Ultralow Lattice Thermal Conductivity and High Thermoelectric Figure of Merit in Dually Substituted Cu<sub>12</sub>Sb<sub>4</sub>S<sub>13</sub> Tetrahedrites
Chen Zhu, Hongwei Ming, Jian Zhang, Di Li, Tao Chen, Xiaoying Qin
Abstract
Abstract The thermoelectric properties of dually substituted Cu 12− x In x Sb 4 S 12.8 Se 0.2 tetrahedrites are studied in temperature range from 300 to 723 K. The results indicate that dual substitution of In for Cu and Se for S not only causes the enhancement of thermopower S but also gives rise to a significant decrease in lattice thermal conductivity κ L . An ultralow κ L ≈0.2 W m −1 K −1 is obtained at 723 K in Cu 11.95 In 0.05 Sb 4 S 12.8 Se 0.2 sample due to the enhanced phonon scattering mainly by point defects. Consequently, a high figure of merit ZT max ≈1.0 is achieved in Cu 11.95 In 0.05 Sb 4 S 12.8 Se 0.2 sample, which is ≈56% larger than that of pristine Cu 12 Sb 4 S 13 , indicating that dual substitution is effective in boosting the thermoelectric properties of tetrahedrites.