High thermoelectric performance from high carrier mobility and reduced lattice thermal conductivity in Ba, Yb double-filled Skutterudites

The semicoherent low-angle grain boundaries with dense dislocation arrays have been confirmed as an effective way to improve the thermoelectric properties for Yb single-filled Skutterudites using liquid-phase compaction method in our previous work. It is known that fillers with different rattling frequencies can scatter a wider spectrum of phonons, leading to further reduced lattice thermal conductivity. Thus, on the basis of liquid-phase compaction method, Ba, Yb double-filled Skutterudites were successfully synthesized. Ba, Yb double filling and liquid-phase compaction method synergistically optimize carrier concentration and reduce lattice thermal conductivity, resulting in exceptional high PF of 57 mu W cm(-1) K-2 at 773 K and excellent thermoelectric figure of merit ZT = 1.53 at 823 K. Correspondingly, the high theoretical output power density similar to 15.6 W cm(-2) and leg efficiency approximate to 14 can be obtained by calculation assuming the leg length of 2 mm, hot-side temperature T-h = 800 K, and cold-side temperature T-c = 300 K. This work highlights that the obtained Skutterudites display great promise for harvesting electricity from waste heat with heat source at the medium temperature range. (C) 2019 Elsevier Ltd. All rights reserved.