Understanding Oxygen Exchange and Transport at Surfaces and Grain Boundaries of Electroceramics

非技术描述：许多重要技术依赖于利用和操纵氧气的能力。例如，大部分能量来自氧气通过燃烧过程与燃料反应。环境技术，如汽车催化转化器，通过与氧气的受控反应消除一氧化碳等有毒气体。新兴的信息技术利用材料中的氧气传输来开发高密度数字存储设备。通过利用陶瓷的特殊性能，可以根据需要吸收、传输和选择性释放氧气，从而实现更高的数据存储容量、更高的能源效率和更清洁的环境，因此有可能更好地控制和操纵氧气。这个项目的研究探索了氧气是如何从陶瓷中结合、运输和释放的。陶瓷被认为在表面有特定的位置，在那里氧气(来自空气)可以很容易地进入材料。使用新开发的足以看到原子的显微镜，结合先进的计算方法，该项目正在寻找这些入口点，并将利用这些信息来设计显著提高氧交换速率的新材料类别。氧在陶瓷中的传输可以通过纳米尺度的内部边界来显著减慢。了解氧与这些内部边界相互作用的方式，为开发具有高氧传输、影响传感器、膜(用于气体和液体分离)和燃料电池等领域的新材料提供了路线图。这项研究涉及材料科学的基本概念，并为积极参与该项目所有方面的本科生和研究生提供了极好的培训机会。特别是，他们在先进材料、显微镜和计算方法领域获得了专业知识。毕业生通常会在数字技术行业、材料表征、基础研究设施和学术界找到工作。技术细节：氧化物陶瓷中的氧交换和传输有可能显著改进与能源、环境和数据存储相关的技术。这些改进的关键是需要从根本上理解气体分子中的氧气如何与陶瓷表面交换并结合到晶格中。表面结构，如台阶和张紧的原子平台，可能是氧交换最容易进行的地方。动态原位原子分辨电子显微镜的最新进展使人们能够实时地在陶瓷表面观察原子交换过程。这项研究的一个主要目标是确定氧交换最活跃的表面位置，并设计出最大限度地提高交换速率的新材料表面。氧在多晶陶瓷中的传输常常因晶界的存在而受到阻碍。在晶界掺杂高浓度的阳离子可以改善晶界的离子导电性，但其原因尚不清楚。为了了解重掺杂晶界输运改善的机理，人们结合分子和量子力学理论进行了广泛的材料模拟。最终，这一策略允许识别与最高输运相关的元素，使晶界工程方法能够开发出更快的离子导体。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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: Many important technologies rely on the ability to utilize and manipulate oxygen. For example, most energy arises from oxygen reacting with fuels through combustion processes. Environmental technologies, such as the automotive catalytic converter, eliminate toxic gases like carbon monoxide through controlled reactions with oxygen. Emerging information technologies utilize oxygen transport in materials to develop high-density digital storage devices. There is potential for much better control and manipulation of oxygen by exploiting special properties of ceramics that can absorb, transport, and selectively release oxygen on demand, leading to higher data storage capacities, greater energy efficiencies, and a cleaner environment. The research in this project explores how oxygen can be incorporated, transported, and released from ceramics. Ceramics are believed to have specific sites on the surface where oxygen (from air) can easily enter the material. Using newly developed microscopes powerful enough to see atoms, in conjunction with advanced computational methods, this project is searching for these entry points and will use this information to design new classes of materials that significantly enhance oxygen exchange rates. Oxygen transport within the ceramic can be dramatically slowed down by nanoscale internal boundaries. Understanding the way in which oxygen can interact with these internal boundaries provides a roadmap for developing new materials with high oxygen transport, impacting areas such as sensors, membranes (used in gas and liquid separations), and fuel cells. This research addresses foundational concepts in materials science and provides excellent training opportunities for undergraduate and graduate students who are actively involved in all aspects of the project. In particular, they are gaining expertise in the areas of advanced materials, microscopy, and computational methods. Graduates will typically find employment in the digital technology industry, materials characterization, basic research facilities, and academia. TECHNICAL DETAILS: Oxygen exchange and transport within oxide ceramics has the potential to significantly improve technologies related to energy, the environment, and data storage. Critical to these improvements is the need to develop a fundamental understanding of how oxygen from gas molecules exchanges with a ceramic surface and incorporates into the crystal lattice. Surface structures such as steps and strained atomic terraces are the likely sites where oxygen exchange is most facile. Recent advances in dynamic in situ atomic-resolution electron microscopy allows atomic exchange processes to be visualized on the surface of a ceramic in real time. A major goal of this research is to identify the surface sites which are most active for oxygen exchange and to engineer new materials surfaces which maximize the exchange rate. Transport of oxygen through polycrystalline ceramics is often hindered by the presence of grain boundaries. Doping the grain boundaries with high concentrations of selected cations can improve the grain boundary ionic conductivity, but the reason for the enhancement is not yet understood. To understand the mechanistic origin for the improvement in transport through heavily doped grain boundaries, extensive materials modeling is being carried out using a combination of molecular and quantum mechanical theories. Ultimately, this tactic allows the elements associated with the highest transport to be identified, enabling grain boundary engineering approaches to be developed to create much faster ion conductors.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.