Enhancing the Thermoelectric Performance of p-Type MgSb via Codoping of Li and Cd.

The Zintl compound MgSb is a promising thermoelectric material with Earth-abundant components. Compared to its n-type counterpart, p-type MgSb reveals lower dimensionless figure of merit (), principally due to the inferior electronic properties. Herein, p-type MgSb materials codoped with Li and Cd have been synthesized via a ball milling plus hot pressing method, and their thermoelectric properties are systematically investigated within the temperature range 300-773 K. Li is found to be an effective hole dopant, which leads to a of 0.46 at 773 K in MgLiSb that doubles the of MgSb. Additional Cd doping further increases carrier mobility ascribed to the weakened polar covalent bonding and diminishes the lattice thermal conductivity simultaneously due to the introduced atomic mass contrast between Cd and Mg. Eventually, the optimized power factor combined with the reduced thermal conductivity has significantly improved the thermoelectric performance of p-type MgSb, with MgLiCdSb achieving a maximum of ∼0.68 at 773 K and an average of ∼0.32 over 300-773 K that compare very favorably to those of pristine MgSb. This study demonstrates that (Li, Cd) codoping is an effective strategy to enhance the thermoelectric properties of p-type MgSb materials.