Benefiting from the unique “Phonon-Glass, Electron-Crystal” (PGEC) characteristic, Zintl phases have been considered as a kind of promising thermoelectric materials. For the typical AM₂X₂ compounds with the CaAl₂Si₂-type structure, YbMg₂Bi₂ has shown competitive thermoelectric performance recently. Nevertheless, the optimization of YbMg₂Bi₂ compounds is primarily focused on the substitution on Yb or Mg site. Herein, the Bi site is substituted by isoelectric Sb and the effect on the thermoelectric transport behavior is investigated. The partial substitution reduces the carrier concentration and induces the lattice deformation caused by the different atomic radius and mass between Bi and Sb, further leading to the decreased power factor and thermal conductivity. Fortunately, the reduction extent of the thermal conductivity outperforms that of power factor. Finally, the Sb substitution successfully results in a better thermoelectric performance compared with that of the pristine YbMg₂Bi_1.98. Especially, the calculated energy conversion efficiency (η) of YbMg₂Bi_1.88Sb_0.1 which also possesses a relatively high output power density reaches the maximum value of 9.8 % when T_h = 873 K, and T_c = 300 K, respectively. This work demonstrates that the idea of substitution on anionic site should be a new strategy to achieve better ZT values for AM₂X₂ compounds.

得益于独特的“ Phonon玻璃，电子晶体”（PGEC）特性，Zintl相被认为是一种很有前途的热电材料。对于具有CaAl ₂ Si ₂型结构的典型AM ₂ X ₂化合物，YbMg ₂ Bi ₂最近显示出有竞争力的热电性能。尽管如此，YbMg ₂ Bi ₂的优化化合物主要集中在Yb或Mg位置的取代。在此，Bi位点被等电Sb取代，并研究了其对热电传输行为的影响。部分取代降低了载流子浓度，并引起了Bi和Sb之间不同的原子半径和质量所引起的晶格变形，进而导致功率因数和导热系数降低。幸运的是，热导率的降低程度优于功率因数。最后，与原始YbMg ₂ Bi _1.98相比，Sb取代成功地产生了更好的热电性能。特别地，计算出的YbMg ₂ Bi的能量转换效率（η）当T _h = 873 K和T _c = 300 K时，同样具有较高输出功率密度的_1.88 Sb _0.1达到最大值9.8％。这项工作表明，在阴离子位点上进行取代的想法应成为一种新的策略，以实现对A M ₂ X ₂化合物更好的ZT值。