Low Electron Scattering Potentials in High Performance Mg2Si0.45Sn0.55 Based Thermoelectric Solid Solutions with Band Convergence

• Published in: Advanced energy materials 2013-09, Vol.3 (9), p.1238-1244
• Main Authors: Liu, Xiaohua, Zhu, Tiejun, Wang, Heng, Hu, Lipeng, Xie, Hanhui, Jiang, Guangyu, Snyder, G. Jeffrey, Zhao, Xinbing
• Format: Article
• Language: English
• Subjects: alloys; charge transport; Convergence; Microelectronics; semiconductor; Solid solutions; thermoelectrics
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.201300174

Understanding the electron and phonon transport characteristics is crucial for designing and developing high performance thermoelectric materials. Weak scattering effects on charge carriers, characterized by deformation potential and alloy scattering potential, are favorable for thermoelectric solid solutions to enable high carrier mobility and thereby promising thermoelectric performance. Mg2(Si,Sn) solid solutions have attracted much attention due to their low cost and environmental compatibility. Usually, their high thermoelectric performance with ZT ∼ 1 is ascribed to the band convergence and reduced lattice thermal conductivity caused by alloying. In this work, both a low deformation potential Ξ = 13 eV and a low alloy scattering potential U = 0.7 eV are found for the thermoelectric alloys by characterizing and modeling of thermoelectric transport properties. The band convergence is also verified by the increased density‐of‐states effective mass. It is proposed that, in addition to band convergence and reduced lattice thermal conductivity, the low deformation potential and alloy scattering potential are additional intrinsic features that contribute to the high thermoelectric performance of the solid solutions. Both the acoustic phonon scattering and alloy scattering contribute to the carrier transport in the Sb doped Mg2Si0.45Sn0.55 solid solutions. A low deformation potential and a low alloy scattering potential have been derived by modeling of thermoelectric transport properties, which are believed to be intrinsic features contributing to the high thermoelectric performance of the solid solutions.