原子/分子接触的热电转换效率及其输运性质的研究

项目名称： 原子/分子接触的热电转换效率及其输运性质的研究

项目编号： No.51476033

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 能源与动力工程

项目作者： 王建立

作者单位： 东南大学

项目金额： 80万元

中文摘要： 原子/分子接触是原子操作、纳米热电转换利用等技术的关键问题，由于其特殊的能量输运过程而受到广泛关注。项目拟制备用于纳米线热物性测量的微器件装置，构建具有稳定磁场的低温真空实验系统，测量80-300K温度范围内纳米线热导率随长度、直径以及磁场强度的变化；采用自组装单分子膜技术对纳米线表面进行处理，通过磁场下的洛伦玆力实现原子/分子接触过程的准确控制，统计大量接触过程中的电流-电压曲线，测得接触电导的量子效应，结合3ω法和2ω法，得到对应的Seebeck系数，并在交叉纳米线结构的基础上，测得接触热导，进而实现原子/分子接触中热电转换优值系数的实验测量；利用商用软件计算电子能带结构，采用非平衡格林函数法得到透射系数，根据Landauer理论分析材料结构、尺寸等因素对优值系数的影响；结合实验测量和理论计算结果，揭示原子/分子接触过程中热电输运的本质规律，从而为低维材料器件化提供重要的科学依据。

中文关键词： 接触传热；纳米材料；洛伦玆力；热电转换；优值系数

英文摘要： The atomic and molecular contacts are the most important issues in various technological applications, such as the atomic-scale manipulation, nanoscale thermoelectric conversion and etc, and there has been an increasing interest in their unusual energy transport phenomena. The project tends to fabricate a microscale device, which can be used to measure the thermal properties of nanowires. A cryogenic system with the presence of a stable magnetic field will be established. At different magnetic density, the dependence of the thermal conductivity of metallic nanowire on its structures, such as length and diameter, is measured in the temperature range from 80 to 300 K. The self-assembly technique is applied to form a desired molecular layer on the target nanowires, and the atomic and molecular contact process is controlled accurately with the aid of the Lorentz force. By monitoring a large amount of the current-voltage curves, the quantized electrical contact conductance can be statistically obtained. Combined with the 3ω method and 2ω method, the corresponding Seebeck coefficient is obtained, and the thermal conductance is measured based on the crosswise structure formed by two nanowires. Finally, the figure of merit at the atomic and molecular contacts is exprimental obtained. The ab initio electronic structure calculations are based on the implementation of density functional theroy in commercial software, the transmission function is given by the nonequilibrium Green's function techniques, so the transport properties of the atomic and molecular contacts are calculated using the Landauer theory, and the effects of the molecular structure and dimensions on the figure of merit are analyzed. Based on the experimental and theoretical results, the energy conversion and transport mechanisms through the atomic and molecular contacts are confirmed, which in turns provides an important scientific support in devices synthesized by low dimensional materials.

英文关键词： contact heat transfer;nanomaterial;Lorentz force;thermoelectric conversion;figure of merit