Fu Qiang, Xiong Yucheng, Zhang Wenhua, Xu Dongyan
Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong.
Rev Sci Instrum. 2017 Sep;88(9):095111. doi: 10.1063/1.4990634.
This paper presents a setup for measuring the Seebeck coefficient and the electrical resistivity of bulk thermoelectric materials. The sample holder was designed to have a compact structure and can be directly mounted in a standard cryostat system for temperature-dependent measurements. For the Seebeck coefficient measurement, a thin bar-shaped sample is mounted bridging two copper bases; and two ceramic heaters are used to generate a temperature gradient along the sample. Two type T thermocouples are used to determine both temperature and voltage differences between two widely separated points on the sample. The thermocouple junction is flattened into a disk and pressed onto the sample surface by using a spring load. The flexible fixation method we adopted not only simplifies the sample mounting process but also prevents thermal contact deterioration due to the mismatch of thermal expansion coefficients between the sample and other parts. With certain modifications, the sample holder can also be used for four-probe electrical resistivity measurements. High temperature measurements are essential for thermoelectric power generation. The experimental system we developed is capable of measuring the Seebeck coefficient and the electrical resistivity of bulk thermoelectric materials in a wide temperature range from 80 to 500 K, which can be further extended to even higher temperatures. Measurements on two standard materials, constantan and nickel, confirmed the accuracy and the reliability of the system.
本文介绍了一种用于测量块状热电材料塞贝克系数和电阻率的装置。样品架设计为结构紧凑，可直接安装在标准低温恒温器系统中进行温度相关测量。对于塞贝克系数测量，将一个细条形样品跨接在两个铜基座上；使用两个陶瓷加热器沿样品产生温度梯度。使用两个T型热电偶来确定样品上两个相距较远点之间的温度和电压差。热电偶结被压成圆盘状，并通过弹簧负载压在样品表面。我们采用的灵活固定方法不仅简化了样品安装过程，还防止了由于样品与其他部件热膨胀系数不匹配导致的热接触恶化。经过一定修改，样品架也可用于四探针电阻率测量。高温测量对于热电发电至关重要。我们开发的实验系统能够在80至500 K的宽温度范围内测量块状热电材料的塞贝克系数和电阻率，该温度范围还可进一步扩展到更高温度。对两种标准材料康铜和镍的测量证实了该系统的准确性和可靠性。
