Synergistic optimization of electrical and thermal transport in n-type Bi-doped PbTe by introducing coherent nanophase Cu1.75Te
Chen Zhu, Jian Zhang, Hongwei Ming, Lulu Huang, Yuanyue Li, Tao Chen, Di Li, Baoli Zhang, Jingtao Xu, Xiaoying Qin
Abstract
Based on the calculated results of band structures and density of states, Bi doping is used to adjust its carrier concentration in order to obtain n-type PbTe materials with high power factor. Then, coherent nanophase Cu1.75Te is in situ formed in the n-type PbTe matrix, which can simultaneously optimize the thermal and electrical properties. As a result, at a relative lower temperature than other reports, the highest ZT value of 1.4 is obtained at 623 K for the nominal Pb0.995Bi0.005Te+0.86 wt% Cu1.75Te sample. More importantly, the ZT hold a higher value in the broad temperature; especially, ZT value is about 1.2–1.4 in the temperature range of 573–773 K, which is beneficial to the significant average ZT value ZTave ∼ 0.9 in the temperature range of 300–773 K. These results indicate that it is an effective and feasible method to enhance the thermoelectric properties via synergistic modulation of electrical and thermal transport properties by element doping and in situ coherent nanophase.