GOALI: Investigating the Defect Structures in Superconducting Materials for Power and Electronic Applications

80年代中期发现的高tc超导性为新型、高效、强大、敏感的电子设备和输电线路带来了希望。然而，与这些钙钛矿陶瓷相关的材料问题的复杂性迄今为止严重限制了该技术的实现。在涉及超导体的所有应用中，晶界和其他结构缺陷的特性尤为重要。在这个程序中，目的是在最先进的透射电子显微镜中使用先进的结构和电子表征方法，首先了解然后潜在地去除这些缺陷的有害特性。这项工作涉及与美国超导技术的领导者美国超导公司的强有力合作，并包括对研究生进行最先进的表征方法及其在工业研究和开发中的应用的重要培训。该计划的另一个好处是建立一个远程访问合作实验室，允许美国任何人在非现场使用显微镜方法进行研究，特别是通过加州大学戴维斯分校建立的环境，农业和技术纳米材料（NEAT）计划管理的外展项目。技术描述：在这个项目中，提出在扫描透射电子显微镜（STEM）中使用原子分辨率z对比成像和电子能量损失谱（EELS）的组合来研究几种高tc系统中晶界处的结构-性能关系。这些相关技术先前已被证明可以提供结构、组成和局部载流子浓度（与转变温度Tc和临界电流Jc有关）之间联系的准确信息。目前的研究计划将通过利用独特的实验设备（像差校正显微镜，单色显微镜和原位级）在升高和降低温度（即低于Tc）和环境环境中进行原子尺度测量，使实验进一步迈出重要的一步。这些实验将允许温度（加工）历史对超导状态下边界特性的影响。该项目旨在研究三种处于不同商业发展阶段的材料；主要是YBaCuO涂层导体，以及BiSrCaCuO线和MgB2。每种系统都有自己的实验挑战，从确定晶界的载流子相互作用到了解热处理过程中超导相的形成。将这些研究与美国超导公司的相关项目相结合，将对超导现象有一个完整的了解，并使这些发展迅速融入新的材料加工路线。

NON-TECHNICAL DESCRIPTIONThe discovery of high-Tc superconductivity in the mid-80s held the promise of new, efficient, powerful, and sensitive electronic devices and power transmission wires. However, the sheer complexity of the materials issues related to these perovskite ceramics has so far severely limited the realization of this technology. Of particular importance for all applications involving superconductors are the properties of grain boundaries and other structural defects. In this program, the aim is to use advanced methods of structural and electronic characterization in state-of-the-art transmission electron microscopes to first understand and then potentially remove the deleterious properties of these defects. This work involves a strong collaboration with the US leader in superconductor technology, American Superconductor, and includes significant training of graduate students in both the most advanced characterization methods and their application to industrial research and development. An additional benefit of this program will be the establishment of a remote access collaboratory, allowing the microscope methods to be used off-site for research by anyone in the US and in particular, for outreach programs administered through the established Nanomaterials for the Environment, Agriculture and Technology (NEAT) initiative at UC-Davis.TECHNICAL DESCRIPTIONIn this program, it is proposed to investigate the structure-property relationships at grain boundaries in several high-Tc systems using a combination of atomic resolution Z-contrast imaging and electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM). These correlated techniques have been shown previously to provide accurate information on the link between structure, composition, and the local carrier concentration (which is related to the transition temperature, Tc, and the critical current, Jc). The current research program will take the experiments an important step further by utilizing unique experimental facilities (aberration corrected microscopes, monochromated microscopes and in-situ stages) to perform the atomic scale measurements both at elevated and lowered temperatures (i.e. below Tc) and in an ambient environment. These experiments will allow the effect of temperature (processing) history on the boundary properties to be characterized in the superconducting state. The program aims to work on three classes of materials at various stages of commercial development; primarily YBaCuO coated conductors, and also BiSrCaCuO wires and MgB2. Each of these systems presents their own experimental challenge, that range from determining the carrier interactions at grain boundaries to understanding the formation of the superconducting phases during heat treatments. Combining these studies into a correlated program with American Superconductor will develop a complete understanding of superconducting phenomena and allow these developments to be rapidly incorporated into new materials processing routes.