Origin of the low thermal conductivity of the thermoelectric material β-Zn_4Sb_3∶An ab initio theoretical study

摘要

By modeling β-Zn_4Sb_3 material as a Zn_(36)Sb_(30) crystal with defects, the crystal structure and thermal properties of β-Zn_4Sb_3 are studied by ab initio method to explain its extremely low thermal conductivity at moderate temperature. The formation and migration energies of defects are calculated and used to explain the partial occupation of Zn at the lattice sites, the disordered local structures and the origin of the low thermal conductivity of β-Zn_4Sb_3. Our study also unravels the puzzling dependence of thermal conductivity on doping in β-Zn_4Sb_3. A doping strategy is proposed to improve the thermoelectric performance of β-Zn_4Sb_3.