Magnetism-induced diffuse scattering effect triggers excellent thermoelectric performance

Abstract

Mg₃(Sb,Bi)₂-based materials have attracted increasing attention owing to the comparable thermoelectric performance to state-of-the-art Bi₂Te₃-based alloys. However, their intrinsic low carrier mobility issue severely restricts their room-temperature performance. Herein, by carefully manipulating the magnetic diffuse scattering effect through Co secondary impurity incorporation, we discovered that carrier mobility can be unusually increased and lattice thermal conductivity is significantly suppressed. Negative magnetoresistance with square field dependence (H²) revealed the beneficial contribution of the magnetism-induced diffuse scattering effect to the enhancement of carrier mobility by 46%. The increased full width at half maximum of the Raman spectrum corroborates the decrease in lattice thermal conductivity. As a result, a maximum zT of 0.94 at 300 K and an average zT of 1.17 at 300–400 K were achieved in magnetic Mg₃(Sb,Bi)₂-based alloys. This work demonstrates a robust magnetism-induced diffuse scattering effect in improving the room-temperature thermoelectric performance.