Bi‐Deficiency Leading to High‐Performance in Mg₃(Sb,Bi)₂‐Based Thermoelectric Materials

Abstract

Mg3(Sb,Bi)2 is a potential nearly‐room temperature thermoelectric compound composed of earth‐abundant elements. However, complex defect tuning and exceptional microstructural control are required. Prior studies have confirmed the detrimental effect of Mg vacancies (VMg) in Mg3(Sb,Bi)2. This study proposes an approach to mitigating the negative scattering effect of VMg by Bi deficiency, synergistically modulating the electrical and thermal transport properties to enhance the thermoelectric performance. Positron annihilation spectrometry and Cs‐corrected scanning transmission electron microscopy analyses indicated that the VMg tends to coalesce due to the introduced Bi vacancies (VBi). The defects created by Bi deficiency effectively weaken the scattering of electrons from the intrinsic VMg and enhance phonon scattering. A peak zT of 1.82 at 773 K and high conversion efficiency of 11.3% at ∆T = 473 K are achieved in the optimized composition of Mg3(Sb,Bi)2 by tuning the defect combination. This work demonstrates a feasible and effective approach to improving the performance of Mg3(Sb,Bi)2 as an emerging thermoelectric material.

High Thermoelectric Performance in Rhombohedral GeSe-LiBiTe2

“…Various promising material systems have recently emerged for thermoelectric applications, including Mg 3 Sb 2 , 9,10 GeTe, 11,12 MgAgSb, 13 and SnSe. 14−16 In particular, SnSe, characterized by a layered structure, exhibits fascinating electrical transport properties owing to its complex band geometry.…”

“…Various promising material systems have recently emerged for thermoelectric applications, including Mg 3 Sb 2 , , GeTe, , MgAgSb, and SnSe. − In particular, SnSe, characterized by a layered structure, exhibits fascinating electrical transport properties owing to its complex band geometry . Moreover, it demonstrates ultralow thermal conductivity due to its strong anharmonicity. , Consequently, p-type and n-type SnSe with wide band gap have attained record-high ZT values over a wide temperature range, , making it suitable for thermoelectric generators .…”