The thermoelectric properties of p-type SmMg₂Sb₂ are investigated by using the density functional theory and the Boltzmann transport equation method. It is found that SmMg₂Sb₂ shows a narrow band gap characteristic, and the crystal field splitting and spin-orbital coupling effect result in a singly degenerate valence band maximum. Meanwhile, SmMg₂Sb₂ exhibits an intrinsic low lattice thermal conductivity owing to the obvious phonon softening in the low-frequency acoustic branches. Based on a careful analysis of the band structure, we propose a scheme of metallic dopant at Sm site to promote the valence band convergence and improve the Seebeck coefficient. The improved thermoelectric properties are numerically confirmed in the Ba-doped p-type SmMg₂Sb₂, where a significantly improved ZT of 1.6 at 750 K is predicted with the synergistical effects of band engineering and enhanced phonon scattering.

采用密度泛函理论和玻尔兹曼输运方程法研究了p型SmMg ₂ Sb ₂的热电性质。发现SmMg ₂ Sb ₂具有窄带隙特性，晶体场分裂和自旋轨道耦合效应导致价带单简并最大值。同时，SmMg ₂ Sb ₂由于低频声学分支中明显的声子软化，表现出固有的低晶格热导率。在仔细分析能带结构的基础上，我们提出了一种在 Sm 位点添加金属掺杂剂的方案，以促进价带收敛并提高塞贝克系数。改进的热电特性在 Ba 掺杂的p型 SmMg ₂ Sb ₂中得到了数值证实，其中预计在 750 K 时ZT显着提高为 1.6，这与能带工程和增强的声子散射的协同效应相得益彰。