Thermodynamic criterions of the thermoelectric performance enhancement in Mg2Sn through the self-compensation vacancy

• Published in: Materials today physics Vol. 16; p. 100327
• Main Authors: Zhu, Yongbin, Han, Zhijia, Jiang, Feng, Dong, Erting, Zhang, Bo-Ping, Zhang, Wenqing, Liu, Weishu
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2021
• Subjects: Alloying scattering; Mg2Sn; Self-compensation vacancy; Thermodynamic criterions; Thermoelectric; Self-compensation vacancy; Thermodynamic criterions; Thermoelectric; Alloying scattering; Mg2Sn
• ISSN: 2542-5293; 2542-5293
• DOI: 10.1016/j.mtphys.2020.100327

We show a significant increase in thermoelectric figure-of-merit ZTmax from 0.7 of the normally doped Mg2Sn0.99Sb0.01 to 1.2 of the self-compensatively doped Mg1.94Sn0.8Sb0.2, which corresponds to a 70% enhancement. We provide a thermodynamic equilibrium energy criterion that explains the formation of compensation defects, and non-equilibrium transport criterion that is relative to the self-compensation defects to boost the thermoelectric performance, i.e. the normalized change of material parameter ΔB/Bpure. Based on the theoretical basis of alloying scattering related to the electrons and phonons, we discuss the analytical optimized fraction of the dopants or the self-compensation vacancy in two cases, respectively. Our work provides a new theoretical guideline for the design of novel thermoelectric materials through the defects engineering, especially the self-compensation defects. [Display omitted] •The self-compensation Mg-vacancy has been induced by Sb doping in Mg2(1-y)Sn1-xSbx.•A thermodynamic equilibrium energy criterion explains the formation of compensation defects.•Analytical solution xopt=max{x0,12−1−4A2} of the optimized doping content is obtained based on ΔBBpure=u/arctan(u)1+x(1−x)3π2υl2ρ8kBTN0(UΞ)2−1.•A ZTmax of 1.2 at 500 °C is obtained for Mg1.94Sn0.8Sb0.2