碳化硼纳米线的声子输运特性及在高温热电中的应用研究

项目名称： 碳化硼纳米线的声子输运特性及在高温热电中的应用研究

项目编号： No.51276153

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 能源与动力工程

项目作者： 徐东艳

作者单位： 香港中文大学深圳研究院

项目金额： 80万元

中文摘要： 热电器件可直接将热能转化为电能，在余热回收中有巨大的应用潜力，但目前受限于其较低的转换效率。近来研究发现，采用纳米结构，如超晶格、纳米线、以及纳米复合材料等，可大大提高热电转换效率，这主要归功于这些结构低的导热系数。碳化硼是一类具有复杂晶格结构的高温热电材料。可以预计，碳化硼纳米线具有更低的导热系数，因而可以得到更好的热电性能。然而到目前为止，还没有关于低维碳化硼纳米结构热电性能的研究报道。本项目以实验为主要手段，结合理论分析，对碳化硼纳米线的声子输运特性进行系统地研究，阐明碳含量、结构缺陷、以及纳米线直径等对碳化硼纳米线导热系数的影响。另外，为确定碳化硼纳米线的热电品质系数，我们还将测量纳米线的电导率及Seebeck系数。本项目的开展有助于揭示具有复杂晶格结构的低维纳米材料中声子的输运特性，推动高温热电材料的研究。

中文关键词： 声子传输；热电；碳化硼；纳米线；弯曲段

英文摘要： Thermoelectric devices show a great potential for waste heat recovery by directly converting heat into electricity; however, to date their practical applications have been limited by their low efficiencies. Recently, several reports demonstrated significantly improved thermoelectric efficiencies by engineering thermoelectric materials into nanostructures, such as superlattices, nanowires, and nanocomposites, primarily through thermal conductivity reduction. Boron carbide is a class of high-temperature thermoelectric materials with complex crystal structures. Based on recent advances of thermoelectric nanomaterials, we know boron carbide nanowires may have enhanced thermoelectric performance through reduced thermal conductivity. However, the thermoelectric properties of low-dimensional boron carbide nanostructures have yet to be explored. The objective of the proposed research is to understand phonon transport in boron carbide nanowires through systematic measurements at individual nanostructure level combined with theoretical modeling for thermoelectric energy conversion applications. We will clarify the effects of carbon concentration, planar defect morphology, and nanowire diameter on thermal conductivities of individual boron carbide nanowires. Moreover, the electrical conductivity and Seebeck coeffici

英文关键词： Phonon Transport；Thermoelectrics；Boron Carbides；Nanowire；Kink