Enhanced Thermoelectric Performance in N‐Type Mg_3.2Sb_1.5Bi_0.5 by La or Ce Doping into Mg

Abstract

Abstract N‐type Mg 3.2 Sb 1.5 Bi 0.5 materials are prepared by cation‐site doping with lanthanides (La, Ce). Both La‐ and Ce‐doped samples exhibit a higher doping limit and greater efficiency than those of chalcogen (Te, Se, S)‐doped n‐type Mg 3.2 Sb 1.5 Bi 0.5 samples. High electron carrier concentration ≈9 × 10 19 cm −3 is obtained in Mg 3.18 La 0.02 Sb 1.5 Bi 0.5 and Mg 3.185 Ce 0.015 Sb 1.5 Bi 0.5 , which is close to the theoretical doping‐concentration limit and induces contributions from more electron bands. A higher electrical conductivity was thus obtained and is beneficial to the enhanced ZT values for lanthanide‐doped Mg 3.2 Sb 1.5 Bi 0.5 . The highest ZT value ≈1.6 is achieved in Mg 3.19 La 0.01 Sb 1.5 Bi 0.5 at 693 K, along with a ZT ≈1.50 in Mg 3.19 Ce 0.01 Sb 1.5 Bi 0.5 at 693 K, indicating that lanthanides provide a promising doping strategy for Mg 3.2 Sb 1.5 Bi 0.5 ‐based materials.