石墨炔纳米结构热输运性质的理论研究

Graphyne, a new two-dimensional nanomaterial containing both sp and sp2 hybridization state, is a new hotspot in recent nanoresearch community. Owning to the existence of sp hybridization state, the graphyne possesses more various geometrical structures as well as more fascinating optoelectronic properties than graphene. The experimental researches demonstrate that these excellent physical properties presented in graphyne foreshow its great potential applications ranging from the micro-nano devices to energy storage. Nevertheless, the previous studies on the fundamental physical properties of graphyne are mainly focus on the electronic and optical properties. The thermal transport properties of graphyne have not received much significant attention until now. In this project, the thermal transport properties of graphyne nanostructures will be studied by using the first principle calculation and nonequilibrium Green's-function method. The intrinsic relation between phonon transport and some influence factors, such as edge type, topological structure, geometrical size, defect and impurity, will be discussed profoundly. Moreover, the fundamental law of the phonon scattering in graphyne nanostructures will be summarized as well. Through systematical analysis and study, some novel thermal transport phenomena in graphyne will be discovered and its microscopic physical mechanism will be revealed, meanwhile the physical models for modulating the thermal transport properties of graphyne will be established. The Completion of this project will not only deepen our knowledge and understanding on the thermal properties of carbon-based nanomaterials, but also provide theoretical basis and experimental guidance for the design and development of graphyne-based micro-nano devices.

石墨炔，一种由sp和sp2两种杂化态构成的新型二维碳纳米材料，是现今纳米研究领域的一个新热点。源于sp杂化态的出现，石墨炔展现出比石墨烯更为多样的几何构型和更为优异的光电性质。实验研究表明这些新颖的物理属性预示着石墨炔在微纳器件以及能量存储方面具有广泛的应用前景。然而，目前对石墨炔基本物理属性的研究主要集中在光电性质方面，有关其热输运特性的研究还鲜有报道。本项目拟采用第一性原理结合非平衡格林函数方法研究石墨炔纳米结构中的热输运特性，分析边缘类型、拓扑结构、几何尺寸、缺陷、杂质等因素与石墨炔声子输运性质的内在关联，总结石墨炔纳米结构声子散射的基本规律。通过系统的分析和探讨，发现石墨炔纳米结构中的新奇热输运现象并揭示其微观物理机制，构建调控石墨炔热输运特性的物理模型。本项目的开展不但可以深化对碳基纳米材料热性质的认识和理解，同时也可为设计和发展基于石墨炔的微纳器件提供理论基础和实验指导。

石墨炔，一种由sp和sp2两种杂化态构成的新型二维碳纳米材料，是现今纳米研究领域的一个新热点。本项目通过对石墨炔纳米结构、类石墨炔多孔碳纳米结构以及新型热电材料的热输运性质进行系统的研究和探讨，阐明了边缘类型、拓扑结构、几何尺寸、缺陷等因素对其热及热电输运调控作用的微观物理机制，丰富了人们对纳米材料中声子、电子输运规律的认识和理解，为石墨炔及其相关材料在微纳器件、热电转换、热控制等领域的应用提供物理模型和理论参考。围绕“石墨炔纳米结构中的热输运性质”这一核心问题，本项目在以下三个方面取得了一些研究进展：1、我们研究发现Beta-石墨炔纳米带具有显著的热各向异性，并且其热电性能要远优于其姊妹材料——石墨烯（室温下beta-石墨炔热电品质因子可以达到0.5，而石墨烯仅为0.05左右），该结果说明Beta-石墨炔有望成为新一代的碳基热电材料。2、我们研究发现通过结构调制（例如：缺陷、嵌入量子点）能有效地提高石墨炔的热电品质因子，这一现象主要源于结构调制能极大地削弱系统的热输运性质而能较好地保留系统中原有的电子性质。该部分结果为基于石墨炔的热电器件设计及制备提供了强有力的理论指导。3、我们还拓展了对含氮多孔石墨烯，Alpha-碲化银，Wyle半金属材料TaAs以及碲化物XTe(X=Hg, Cd, Zn)热输运性质的研究，揭示了这些新型材料的声子输运特性及其微观物理机制，例如：我们发现TaAs为显著的热各向异性材料，含氮多孔石墨烯中声学声子及光学声子的相互作用主导了三声子散射过程，而在HgTe中我们发现了非常反常的负压强依赖热导。这些发现为相关材料在热控制领域的应用奠定了可靠的理论基础。