NSF Fundamental Mechanisms for Thermal Conductivity in Complex Oxides with High-Temperature Applications

对科学和技术的更广泛影响：在高温下具有低热导率的材料对于开发用于发电和运输的更高能效发动机至关重要。新的结果表明，有前景发现材料的热导率比现有的陶瓷低得多，热导率的机制可能是从根本上不同于传统的声子散射图片在简单的晶体材料。该项目解决了识别具有更低热导率的化合物的挑战，重点是具有强各向异性热导率的层状晶体结构。我们相信，该项目将通过改进热管理材料对技术产生广泛影响，并通过在理解复杂晶体结构中的热导率方面的根本性进展对材料科学产生影响。除了重要的发现方面，我们认为我们的建议的优点在于我们的综合，这是一个合作的方法来识别候选材料从大量的氧化物化合物和理解各向异性导热性是如何与晶体结构各向异性。我们的综合实验和模拟计划的目的是超越基于直觉的爱迪生方法，以更系统的方法来发现材料。该方法的基础是将联合收割机最先进的模拟与传统的陶瓷合成和加工相结合，并结合探索成分变化的组合方法，以提供更快速的发现路径。最初的重点是复杂的，萤石衍生结构和钙钛矿相关的层状结构，具有非常低和/或强各向异性的热导率。层状晶体结构，如钙钛矿，提供了机会，以研究层是否可以阻止垂直热传输在原子水平，以及促进热传输性能和其他重要的性能标准。

Broader Impact in Science and Technology: Materials with low thermal conductivity at high temperature are crucial to the development of higher energy efficiency engines for power generation and transport. New results indicate that there is the prospect of discovering materials with much lower thermal conductivities than existing ceramics and that the mechanisms of thermal conductivity may be radically different from the conventional phonon scattering picture in simple crystalline materials. This project addresses the challenge of identifying compounds having even lower thermal conductivity with an emphasis on layered crystal structures with strongly anisotropic thermal conductivity. We believe that the project will have broad impact on technology through improved heat management materials and impact the science of materials through fundamental advances in understanding thermal conductivity in complex crystal structures.Intellectual Merit: Apart from the important discovery aspects, we believe the merit of our proposal lies in our integrated, collaborative approach to the identifying candidate materials from an enormous number of oxide compounds and an understanding how anisotropic thermal conductivity is related to crystal structure anisotropy. The aim of our integrated experimental and simulation program is to go beyond an intuition-based Edisonian approach to a more systematic approach to the discovery of materials. The basis of the approach is to combine state-of-the art simulations with both traditional synthesis and processing of ceramics together with combinatorial approaches exploring compositional variations to provide a more rapid discovery path. The initial emphasis is on complex, fluorite-derived structures and perovskite-related layered structures that have very low and/or strongly anisotropic thermal conductivities. Layered crystal structures, such as the perovskites, provide the opportunity to investigate whether the layers can impede perpendicular thermal transport at the atomic level as well as facilitating both the thermal-transport properties and other important performance criteria.