Probing Efficient N‐Type Lanthanide Dopants for Mg(3)Sb(2) Thermoelectrics

The recent discovery of n‐type Mg(3)Sb(2) thermoelectrics has ignited intensive research activities on searching for potential n‐type dopants for this material. Using first‐principles defect calculations, here, a systematic computational screening of potential efficient n‐type lanthanide dopants is conducted for Mg(3)Sb(2). In addition to La, Ce, Pr, and Tm, it is found that high electron concentration (≳10(20) cm(−3) at the growth temperature of 900 K) can be achieved by doping on the Mg sites with Nd, Gd, Ho, and Lu, which are generally more efficient than other lanthanide dopants and the anion‐site dopant Te. Experimentally, Nd and Tm are confirmed as effective n‐type dopants for Mg(3)Sb(2) since doping with Nd and Tm shows higher electron concentration and thermoelectric figure of merit zT than doping with Te. Through codoping with Nd (Tm) and Te, simultaneous power factor improvement and thermal conductivity reduction are achieved. As a result, high zT values of ≈1.65 and ≈1.75 at 775 K are obtained in n‐type Mg(3.5)Nd(0.04)Sb(1.97)Te(0.03) and Mg(3.5)Tm(0.03)Sb(1.97)Te(0.03), respectively, which are among the highest values for n‐type Mg(3)Sb(2) without alloying with Mg(3)Bi(2). This work sheds light on exploring promising n‐type dopants for the design of Mg(3)Sb(2) thermoelectrics.