Thermoelectric Properties in the Cu Doping Effects of the n-type Bi-Te Powders

Abstract

<p>Bi2Te3 related compounds show the best thermoelectric properties at room temperature. However, n-type Bi2Te2.7Se0.3 showed no improvement on ZT values. To improve the thermolectric propterties of n-type Bi2Te2.7Se0.3, this research has Cu-doped n-type powder. This study focused on effects of Cu-doping method on the thermoelectric properties of n-type materials, and evaluated the comparison between the Cu chemical and mechanical doping. The synthesized powder was manufactured by the spark plasma sintering(SPS). The thermoelectric properties of the sintered body were evaluated by measuring their Seebeck coefficient, electrical resistivity, thermal conductivity, and hall coefficient. An introduction of a small amount of Cu reduced the thermal conductivity and improved the electrical properties with Seebeck coefficient. The authors provided the optimal concentration of Cu<sub>0.1</sub>Bi<sub>1.99</sub>Se<sub>0.3</sub>Te<sub>2.7</sub>. A figure of merit (ZT) value of 1.22 was obtained for Cu<sub>0.1</sub>Bi<sub>1.9</sub>Se<sub>0.3</sub>Te<sub>2.7</sub> at 373K by Cu chemical doping, which was obviously higher than those of Cu<sub>0.1</sub>Bi<sub>1.9</sub>Se<sub>0.3</sub>Te<sub>2.7</sub> at 373K by Cu mechanical doping (ZT=0.56) and Cu-free Bi<sub>2</sub>Se<sub>0.3</sub>Te<sub>2.7</sub> (ZT=0.51).</p>