Efficient thermoelectric devices are typically built from semiconducting materials since their band gap leads to an asymmetry in the continuum of energy-dependent charge transport necessary for a large Seebeck effect. Due to their low cost and excellent mechanical properties half- and full-Heusler compounds have emerged as promising candidates for various applications. Here, we demonstrate how the thermopower of semimetallic Fe₂VAl-based Heusler alloys can be significantly increased by transferring electronic states from within the pseudogap to higher energies. Density functional theory calculations predict that partial Ti and Si co-substitution in Fe₂V_1−xTi_xAl_1−ySi_y drives an opening of the pseudogap, that can be likewise achieved in Fe₂V_1−xTa_xAl_1−ySi_y. Consequently, our experimental measurements on these co-substituted systems reveal exceptionally large thermoelectric power factors (7.3 − 10.3 mWm⁻¹K⁻² near room temperature), as well as average power factors up to 4.6 mWm⁻¹K⁻² in the most pratical temperature range (293 − 573 K). With this work we set the course for a general and reliable way of boosting the thermoelectric performance of semimetallic Heusler alloys.

高效的热电器件通常由半导体材料制成，因为它们的带隙会导致大塞贝克效应所必需的能量相关电荷传输连续体中的不对称性。由于其低成本和优异的机械性能，半和全 Heusler 化合物已成为各种应用的有希望的候选者。在这里，我们展示了如何通过将电子态从赝能隙内转移到更高的能量来显着提高半金属 Fe ₂ VAL 基 Heusler 合金的热电势。密度泛函理论计算预测 Fe ₂ V _{1− x} Ti _x Al _{1− y} Si _{y中的部分 Ti 和 Si 共取代}驱动赝隙的打开，这同样可以在 Fe ₂ V _{1- x} Ta _x Al _{1- y} Si _y中实现。因此，我们对这些共同替代系统的实验测量结果显示出异常大的热电功率因数（接近室温时为7.3 - 10.3 mWm ^-1 K ^-2 ），平均功率因数最多可达 4.6 mWm ^-1 K ^-2实际温度范围（293 - 573 K）。通过这项工作，我们为提高半金属 Heusler 合金热电性能的通用可靠方法奠定了基础。