First Principles Studies of Novel Approach for Achieving Ultrahigh Thermal Conductivity in Materials

CBET-1402949 Broido随着微电子设备的不断缩小，散热正成为一个日益关键的技术挑战。为了应对这一挑战，迫切需要高导热材料。长期以来，碳基晶体、钻石、石墨、石墨烯和碳纳米管一直被认为是所有材料中导热系数最高的。尤其是金刚石，被广泛用于电子设备的被动冷却，但其合成制造存在生长速度慢、成本高、质量低等缺点。尽管有明确的标准来指导寻找新的高性能材料，但多年来进展甚微。使用精确的第一性原理的理论方法，我们最近发现了一种意想不到的材料，砷化硼应该具有非常高的导热系数，可以与钻石相媲美。这一令人惊讶的发现源于材料的基本性质，其中一些性质通常与材料中高含量的配方无关。该项目的目标将是详细研究砷化硼的热传输特性，并使用为砷化硼确定的材料搜索范式来确定新的高性能材料。因此，该项目将通过帮助开发新型高性能材料，帮助解决散热挑战并造福社会。这将促进可能导致下一代电子被动冷却设备(如散热器和散热器)的技术突破。这项研究工作将实施最先进的第一原理热传输方法，以提供对我们最近发现的异常高的砷化硼的基本理解，以及为实现材料的高导热系数而提出的新范式。这种方法的一个主要特点是它没有可调整的参数。此外，它已经表现出与广泛材料的测量导热系数的良好一致性，验证了其预测能力。结合了在砷化硼中发现的新材料特性的高效计算算法将被用于实现对一类新的高性能材料的广泛搜索。这将有助于发现尚未确定的高能材料。我们还将更深入地了解缺陷的作用，并深入了解如何调整所需的材料性能以增强性能。该项目提供了对材料导热性质的重要新见解，为测量工作提供指导，并促进用于热管理应用的高材料的设计和开发。

CBET-1402949BroidoAs microelectronic devices continue to shrink, heat dissipation is becoming an increasingly critical technology challenge. High thermal conductivity materials are urgently needed to address this challenge. The carbon-based crystals, diamond, graphite, graphene and carbon nanotubes have long been known to have by far the highest thermal conductivities, κ, of any material. Diamond, in particular, is widely used for passive cooling of electronics, but its synthetic fabrication suffers from slow growth rates, high cost, and low quality. In spite of well-defined criteria to guide the search for new high κ materials, little progress has been made over the years. Using an accurate, first principles, theoretical approach, we have recently found that an unexpected material, boron arsenide should have exceptionally high thermal conductivity, comparable to that of diamond. This surprising finding stems from fundamental material properties, some of which are not typically connected to prescriptions for high κ in materials. The objectives of this project will be to study in detail the thermal transport properties of boron arsenide, and to identify new high κ materials using the materials search paradigm identified for boron arsenide. This project will therefore help address the heat dissipation challenge and benefit society by aiding in the development of new high κ materials. This will facilitate technological breakthroughs that may lead to the next generation of passive cooling devices for electronics, such as heat spreaders and heat sinks.This research effort will implement a state-of-the-art, first principles thermal transport approach to provide fundamental understanding of our recent finding of exceptionally high κ in boron arsenide and the proposed new paradigm for achieving high thermal conductivity in materials. A central feature of this approach is that it has no adjustable parameters. Furthermore, it has already demonstrated excellent agreement with measured thermal conductivities for a wide range of materials, validating its predictive capability. Efficient computational algorithms incorporating the novel material properties found in boron arsenide will be used to implement a broad search for a new class of novel high κ materials. This will facilitate the discovery of as yet unidentified high κ materials. Deeper understanding of the role of defects and insight into how to tune the desirable material properties to enhance κ will also be investigated. This project with provide important new insights into the nature of thermal conductivity in materials, give guidance to measurement efforts, and facilitate the design and of high κ materials for thermal management applications.