First-principles design of strongly anharmonic crystalline solids with ultra-low lattice thermal conductivity

超低晶格热导率强非谐晶体固体的第一性原理设计

• 批准号: 1611507
• 负责人: Vidvuds Ozolins
• 金额: $ 30.9万
• 依托单位: Yale University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-03-15 至 2020-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1611507&HistoricalAwards=false
• 关键词: First; principles; design; strongly; anharmonic

NONTECHNICAL SUMMARYThis award supports computational research and education to advance predictive modeling of thermal transport properties of insulating and semiconducting materials. Fossil fuels (petroleum, coal, and natural gas) account for the vast majority of the energy use in the world. Less than 1/3 of the total energy content is used productively, while the rest is rejected, mainly in the form of waste heat. In the US alone, the amount of this wasted energy is roughly equivalent to that contained in 400 billion gallons of gasoline. Many technologies for improving energy efficiency, or reusing the waste heat, depend on the availability of thermally insulating ceramics and semiconductors. For instance, thermoelectrics convert heat into electricity via a phenomenon called the Seebeck effect, which operates between a hot and a cold electrode. High-performance thermoelectric devices require materials that are poor conductors of heat but efficient conductors of electricity. Currently, few such materials are known, which prevents a wider adoption of this energy-saving technology. Similarly, better ceramic thermal insulators would save energy by enabling increased operating temperatures in combustion engines.Heat in nonmetallic crystals is conducted by atomic vibrations, such as sound waves. Conventional semiconductors (e.g. silicon) are poor thermal insulators because these waves propagate independently of each other and encounter little resistance. Empirical methods for decreasing thermal conductivity aim to impede the forward movement of vibrational waves. However, these approaches require complex preparation methods and are often limited in efficiency. The PI and his group will design materials that have intrinsically low thermal conductivity because the heat-carrying waves of atomic vibrations scatter off of each other. In select solids, this scattering can become so strong that the flow of heat reaches the lowest possible value associated with glasses and amorphous solids. The project will advance computational techniques and quantum mechanical concepts for identifying and deliberately creating thermally insulating solids with desired properties.The broader impacts of the proposed research are several-fold, involving broad dissemination of research results, education of graduate students in a rich multidisciplinary environment, and introduction of undergraduate students to modern computational methods. Successful completion of this research program will contribute to the development of new thermally insulating materials as thermoelectrics and coatings with potential benefits in energy conservation. The calculated thermal properties will be disseminated to the scientific and technical community by partnering with existing online databases of computed materials data.TECHNICAL SUMMARYThis award supports research and education to advance predictive modeling of thermal transport properties of crystalline insulators and semiconductors via the development of computational methods and theoretical concepts for lowering lattice thermal conductivity. The PI and his group are mainly interested in strongly anharmonic solids where intrinsic phonon-phonon interactions limit thermal conductivity to values near the amorphous limit; such materials are of interest in energy conservation and waste-heat recovery as ceramic coatings and thermoelectrics. The PI's quantum-mechanics-based design strategy involves the use of lone-pair electrons that host anharmonic bonds, oxides, and oxosulfides of transition-metals that host strong p-d electronic hybridization effects, high-symmetry solids with ions near electronic Jahn-Teller instabilities, and compounds with frustrated structural coordination. These approaches are based on fundamental principles for enhancing intrinsic phonon scattering in crystalline materials via a mechanism that is independent of processing, impurities, and grain structure. This will allow the attainment of minimal lattice thermal conductivity in bulk oxides and semiconductors.To enable accurate computation of thermal properties, the group will pursue the following theoretical developments: (1) compressive-sensing-based methods for building lattice dynamical Hamiltonians for compositionally disordered materials, (2) efficient path integral molecular dynamics techniques for calculating low-temperature thermal transport properties of strongly anharmonic solids, and (3) electronic structure techniques for treating adiabatic lattice dynamics of solids with competing orbital ordering states in partially filled d-and f-electron shells. These methods will form a comprehensive suite of computational techniques for first-principles studies of thermal transport in anharmonic solids.The proposed work is expected to improve fundamental understanding of the thermal transport properties of strongly anharmonic materials, advance the theory and software tools for modeling thermal transport properties of solids, and provide a theoretical basis for rational design of materials with low thermal conductivity. The broader impacts of the proposed research are several-fold, involving broad dissemination of research results, education of graduate students in a rich multidisciplinary environment, and introduction of undergraduate students to modern computational methods. Successful completion of this research program will contribute to the development of new thermally insulating materials as thermoelectrics and coatings with potential benefits in energy conservation. The calculated thermal properties will be disseminated to the scientific and technical community by partnering with existing online databases of computed materials data.

