Efficient lanthanide Gd doping promoting the thermoelectric performance of Mg3Sb2-based materials†
Abstract
Mg3Sb2-based thermoelectric materials have recently received heightened attention due to their diverse merits of high band degeneracy, ultralow lattice thermal conductivity and high carrier mobility. However, the inherently low carrier concentration of pristine Mg3Sb2 seriously hinders the advancement of this material toward high thermoelectric performance. Therefore, searching for proper dopants to optimize the carrier concentration is one of the primary avenues to realize superior thermoelectric performance in Mg3Sb2-based materials. Herein, by considering the electronegativity difference Δχ and mass difference ΔM between the dopant and host elements, we theoretically and experimentally demonstrate lanthanide Gd as an effective dopant to tune the carrier concentration of Mg3Sb1.3Bi0.7 alloys. Owing to its high doping efficiency, a large carrier concentration up to 8.9 × 1019 cm−3 is realized through Gd doping, which is close to the optimal value. Moreover, the coarse grain size commendably mitigates the grain boundary effects and thus ensures high carrier mobility. Combining the greatly suppressed lattice thermal conductivity by point defect scattering, a maximum zT of 1.55 is achieved at 700 K in Mg3.065Sb1.3Bi0.7Gd0.015.
- This article is part of the themed collection: Journal of Materials Chemistry A HOT Papers