热电效应能够实现热能和电能的直接转换，在废热发电和电子器件散热等领域拥有广阔的应用空间。低维和纳米化是提高材料热电性能的重要途径，在新型微纳米热电材料的开发过程中，对其热电性能的准确表征和研究具有重要意义。本文实验测量了EuBiSe3纤维、掺溴石墨烯纤维和单根Sb2Se3纳米线等新型微纳米线材的电导率、热导率和塞贝克系数，研究了影响其热电性能的微观物理机制。本文的研究工作有望为新型微纳米结构热电材料的开发提供实验依据和理论指导。本文采用综合T型法对同一微纳米线材的电导率、热导率和塞贝克系数进行综合表征。基于综合T型法，提出了“三线法”用于测量微纳米线材的电导率、热导率和塞贝克系数，减小了接触热阻的影响，利用R型热电偶丝校验了“三线法”的测量精度。测量了EuBiSe3纤维电导率、热导率和塞贝克系数随环境温度的变化，分析了稀土元素对材料热电性能的影响机制。研究发现，稀土元素Eu引入了大量点缺陷，增加了费米能级附近的态密度。对比Bi2Se3，EuBiSe3纤维的电导率、热导率和塞贝克系数同时提高，290 K时ZT值为0.05。测量了掺溴石墨烯纤维电导率、热导率和塞贝克系数随环境温度的变化，揭示了元素掺杂对材料热电性能的影响。研究发现，溴掺杂降低了石墨烯纤维的费米能级，产生了大量空穴，提高了电输运性能；掺杂引入大量杂质和缺陷，降低了纤维的晶格热导率；与纯石墨烯纤维相比，掺溴石墨烯纤维的ZT值提升了四个量级，达到0.00276，元素掺杂是提高石墨烯基材料热电性能的有效途径。测量了单根Sb2Se3纳米线电导率、热导率随环境温度的变化关系和室温下的塞贝克系数，研究了纳米化对材料热电性能的影响机制。研究发现，所测Sb2Se3纳米线为N型半导体，部分Se元素作为施主杂质引入了施主能级，极大提高了材料的电导率；热导率的温度依赖特性主要受声子-边界散射影响，较好的晶体结构导致材料的晶格热导率并无明显降低；室温下Sb2Se3纳米线的塞贝克系数为?1120 μV K-1，ZT值为0.064，并未体现出特别优异的热电性能，有望通过增加点缺陷、提高掺杂度等方式进一步提升。
Thermoelectric materials enables direct conversion of thermal energy and electric energy and show great promise in cogeneration and electronic device cooling. Low-dimension and nanoscale materials are more likely to process high thermoelectric properties and have become the main research direction. Accuately characterize the thermoelectric properties of new developed materials is of great significance. This paper measured electrical conductivity, thermal conductivity and Seebeck coefficient of several new developed micro/nano wires such as EuBiSe3 fiber, bromine-doped graphene fiber and single Sb2Se3 nanowire. The correspongding influencing machanisms on the thermoelectric properties are also explored. This work is expected to provide experimental evidence and theoretical guidance to the development of new micro/nanostructured thermoelectric materials.This paper used a comprehensive T-type method to measure the electrical conductivity, thermal conductivity and Seebeck coefficient simultaneously of the same micro/nanoscale wire. Based on the comprehensive T-type method, a three-wire method was further developed to comprehensively measure electrical conductivity, thermal conductivity and Seebeck coefficient of micro/nanoscale wires. The influence of contact thermal resistance is reduced and an R-type thermocouple wire was used to verify the measurement accuracy.The electrical conductivity, thermal conductivity and Seebeck coefficient of EuBiSe3 fiber have been measured at different temperature, and the influence of rare earth element has been revealed. The results show that the rare earth element Eu introduces point defects and increases the density of states near the Fermi level. Compared with Bi2Se3, the electrical conductivity, thermal conductivity and Seebeck coefficient of the EuBiSe3 fiber increase simultaneously and obtain a ZT value of 0.05 at 290 K. The electrical conductivity, thermal conductivity and Seebeck coefficient of bromine-doped graphene fiber have been measured at different temperature. The Study show that bromine doping reduces the Fermi level of graphene fiber and produces a large number of holes. The electrical transport properties of bromine-doped graphene fiber is increased. At the same time, the doping introduces a large amount of impurities and defects, which reduces the lattice thermal conductivity. Compared with the pure graphene fiber, the ZT value of the bromine-doped graphene fiber increases by four orders of magnitude to 0.00276. The electrical conductivity and thermal conductivity of single Sb2Se3 nanowire have been measured at different temperature while the Seebeck coefficient was measured at room temperature. The results show that the measured nanowire is n-type doped. The shallow donor levels near the conduction band edge improves the electrical conductivity of the material. The thermal conductivity of Sb2Se3 nanowire is mainly dominated by phonon-boundary scattering. At room temperature, the ZT value of Sb2Se3 nanowire reaches 0.064 with a Seebeck coefficient of ?1120 μV K-1. The measured Sb2Se3 nanowires do not exhibit excellent thermoelectric properties and the further improvement is expected to be realized by increasing dot defects and doping levels.
