Determination of Atomic Scale Structure Property Relationships in High-Temperature Superconductors for Power Transmission Applications

9803021布朗宁这个项目将研究结构/性能关系，以确定将高TC超导体纳入可行器件的最佳微结构。这些材料的电子传导对在氧化物材料加工过程中引入的原子级缺陷极其敏感。在扫描电子显微镜(STEM)中，可以通过原子分辨率Z衬度成像和电子能量损失谱来确定原子尺度缺陷与电子电导之间的关系。这些技术可以在STEM中同时进行，图像用于确定原子结构，光谱用于确定电子结构。光谱的特征可以与电荷载流子浓度相关联，从而允许在低于相干长度的尺度上量化弱连接。原子分辨率分析技术将应用于目前正在开发的两个系统，用于电力传输和高磁场应用。在与美国超导公司的合作下，该提案的主要目的是调查Bi2Sr2Ca2Cu308(2223)带材中缺陷的特性，并将它们与加工条件联系起来。在已建立的成功合作计划的基础上，该项目将调查带材内缺陷的分布，以及2223相的形成与带材微观结构之间的关系。该方案的第二个目标是研究在织构金属衬底上制备的YBa2Cu307薄膜的性质。虽然这是一种可行的产品，但这种最近开发的制造程序提供了2223磁带的可能替代方案。研究将侧重于将性能与单个晶界和单晶的结果进行比较，目的是确定这种材料的大规模制造路线。自从在陶瓷氧化物中发现高温超导电性以来，这些材料有望成为高效、强大和灵敏的电子器件和输电线。这项研究的结果将有助于确定生产适合商业应用的改进磁带的加工路线。这项研究将对高温超导体的应用产生重大影响。***

9803021 Browning This project will study the structure/property relationships in order to determine the optimum microstructure for the incorporation of high-TC superconductors into viable devices. The electronic conduction of these materials is extremely sensitive to atomic-scale defects that are introduced during the processing of the oxide material. The relationship between the atomic-scale defects and the electronic conduction can be determined by atomic resolution Z-contrast imaging and electron energy loss spectroscopy in the scanning transmission electron microscope (STEM). These techniques can be performed simultaneously in the STEM, with the image being used to determine the atomic structure and the spectrum being used to determine the electronic structure. Features of the spectrum can be correlated with the charge carrier concentration, allowing weak-links to be quantified on a scale below the coherence length. The atomic resolution analysis techniques will be applied to two systems that are currently being developed for power transmission and high-magnetic field applications. In collaboration with American Superconductor Corporation, a major thrust of the proposal is to investigate the properties of defects in Bi2Sr2Ca2Cu308 (2223) tapes and relate them to processing conditions. Building on an established successful collaborative program, this project will investigate the distribution of defects within the tapes and the relationship between the formation of the 2223 phase and the tape microstructure. The second goal of this proposal is to investigate the properties of YBa2Cu307 films produced on textured metal substrates. Although further from a viable product, this recently developed fabrication procedure offers a possible alternative to the 2223 tapes. Research will focus on a comparison of properties with the results from individual grain boundaries and single crystals, with the aim of determining the route to large-scale fabrication of t hese materials. %%% Since the discovery of high-TC superconductivity in the ceramic oxides, these materials have held the promise of efficient, powerful and sensitive electronic devices and power transmission wires. The results of this research will help determine the processing route to produce improved tapes suitable for commercial applications. The research will have a significant impact on the applications of high-TC superconductors. ***