Oxide Ion Conduction Mechanisms in Bismuth Perovskites

非技术描述：在能源系统的广泛领域中的新兴应用需要具有高离子电导率、化学和热稳定性并且由环境友好且廉价的材料组成的新材料。该项目的重点是发展含铋陶瓷的氧电导率和控制氧的流动性的局部原子结构之间的关系的理解。这项研究将涉及一些陶瓷化合物的合成，其离子电导率的测量，并利用中子和X射线散射表征其局部结构。随着这些发现指导的性能的改进，可以考虑许多与能源相关的应用，例如中温固体氧化物燃料电池，其具有作为具有成本效益的清洁电源的巨大潜力。在这个为期四年的项目中，研究为新能源材料的开发增加了宝贵的专业知识，并形成了两篇博士论文的基础，一篇是化学，另一篇是材料科学。此外，该项目还包括一个高影响力的K-12外展活动，将两名高中生作为现有计划的一部分，在俄勒冈州州立大学（OSU）的青年科学与工程暑期体验（SESEY）。 该项目还通过一个名为“市场透镜”（LoM）的专业发展计划探索商业化活动，该计划在俄勒冈州立大学通过研究生教育创新（IGE）的国家科学基金会研究培训（NRT）奖获得支持。该项目建立在铋钙钛矿材料的缺陷化学和结构分析的最新进展基础上，旨在发展基本的理解在两个铋钙钛矿系统，钛酸铋钠（NBT）和钛酸钡-钛酸铋锌（BT-BZT）的主导离子导电机制。这两种材料系统最近都显示出在低于600摄氏度的温度下表现出与氧化钇稳定的氧化锆相当的离子电导率值。 该项目的首要目标是确定铋钙钛矿中独特的局部结构扭曲，使这些材料具有高的氧电导率。具体的研究活动包括以下目标：（i）系统地合成和处理NBT和BT-BZT基陶瓷以控制氧化学计量的水平，（ii）表征NBT和BT-BZT基材料的电子性质，重点是离子电导率，和（iii）表征局部结构、平均结构、以及NBT和BT-BZT基材料的氧非化学计量比，重点是掺杂和加工条件如何影响这种行为。对氧化物离子传导机制的更深入了解将有助于指导新兴能源应用新材料的开发。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL DESCRIPTION: Emerging applications in the broad area of energy systems require new materials that have high ionic conductivities, chemical and thermal stability, and are composed of environmentally benign and inexpensive materials. This project is focused on developing an understanding of the relationship between the oxygen conductivity of bismuth-containing ceramics and the local atomic structure that controls the mobility of oxygen. This research will involve the synthesis of a number of ceramic compounds, measurement of their ionic conductivity, and characterization of their local structure using neutrons and X-ray scattering. With improvements in the properties guided by these findings, there are many energy-related applications that can be considered such as intermediate temperature solid oxide fuel cells, which have great potential as a cost-effective, clean power source. The research in this four-year project adds valuable expertise in the development of new energy materials and forms the basis of two doctoral theses, one in chemistry and the other in materials science. In addition, the project incorporates a high-impact K-12 outreach activity by hosting two high school students into the laboratory as part of an existing program, the Summer Experience in Science and Engineering for Youth (SESEY) at Oregon State University (OSU). This project also explores commercialization activities through a professional development program called Lens of the Market (LoM) which is supported at OSU through an National Science Foundation Research Traineeship (NRT) award in Innovations in Graduate Education (IGE).TECHNICAL DETAILS: This project builds upon recent developments on the defect chemistry and structural analysis of bismuth perovskite materials with an aim to develop a fundamental understanding of the dominant ionic conduction mechanisms in two bismuth perovskite systems, sodium bismuth titanate (NBT) and barium titanate-bismuth zinc titanate (BT-BZT). Both of these material systems have recently been shown to exhibit ionic conductivity values comparable to yttria-stabilized zirconia at temperatures below 600 degrees C. The overarching objective of this project is to identify the unique local structural distortions in bismuth perovskites that enable high oxygen conductivities in these materials. The specific research activities include the following objectives: (i) to systematically synthesize and process NBT and BT-BZT-based ceramics to control the level of oxygen stoichiometry, (ii) to characterize the electronic properties of NBT and BT-BZT-based materials, with a focus on the ionic conductivity, and (iii) to characterize the local structure, average structure, and oxygen non-stoichiometry of NBT and BT-BZT-based materials, with the focus on how doping and processing conditions influence this behavior. A greater understanding of the oxide ion conduction mechanisms will help guide the development of new materials for emerging energy applications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.