Enhanced electrical transport performance through cation site doping in Y-doped Mg_(3.2)Sb_(2)

Mg_(3)Sb_(2)-based alloys are promising thermoelectric materials through n-type doping in Mg-rich growth conditions to overcome their intrinsic p-type behavior.First principle calculations are employed to investigate the dopant formation energy and electronic structures of Y-doped Mg_(3)Sb_(2).Results indicate that the Y atom is more favorable for substitution at the cation site.Simultaneously,the flattened band structure and increased density of state near the Fermi level of Y-doped Mg_(3)Sb_(2) indicate an enhanced electronic transport performance.The carrier concentration rises to 5.31×10^(19) cm^(-3) at room temperature,resulting in a significant increased power factor for Mg_(3.17)Y_(0.03)Sb_(2).The available optimization of electrical transport contributes to excellent thermoelectric performance,and a peak ZT~0.83 at 773 K was achieved for Y concentration x=0.03 in Mg_(3.2-x)Y_(x)Sb_(2).This work provides an alternative measure for optimizing the thermoelectric performance of n-type Mg_(3)Sb_(2) alloys by cation site doping.