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

Abstract

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 μW 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 ∼15.6 W cm−2 and leg efficiency ≈14% can be obtained by calculation assuming the leg length of 2 mm, hot-side temperature Th = 800 K, and cold-side temperature Tc = 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.