RUI: Using graph theory measures to probe oxygen vacancy and proton conduction in perovskites and double perovskites

非技术总结材料研究部和化学部为该奖项提供资金，该奖项支持燃料电池和太阳能电池所用材料导电性能的理论研究和教育。化石燃料供应的限制、环境考虑以及燃烧燃料发电的相对低效，促使人们在开发替代能源方面做出了相当大的努力。由于能量传递步骤的数量，燃烧的效率本来就很低。燃料电池通过将化学能直接转化为电能，避免了整个燃烧过程，显著提高了效率。太阳能电池直接将光能转化为电能，虽然效率不如燃料电池，但它们利用的是一种可再生资源。这两个过程都比燃烧排放的污染物要少得多，并减少了对石油产品的依赖。固体氧化物燃料电池由夹在离子导体(电解液)中的两个电子传导表面(电极)组成。发电量在很大程度上取决于离子在电解液中移动的速度。在太阳能电池中，电能的生产受到材料中氧原子缺失的限制，氧原子构成了可移动的原子-晶格缺陷。总体而言，了解离子或离子缺陷在材料中的运动对于优化这些器件的性能非常重要。这个项目将阐明离子或空位附近结构的变化如何影响传导途径。对特定材料的模拟以及在本项目中开发的模拟方法将有助于加深我们对传导的知识和理解，并帮助设计出更高效的导体，用于燃料电池和太阳能电池。该项目将包括在芒特霍利奥克学院对本科生进行计算化学、编程和相关数学方面的培训。这些本科生将参加由水星联盟为从事计算化学研究的本科生举办的年度水星会议，该联盟是该联盟的创始成员之一。将开发针对高中生的PI的化学冒险护照扩展计划，并将其发送到参与该计划的11个马萨诸塞州西部图书馆。技术总结材料研究部和化学部为该奖项提供资金，支持钙钛矿和双钙钛矿中氧空位和质子传导的计算研究和教育。带电缺陷导电对许多器件的功能是必不可少的。例如，质子和氧空位有时是燃料电池膜的主要导体；氧空位传输对于燃料电池阴极处的氧还原是必不可少的。此外，太阳能电池中的带隙有时会受到氧空位浓度的调节。该项目将进一步进行计算研究，以了解钙钛矿和双钙钛矿材料中带电-缺陷导电路径如何随着缺陷附近的晶格重组以及导电过程中电荷-缺陷相关性的变化而变化。该项目将扩展PI的缺陷传导路径查找方法和基于时间的中心性度量的用途。中心性度量将不仅用于预测陷阱、关键结点和路径，还将用于预测相关运动，包括质子/质子关联和质子/氧空位关联。补充技术，如经验势上的加速动力学技术，将被用来确定基于图论的方法的效果如何。这个项目将包括在芒特霍利奥克学院对本科生进行计算化学、编程和相关数学方面的培训。这些本科生将参加由水星联盟为从事计算化学研究的本科生举办的年度水星会议，该联盟是该联盟的创始成员之一。将开发针对高中生的PI的化学冒险护照扩展计划，并将其发送到参与该计划的11个马萨诸塞州西部图书馆。

NONTECHNICAL SUMMARYThe Division of Materials Research and the Chemistry Division contribute funds to this award, which supports theoretical research and education on the conduction properties of materials used in fuel- and solar cells. Limitations in the supply of fossil fuels, environmental considerations, and the relative inefficiency of burning fuel to produce electricity have sparked considerable efforts in developing alternative sources of energy. Combustion is inherently inefficient due to the number of energy transfer steps. Fuel cells avoid the entire combustion process by directly converting chemical energy into electricity, significantly increasing efficiency. Solar cells directly convert light energy into electrical energy and, while not as efficient as fuel cells, they make use of a renewable resource. Both processes emit significantly fewer pollutants than combustion and reduce dependence on petroleum products. A solid oxide fuel cell is comprised of two electron-conductive surfaces (electrodes) sandwiching a conductor (electrolyte) of ions. Electricity production is substantially determined by how fast the ions move through the electrolyte. In solar cells, electricity production is limited by missing oxygen atoms in the material, which comprise mobile atom-lattice defects. Overall, understanding ion or ion-defect motion through a material is important for optimizing the performance of these devices. This project will clarify how changes in structure near an ion or vacancy influence conduction pathways. Simulations of specific materials as well as the simulation methods developed in this project will be useful in furthering our knowledge and understanding of conduction, and help engineer more efficient conductors for use in fuel- and solar cells. This project will include training undergraduate women at Mount Holyoke College in computational chemistry, programming, and the associated mathematics. These undergraduates will attend the annual MERCURY conference organized for undergraduates doing research in computational chemistry by the MERCURY consortium, of which the PI is one of the founding members. An extension to the PI's Passport to Chemistry Adventure outreach program targeting high-school students will be developed and sent to the eleven western Massachusetts libraries participating in the program. TECHNICAL SUMMARYThe Division of Materials Research and the Chemistry Division contribute funds to this award, which supports computational research and education on oxygen-vacancy and proton conduction in perovskites and double perovskites. Charged-defect conduction is essential to the functioning of many devices. For example, protons and oxygen vacancies are sometimes the main conductors in fuel-cell membranes; oxygen-vacancy transport is essential for oxygen reduction at the cathode of a fuel cell. Furthermore, band gaps in solar cells are sometimes tuned by oxygen-vacancy concentration. The project will further computational investigations to understand how charged-defect conduction paths in perovskite and double-perovskite materials change with lattice restructuring near the defect, as well as with charge-defect correlation during the conduction process. The project will extend the uses of the PI's defect conduction path finding methods and centrality measures based on time. Centrality measures will be used to not only predict traps, key nexuses, and pathways, but to also predict correlated motion including proton/proton correlation and proton/oxygen-vacancy correlation in acceptor-doped barium zirconate. Complementary techniques such as accelerated dynamics techniques on an empirical potential will be used to determine how well graph-theory-based methods work.This project will include training undergraduate women at Mount Holyoke College in computational chemistry, programming, and the associated mathematics. These undergraduates will attend the annual MERCURY conference organized for undergraduates doing research in computational chemistry by the MERCURY consortium, of which the PI is one of the founding members. An extension to the PI's Passport to Chemistry Adventure outreach program targeting high-school students will be developed and sent to the eleven western Massachusetts libraries participating in the program.