Defect-Energy-Targeted Lattice Repair Delivers High Thermoelectric Performance in Magnesium Antimonide

作者：J. S. Jiang, Minhui Yuan, Yuntian Fu, Yanqi Huang, W. F. Li, Jingyi Lyu, Zeqing Hu, Shenghua Liu, Ran He, Yanglong Hou, Jing Shuai · 发表于：Journal of the American Chemical Society · 年份：2026 · DOI：10.1021/jacs.6c02279 · 被引用次数：3 · 研究领域：Advanced Thermoelectric Materials and Devices、Thermal Expansion and Ionic Conductivity、Heusler alloys: electronic and magnetic properties

High Resolution Image Download MS PowerPoint Slide Magnesium-based Mg 3 (Sb,Bi) 2 has emerged as a premier candidate for waste-heat recovery. However, its performance is fundamentally capped by intrinsic Mg vacancies that severely scatter carriers. Here, we overcome this bottleneck via a defect-energy-targeted lattice repair strategy, substituting labile Mg sites with homologous alkaline-earth metals (Ca, Sr, Ba). Theoretical calculations reveal that the lower electronegativity of these dopants strengthens the local metal–Sb bonding, drastically raising the vacancy formation energy from ∼0.97 to ∼2.42 eV. This thermodynamic stabilization effectively “repairs” the lattice, suppressing vacancy generation and yielding a ∼35% boost in carrier mobility without compromising carrier concentration. Simultaneously, the heavy dopants induce mass fluctuations and strain fields that, coupled with dense dislocations, minimize the lattice thermal conductivity to ∼0.4 W m –1 K –1 at 773 K. The synergy of restored charge transport and suppressed heat propagation leads to a record-high figure of merit ( zT ) of ∼2.1 at 773 K and an outstanding average zT of ∼1.5 in Mg 3.2 Ba 0.005 Sb 1.5 Bi 0.49 Te 0.01 . Remarkably, a single-leg device demonstrates a conversion efficiency of ∼14%, outperforming state-of-the-art n-type thermoelectrics. This work demonstrates that targeting defect energetics is a powerful, broadly applicable approach to breaking the performance ceilings of Zintl-phase thermoel...