Tang Xiaodan, Zhang Bin, Zhang Xiao, Wang Shuxia, Lu Xu, Han Guang, Wang Guoyu, Zhou Xiaoyuan
Chongqing Key Laboratory of Soft Condensed Matter Physics and Smart Materials, College of Physics , Chongqing University , Chongqing 401331 , P. R. China.
Analytical and Testing Center , Chongqing University , Chongqing 401331 , P. R. China.
ACS Appl Mater Interfaces. 2020 Feb 19;12(7):8359-8365. doi: 10.1021/acsami.9b23059. Epub 2020 Feb 10.
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.
津特耳化合物MgSb是一种很有前景的热电材料，其组成元素在地壳中储量丰富。与n型MgSb相比，p型MgSb的无量纲品质因数（）较低，主要原因是其电子性能较差。在此，通过球磨加热压法合成了共掺杂Li和Cd的p型MgSb材料，并在300 - 773 K的温度范围内系统研究了它们的热电性能。发现Li是一种有效的空穴掺杂剂，在MgLiSb中，773 K时的达到0.46，是MgSb的两倍。额外的Cd掺杂由于减弱了极性共价键而进一步提高了载流子迁移率，同时由于Cd和Mg之间引入的原子质量差异而降低了晶格热导率。最终，优化的功率因数与降低的热导率相结合，显著提高了p型MgSb的热电性能，MgLiCdSb在773 K时的最大值约为0.68，在300 - 773 K范围内的平均值约为0.32，与原始MgSb相比具有很大优势。这项研究表明，（Li，Cd）共掺杂是提高p型MgSb材料热电性能的有效策略。
