SusChEM: Defect Mechanisms in Bismuth Perovskites

SusChEM：铋钙钛矿的缺陷机制

• 批准号: 1308032
• 负责人: David Cann
• 金额: $ 40万
• 依托单位: Oregon State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1308032&HistoricalAwards=false
• 关键词: SusChEM; Defect; Mechanisms; Bismuth; Perovskites

NON-TECHNICAL DESCRIPTION:Research on bismuth-containing perovskite materials has grown steadily over the last decade due in part to energy efficiency considerations and environmental standards such as the Reduction of Hazardous Substances (RoHS) directive. These same regulations were the motivation for the development of Pb-free solders that were broadly implemented across the electronics industry. While interest in bismuth perovskites as a potential materials replacement for Pb-based electronic materials has grown in recent years, there have been few studies on the role of point defects (e.g. cation and anion vacancies) in these materials. This project contributes to the fundamental understanding of the role of defects in bismuth perovskites to help guide the development of these sustainable materials for emerging applications. This research is critical because point defects ultimately have a profound influence on phenomena (such as piezoelectric fatigue, aging, reliability, and high temperature resistivity). Fatigue behavior can be a limiting factor in high performance microelectromechanical systems (MEMS) devices, such as ink jet printers, accelerometers, and actuators. This work also impacts the development of capacitor materials for high temperature and high electric field applications because robust electrical properties are important for devices for down hole drilling electronics for geothermal systems, high temperature SiC-based passive components, and others.TECHNICAL DETAILS:This project combines synthesis, analysis and computational approaches to investigate the dominant defect species and relevant defect equilibrium conditions for bismuth-containing perovskites to help guide the development of these materials for emerging applications. Point defects are prevalent in these systems given that many Bi-based perovskites feature tetravalent Ti on the B-site which has been shown to exhibit oxygen non-stoichiometry at high temperatures from a reduction reaction. Furthermore, the common A-site cations of Bi3+, Na+ and K+ are all known to be volatile under the typical processing conditions of both ceramics and thin films. This project involves three experimental tasks including synthesis of ceramics with controlled cation and anion non-stoichiometry, characterization techniques to identify the nature and concentration of the defect species, and establishing the linkage between the defect chemistry and the materials properties through measurements of the dielectric and piezoelectric properties and electrical resistivity. Finally, computational (first principles) efforts are integrated throughout this project to complement and verify the experimental results and to help guide future experiments. In addition to training and mentoring undergraduate and graduate students in materials research, this project incorporates a high-impact K-12 outreach activity by hosting two high school students into the laboratory at OSU each summer as part of the Summer Experience in Science and Engineering for Youth (SESEY).

非技术描述：在过去十年中，含铋钙钛矿材料的研究稳步增长，部分原因是出于能源效率考虑和环境标准，如减少有害物质（RoHS）指令。 这些相同的法规也是开发无铅焊料的动力，并在电子行业中广泛实施。 虽然近年来人们对铋钙钛矿作为铅基电子材料的潜在材料替代品的兴趣有所增长，但对这些材料中点缺陷（例如阳离子和阴离子空位）的作用的研究很少。 该项目有助于从根本上理解铋钙钛矿中缺陷的作用，以帮助指导这些可持续材料的开发。 这项研究是至关重要的，因为点缺陷最终会对现象（如压电疲劳，老化，可靠性和高温电阻率）产生深远的影响。 疲劳行为可能是高性能微机电系统（MEMS）装置（例如喷墨打印机、加速度计和致动器）中的限制因素。这项工作还影响了高温和高电场应用电容器材料的开发，因为稳健的电气性能对于地热系统井下钻井电子设备、高温SiC基无源元件等非常重要。技术参数：这个项目结合了综合，分析和计算方法，以调查占主导地位的缺陷物种和相关的缺陷平衡条件，铋，含有钙钛矿的材料，以帮助指导这些材料的开发，用于新兴应用。 点缺陷在这些体系中普遍存在，因为许多基于Bi的钙钛矿在B位点上具有四价Ti，这已经显示出在高温下从还原反应表现出氧的非化学计量。 此外，已知常见的A位阳离子Bi 3+、Na+和K+在陶瓷和薄膜的典型加工条件下都是挥发性的。该项目涉及三个实验任务，包括合成陶瓷与控制阳离子和阴离子非化学计量，表征技术，以确定的性质和浓度的缺陷物种，并建立之间的联系，通过测量的介电和压电性能和电阻率的缺陷化学和材料性能。 最后，计算（第一原理）的努力是整个项目的整合，以补充和验证实验结果，并帮助指导未来的实验。 除了培训和指导材料研究的本科生和研究生外，该项目还包括一个高影响力的K-12外展活动，每年夏天在俄勒冈州立大学的实验室举办两名高中生，作为青年科学与工程暑期体验（SESEY）的一部分。