Realizing High Thermoelectric Performance in N‐Type Mg₃(Sb, Bi)₂‐Based Materials via Synergetic Mo Addition and Sb–Bi Ratio Refining

Abstract

Developing thermoelectric (TE) performance is impeded by the compromise of TE parameters, resulting in inadequate conversion efficiency of heat to electricity. Herein, this work reports that Mo is a particularly effective additive in Mg3Sb2‐based alloys with significantly improved electronic transport via grain‐boundary engineering and band‐structure regulation synergy. In addition, phonon transport is simultaneously suppressed by employing multiple effects, lattice imperfection scattering, reduced phonon group velocity, and enhanced atomic disorder, leading to a minimum κlat = 0.52 W m−1 K−1 at 723 K. As a result, an outstanding ZT peak of ≈1.84 at 723 K and ZTav = 1.34 within 323–723 K are achieved in Mg3Sb2‐based alloys, and the corresponding fabricated single‐leg TE module shows an exceptionally high conversion efficiency of ≈12% under a hot‐side temperature of 450 °C. These results demonstrate the great potential for advancing mid‐temperature heat harvesting in Mg3Sb2‐based materials.

Wide-temperature-range thermoelectric n-type Mg3(Sb,Bi)2 with high average and peak zT values

“…17 exhibit the contribution from the modified interfacial barrier to S, where the data points deviate upward slightly. Recently, it has been reported that the Mo addition also increases the σ of Mg 3 (Sb,Bi) 2 -based materials 38 , indicating the great potential of other transition metals. However, the enhanced σ by Mo addition is mainly due to the grain boundary effect, different from those analyzed above for the Nb or Ta inclusions.…”

Rational design from materials to devices enables an efficiency of 10.5% based on thermoelectric (Bi, Sb)2Te3 and Mg3(Bi, Sb)2 for power generation

“…The figure of merit ZT is defined as ZT = S 2 σT / κ , where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature, and κ is the thermal conductivity. 3,4 To produce greater thermoelectric power generation, a large temperature difference (Δ T = T h − T c ) and a high ZT ave are desired. 5 However, the high-performance temperature range of typical TE materials is usually narrow.…”

Ultrafast Combustion Synthesis and High Thermoelectric Performance of Mg3Sb2-xBix-Based Compounds

“…Mg 3 Sb 2 -based thermoelectric materials, which consist of earth-abundant elements and are environmentally friendly, show great potential for low temperature power generation. Most recently, it has attracted great attention in the thermoelectric community, and the thermoelectric properties of Mg 3 Sb 2 -based materials have been greatly improved. − Liu et al reported that the maximum ZT values above ∼1.6 at 673 K and average ZT above ∼1.0 between 300 and 673 K are attained by Er, Dy, Gd, and Nd doping. These dopants optimize the carrier concentration, increase the density of states effective mass, and suppress the scattering of ionized impurities in Mg 3 Sb 2 -based compounds .…”