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

非技术描述：许多重要的技术依赖于利用和操纵氧气的能力。例如，大多数能量来自氧气通过燃烧过程与燃料反应。环保技术，如汽车催化转化器，通过控制与氧气的反应来消除一氧化碳等有毒气体。新兴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，可以更好地控制和操纵氧气，这些陶瓷可以根据需要吸收，运输和选择性释放氧气，从而提高数据存储容量，提高能源效率和清洁环境。该项目的研究探索了氧气如何从陶瓷中结合，运输和释放。陶瓷被认为在表面上有特定的位置，氧气（来自空气）可以很容易地进入材料。使用新开发的强大到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切入点，并将利用这些信息设计新的材料类别，显着提高氧交换率。陶瓷内的氧传输可以通过纳米级内部边界显著减慢。了解氧气与这些内部边界相互作用的方式为开发具有高氧气传输的新材料提供了路线图，影响了传感器，膜（用于气体和液体分离）和燃料电池等领域。这项研究解决了材料科学的基本概念，并为积极参与该项目各个方面的本科生和研究生提供了极好的培训机会。 特别是，他们正在获得先进材料，显微镜和计算方法领域的专业知识。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。 技术规格：氧化物陶瓷内的氧交换和传输具有显著改善与能源、环境和数据存储相关的技术的潜力。这些改进的关键是需要对气体分子中的氧如何与陶瓷表面交换并结合到晶格中有一个基本的了解。表面结构，如步骤和紧张的原子梯田是可能的网站，氧交换是最容易的。动态原位原子分辨率电子显微镜的最新进展使原子交换过程在陶瓷表面上可以真实的实时可视化。这项研究的一个主要目标是确定最活跃的氧交换表面的网站和工程新材料的表面，最大限度地提高交换率。氧通过多晶陶瓷的传输常常受到晶界存在的阻碍。用高浓度的所选阳离子掺杂晶界可以改善晶界离子电导率，但增强的原因尚不清楚。为了理解通过重掺杂晶界的传输改善的机制起源，正在使用分子和量子力学理论的组合进行广泛的材料建模。最终，这一策略允许与最高传输相关的元素被识别，使晶界工程方法得以发展，以创造更快的离子导体。该奖项反映了NSF的法定使命，并已被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.