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

材料研究部门和化学部门为该奖项提供资金，以支持燃料和太阳能电池中使用的材料的传导特性的理论研究和教育。矿物燃料供应的限制、环境方面的考虑以及燃烧燃料发电的相对低效率，促使人们在开发替代能源方面作出了相当大的努力。由于能量传递步骤的数量，燃烧本身是低效的。燃料电池直接将化学能转化为电能，从而避免了整个燃烧过程，大大提高了效率。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，但它们利用了可再生资源。这两种方法排放的污染物都比燃烧少得多，并减少了对石油产品的依赖。固体氧化物燃料电池由两个电子导电表面（电极）夹在离子导体（电解质）中组成。电能的产生在很大程度上取决于离子通过电解质的速度。在太阳能电池中，由于材料中缺少氧原子（构成可移动的原子晶格缺陷），电力生产受到限制。总的来说，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。该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。特定材料的模拟以及本项目中开发的模拟方法将有助于进一步加深我们对传导的认识和理解，并有助于设计更有效的导体，用于燃料和太阳能电池。该项目将包括对芒特霍利奥克学院的女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组织的年度水星会议，PI是该联盟的创始成员之一。一项针对高中学生的PI“化学冒险护照”扩展计划将被开发并发送给参与该计划的11个马萨诸塞州西部图书馆。技术概述材料研究部和化学部为该奖项提供资金，用于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。电荷缺陷传导对许多器件的功能至关重要。例如，质子和氧空位有时是燃料电池膜中的主要导体；氧空位输运是燃料电池阴极氧还原的关键。此外，太阳能电池中的带隙有时是由氧空位浓度调节的。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的电荷-缺陷传导路径如何随着缺陷附近的晶格重组而变化，以及在传导过程中电荷-缺陷的相关性。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使用。中心性测量不仅用于预测陷阱、关键联系和途径，还用于预测受体掺杂锆酸钡中的相关运动，包括质子/质子相关和质子/氧空位相关。补充技术，如经验势上的加速动力学技术，将用于确定基于图论的方法的工作效果。该项目将包括对芒特霍利奥克学院的女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组织的年度水星会议，PI是该联盟的创始成员之一。一项针对高中学生的PI“化学冒险护照”扩展计划将被开发并发送给参与该计划的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.