Isotropic Conduction Network and Defect Chemistry in Mg3+δ Sb2 -Based Layered Zintl Compounds with High Thermoelectric Performance.

Thermoelectric performance in the layered Zintl phase n-type Mg3+δ (Sb,Bi)2 is reported. Insertion of the excess Mg into the compounds is crucial for realizing n-type carrier transport with multivalley and isotropic character. An excellent ZT of 1.51 ± 0.06 at 716 K is achieved in the sintered polycrystals at the composition of Mg3.2 Sb1.5 Bi0.49 Te0.01 .