Enhancing the Thermoelectric Performance of p-Type Mg 3 Sb 2 via Codoping of Li and Cd

作者：Xiaodan Tang, Bin Zhang, Xiao Zhang, Shuxiao Wang, Xu Lu, Guang Han, Guoyu Wang, Xiaoyuan Zhou · 发表于：ACS Applied Materials & Interfaces · 年份：2020 · DOI：10.1021/acsami.9b23059 · 被引用次数：86 · 研究领域：Advanced Thermoelectric Materials and Devices、Thermal properties of materials、Thermal Radiation and Cooling Technologies

The Zintl compound Mg 3 Sb 2 is a promising thermoelectric material with Earth-abundant components. Compared to its n-type counterpart, p-type Mg 3 Sb 2 reveals lower dimensionless figure of merit ( zT ), principally due to the inferior electronic properties. Herein, p-type Mg 3 Sb 2 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 zT of 0.46 at 773 K in Mg 2.99 Li 0.01 Sb 2 that doubles the zT of Mg 3 Sb 2 . 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 Mg 3 Sb 2, with Mg 2.69 Li 0.01 Cd 0.5 Sb 2 achieving a maximum zT of ∼0.68 at 773 K and an average zT ave of ∼0.32 over 300–773 K that compare very favorably to those of pristine Mg 3 Sb 2 . This study demonstrates that (Li, Cd) codoping is an effective strategy to enhance the thermoelectric properties of p-type Mg 3 Sb 2 materials.