n-type Mg₃Sb₂-based materials have become a top candidate for efficient thermoelectric applications within 300–700 K, due to its high band degeneracy, inherently high carrier mobility and low lattice thermal conductivity, as well as its advantages of less toxicity and abundance. Existing works showed that Mg₃Bi₂-alloying largely help ensure the exceptional performance, leaving a key issue to be uncovered on the primary mechanisms favoring or limiting the thermoelectric performance of Mg₃Sb_2-xBi_x alloys. Here we focus on the alloy composition dependent transport properties at various temperatures, with a large volume of experimental data. It is revealed that, with increasing x, the reduction in both inertial mass and lattice thermal conductivity is significantly beneficial, but the closure in band gap leads to a strong compensation due to the bipolar effect. Such a compromise between band structure and phonon scattering results in optimal Mg₃Bi₂-alloying concentrations to be about 50%–75% at 300 K, 50%–60% at 450 K and 50% at 600 K, which successfully guiding this work to realize extraordinary thermoelectric figure of merit at these temperatures.

基于n型Mg ₃ Sb ₂的材料由于其高频带简并性，固有的高载流子迁移率和低晶格热导率以及低毒性的优点，已成为300-700 K范围内高效热电应用的最佳候选材料。和丰富。现有工作表明，Mg ₃ Bi ₂合金在很大程度上有助于确保优异的性能，而在有利于或限制Mg ₃ Sb _{2- x} Bi _x的热电性能的主要机理上仍未发现关键问题。合金。在这里，我们着重于在各种温度下依赖于合金成分的传输性能，并具有大量实验数据。结果表明，随着x的增加，惯性质量和晶格热导率的降低都是非常有益的，但是由于双极效应，带隙的闭合导致了很强的补偿。能带结构和声子散射之间的这种折衷导致最佳的Mg ₃ Bi ₂合金浓度在300 K时约为50％–75％，在450 K时约为50％–60％，在600 K时为50％，这成功地指导了这一点。在这些温度下努力实现非凡的热电品质因数。