Properties of hot-pressed Bi-Sb-Te compounds with non-uniform Ag doping

• Main Authors: Kuo, Po-Wei, 郭柏瑋
• Other Authors: Liao, Chien-Neng
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/93368320939100611493

碩士 === 國立清華大學 === 材料科學工程學系 === 101 === Thermoelectric materials that can convert thermal energy to electric energy and vice versa have been applied in applications of waste-heat recovery and refrigeration. In most thermoelectric devices, the directions of temperature gradient and electric field are the same. In this research, a longitudinal temperature gradient introduces a lateral electric field, which is called transverse Seebeck effect, has been found in hot-pressed Bi0.4Sb1.6Te3 sample with non-uniform Ag doping. The property of uncoupling heat flow and electric flow directions may provide ideas of developing different device applications. The thermoelectric properties of both Ag-doped and non-doped Bi-Sb-Te samples have been determined experimentally. The transverse Seebeck effect has been found in non-uniform Ag doping sample with asymmetric transverse voltage in hot side and cold side by a self-designed transverse Seebeck measurement apparatus. The experimental and simulation results shows that transverse Seebeck effect should have been referred to different voltage drops between Ag-doped region and non-doped region. Asymmetric transverse voltage may be related to larger charged carrier flow at high temperature side, which has been expressed as an empirical term jemp in simulation. The experimental and simulation results have applied a preliminary model of transverse thermoelectric effect specimen fabrication. The transverse Seebeck coefficient has reached 120 μV/K in simulation.