SCIENCE CHINA Materials
The equivalent and aliovalent dopants boosting the thermoelectric properties of YbMg2Sb2
Xinxin Yang, Yayun Gu, Yuping Li, Kai Guo, Jiye Zhang, Jing-Tai Zhao
Antimony-based Zintl compounds AM2Sb2 (A=Ca, Sr, Ba, Yb, Eu; M=Mg, Zn, Cd, Mn), which enable a broad range of manipulation on electrical and thermal transport properties, are considered as an important class of thermoelectric materials. Phonon and carrier transport engineering were realized in YbMg2Sb2 via equivalent and aliovalent substitution of Zn and Ag, respectively. The room-temperature thermal conductivity reduces from 1.96 to 1.15 W m−1 K−1 for YbMg2−xZnxSb2 due to the mass and strain fluctuation through the formation of the absolute solid solution of YbMg2Sb2-YbZn2Sb2. Furthermore, the carrier concentration has been further optimized by Ag doping (from 0.42×1019 to 7.72×1019 cm−3 at room temperature), and thus the electrical conductivity and the power factor are enhanced effectively. The integrated aspects make the dimensionless figure of merit (zT) reach 0.48 at 703 K, which is 60% higher than the pristine YbMgZnSb2 sample.