该奖项支持计算研究和教育，以推进绝缘和半导体材料热传输特性的预测建模。化石燃料（石油、煤和天然气）占世界能源使用的绝大多数。只有不到1/3的总能量被有效地利用，其余的则主要以废热的形式被丢弃。仅在美国，这种浪费的能量就大致相当于4000亿加仑汽油中所含的能量。许多提高能源效率或再利用废热的技术都依赖于隔热陶瓷和半导体的可用性。例如，热电通过一种称为塞贝克效应的现象将热量转化为电能，这种现象在热电极和冷电极之间起作用。高性能热电装置需要热的不良导体但电的有效导体的材料。目前，已知的这种材料很少，这阻碍了这种节能技术的广泛采用。类似地，更好的陶瓷隔热体可以通过提高内燃机的工作温度来节省能源。非金属晶体中的热量通过原子振动（如声波）传导。传统的半导体（例如硅）是差的热绝缘体，因为这些波彼此独立地传播，遇到的阻力很小。减少导热性的经验方法旨在阻止振动波的向前运动。然而，这些方法需要复杂的制备方法，并且通常效率有限。PI和他的团队将设计具有固有低热导率的材料，因为原子振动的载热波会相互散射。在选定的固体中，这种散射可以变得如此强烈，以至于热流达到与玻璃和无定形固体相关的最低可能值。该项目将推进计算技术和量子力学概念，以识别和故意创造具有所需特性的绝热固体。拟议研究的更广泛影响是多方面的，涉及广泛传播研究成果，在丰富的多学科环境中教育研究生，并向本科生介绍现代计算方法。该研究项目的成功完成将有助于开发具有节能潜力的新型热绝缘材料，如热电材料和涂料。计算的热性能将通过与现有的在线计算材料数据库合作传播给科学和技术界。技术总结该奖项支持研究和教育，通过发展降低晶格热导率的计算方法和理论概念，推进晶体绝缘体和半导体热传输性能的预测建模。PI和他的团队主要对强非谐固体感兴趣，其中固有的声子-声子相互作用将热导率限制在接近非晶极限的值;这些材料在节能和废热回收方面具有重要意义，如陶瓷涂层和热电。PI基于量子力学的设计策略涉及使用具有非谐键的孤对电子，具有强p-d电子杂化效应的过渡金属的氧化物和氧硫化物，具有电子Jahn-Teller不稳定性附近离子的高对称固体，以及具有受挫结构配位的化合物。这些方法是基于基本原理，用于增强晶体材料中的固有声子散射，通过一种机制，是独立的处理，杂质和晶粒结构。这将使块状氧化物和半导体的晶格热导率达到最小。为了能够精确计算热性能，该小组将致力于以下理论发展：（1）用于构建组成无序材料的晶格动力学哈密顿量的基于压缩感测的方法，（2）计算强非谐固体低温热输运性质的有效路径积分分子动力学方法，和（3）用于处理在部分填充的d-和f-电子壳层中具有竞争轨道有序态的固体的绝热晶格动力学的电子结构技术。这些方法将为非谐固体热输运的第一性原理研究提供一套完整的计算技术，有助于加深对强非谐材料热输运性质的基本认识，促进固体热输运性质模拟的理论和软件工具的发展，并为低导热材料的合理设计提供理论基础.拟议的研究的更广泛的影响是几倍，涉及广泛传播的研究成果，在丰富的多学科环境中的研究生教育，并介绍了本科生的现代计算方法。该研究项目的成功完成将有助于开发具有节能潜力的新型热绝缘材料，如热电材料和涂料。计算的热性能将通过与现有的计算材料数据在线数据库合作，传播给科技界。