: Local; Atomic; Structure; Properties; Transition

9700966 Billinge The local structure of transition metal oxides (TMOs) exhibiting interesting electronic properties will be studied using the pair- distribution function (PDF) analysis of powder diffraction data. This technique utilizes Bragg and diffuse scattering over a very wide range of momentum transfer (Q) and yields the atomic short-range order directly. It goes beyond the approximation of perfect crystallinity and allows the local structure to be solved on length-scales from 1-20 angstroms. This type of structural analysis will be applied to a variety of transition metal oxides such as high-Tc materials, layered manganites and nickelates and the colossal magnetoresistant manganites. In these materials, the structure can respond to the electronic state and we will look for correlations between changes in electrical properties and local structural effects. In this way, the nature of localized electronic states, such as polaronic, bipolaronic and charge-phase-separated states, will be elucidated. %%% The great materials scientist F.C. Franck is reported to have said "crystals are like people -- it is the defects which make them interesting". Indeed, many of the most interesting, and useful, new materials exhibit a high degree of atomic disorder; and it is often the defects which give them their interesting properties. This presents special challenges for solid state physicists and materials scientists because of the difficulty of studying atomic level defects in materials. We will be using the technique of atomic pair- distribution function (PDF) analysis of neutron and x-ray diffraction to characterize transition metal oxides; an important group of materials which fall into the above category. We will use novel data analysis and modeling techniques, developed both by us and by others, to extract quantitative structural information from the data and correlate these observations with the measured electrical properties. A number of these material s show great technological promise, such as the high-Tc superconductors and colossal magnetoresistant manganite materials which may have an application in computer read/write heads for example. We are attempting to understand the role that atomic defects play in their interesting electrical properties. ***

9700966 Billinge 将使用粉末衍射数据的配对分布函数 (PDF) 分析来研究具有有趣电子特性的过渡金属氧化物 (TMO) 的局部结构。 该技术在非常宽的动量传递 (Q) 范围内利用布拉格和漫散射，并直接产生原子短程有序。 它超越了完美结晶度的近似值，并允许在 1-20 埃的长度尺度上求解局部结构。这种类型的结构分析将应用于各种过渡金属氧化物，例如高 Tc 材料、层状锰酸盐和镍酸盐以及巨磁阻锰酸盐。 在这些材料中，结构可以响应电子态，我们将寻找电性能变化与局部结构效应之间的相关性。 通过这种方式，将阐明局域电子态的性质，例如极化态、双极化态和电荷相分离态。 %%% 伟大的材料科学家 F.C.据报道，弗兰克曾说过“晶体就像人一样——正是缺陷使它们变得有趣”。 事实上，许多最有趣、最有用的新材料都表现出高度的原子无序性。正是这些缺陷赋予了它们有趣的特性。 由于研究材料中的原子级缺陷非常困难，这给固态物理学家和材料科学家带来了特殊的挑战。 我们将使用中子原子对分布函数 (PDF) 分析和 X 射线衍射技术来表征过渡金属氧化物；属于上述类别的一组重要材料。 我们将使用我们和其他人开发的新颖的数据分析和建模技术，从数据中提取定量结构信息，并将这些观察结果与测量的电特性相关联。 其中许多材料显示出巨大的技术前景，例如高温超导体和巨大的磁阻锰酸盐材料，它们可能在计算机读/写头中得到应用。 我们正在尝试了解原子缺陷在其有趣的电特性中所扮演的角色。 ***