NSF-Europe: Nano-Structured Ionic Materials: Impact on Properties and Performance

在这个项目中，我们全面研究了晶粒边界对纳米级离子材料的离子和电子输运特性的影响，其中空间电荷效应甚至在晶粒核心内也可能主导输运。薄膜加工方法将用于生产萤石（如二氧化铈）和钙钛矿（如LSM）基薄膜，这些薄膜具有可控的微观结构，从而产生柱状或等轴的晶粒结构，晶粒尺寸从纳米到微米不等。扩散技术将进一步允许在选定的边界上掺杂各种具有不同离子半径和电荷的元素。样品的结构和化学分析将通过扫描电镜和透射电镜进行。HRTEM将用于获得晶界结构的详细信息。光刻方法将用于制造微电极，使其能够将注意力集中在一个或少数边界上，并通过电学和电化学手段以高度系统的方式检查三相边界的作用。将研制仪器，使这些研究能够在现场进行，作为温度和大气的功能。描述晶界结构、化学和晶粒尺寸对缺陷平衡和输运的综合作用的模型将根据本研究中进行的测量进行改进和检查。离子和混合离子-电子导体（MIEC）是与能量转换和环境监测相关的战略应用，包括电池，燃料电池，渗透膜和传感器。例如，燃料电池具有高能量转换效率和低排放，有望取代各种规模的燃烧发电机。在燃料电池中使用纳米结构的离子材料可能有助于降低温度，从而提供更快的启动时间、更好的稳定性、更低的成本和更简单的热管理。由纳米尺寸的薄膜制成的微型燃料电池，进一步保证了便携式电子设备（如笔记本电脑）的扩展操作。本研究将研究扩展到纳米尺度对燃料电池运行优化的材料性能的影响，以及如何利用这些差异来改善这些和相关设备的性能。本项目由美国国家科学基金会多学科活动办公室、材料研究部（陶瓷）和国际办公室（西欧）共同资助，作为美国国家科学基金会与欧洲材料研究合作项目（NSF 02-135）。该项目正在与德国卡尔斯鲁厄的卡尔斯鲁厄大学和德国斯图加特的马克斯普朗克固体研究所合作进行。

In this project, we undertake a comprehensive study of the effects of grain boundaries on the ionic and electronic transport properties of nanoscale ionic materials in which space charge effects may dominate transport even within the core of the grains. Thin-film processing methods will be used to generate fluorite (e.g. ceria) and perovskite (e.g. LSM)-based films with controlled microstructures resulting in columnar or equi-axed grain structures with grains sizes ranging from the nano- to the micro-scale. In-diffusion techniques will further allow selected boundaries to be doped with a variety of elements with differing ionic radii and charge. Structural and chemical analysis of the specimens will be carried out by SEM and TEM. HRTEM will be used to obtain detailed information about the structure of grain boundaries. Photolithographic methods will be used to fabricate microelectrodes with ability to focus attention on one or a small number of boundaries and to examine the role of triple phase boundaries in a highly systematic manner by both electrical and electrochemical means. Instrumentation will be developed to enable such studies to be performed in situ as functions of temperature and atmosphere. Models describing the combined roles of grain boundary structure and chemistry and grain size on defect equilibria and transport will be refined and examined in relation to the measurements performed in this study.Ionic and mixed ionic-electronic conductors (MIEC) are of interest for strategic applications related to energy conversion and environmental monitoring including batteries, fuel cells, permeation membranes and sensors. Fuel cells, for example, with high-energy conversion efficiencies and low emissions show promise as a replacement for combustion-based electrical generators of all sizes. Using nanostructured ionic materials within fuel cells could potentially facilitate lower temperature operation and thereby provide faster start-up times, improved stability, reduced cost and less complicated thermal management. Micro-fuel-cells, fabricated from thin films with nanodimensions, further promise extended operation of portable electronic devices such as laptop computers. This study will examine how the properties of materials optimized for fuel cell operation are influenced by extension to the nanoscale and how these differences can be utilized in improving the performance of these and related devices.This NSF project is co-funded by the Office of Multidisciplinary Activities, and the Division of Materials Research (Ceramics) and the International Office (Western Europe) as a Cooperative Activity in Materials Research between the NSF and Europe (NSF 02-135). This project is being carried out in collaboration with the University of Karlsruhe, Karlsruhe, Germany and the Max Planck Institute for Solid State Research, Stuttgart, Germany.