Bi-Deficiency Leading to High-Performance in Mg<sub>3</sub> (Sb,Bi)<sub>2</sub> -Based Thermoelectric Materials.
basic_science · Level V
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- Record sourced from PubMed, PMID 36929018.
- Also identified by DOI 10.1002/adma.202209119.
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Abstract
Mg<sub>3</sub> (Sb,Bi)<sub>2</sub> 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 (V<sub>Mg</sub> ) in Mg<sub>3</sub> (Sb,Bi)<sub>2</sub> . This study proposes an approach to mitigating the negative scattering effect of V<sub>Mg</sub> by Bi deficiency, synergistically modulating the electrical and thermal transport properties to enhance the thermoelectric performance. Positron annihilation spectrometry and C<sub>s</sub> -corrected scanning transmission electron microscopy analyses indicated that the V<sub>Mg</sub> tends to coalesce due to the introduced Bi vacancies (V<sub>Bi</sub> ). The defects created by Bi deficiency effectively weaken the scattering of electrons from the intrinsic V<sub>Mg</sub> 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 Mg<sub>3</sub> (Sb,Bi)<sub>2</sub> by tuning the defect combination. This work demonstrates a feasible and effective approach to improving the performance of Mg<sub>3</sub> (Sb,Bi)<sub>2</sub> as an emerging thermoelectric material.