First-Principles Thermoelectric Study of SrMgSi and CaMgGe Zintl-Phase Compounds

• Published in: ACS applied energy materials Vol. 6; no. 15; pp. 8141 - 8148
• Main Authors: Yang, Jinfeng, Yang, Zhaoyu, Wang, Xiaonan, Chen, Yuxiang, Xu, Yongze, Zou, Bo, Yan, Yuli, Sun, Huarui
• Format: Journal Article
• Language: English
• Published: American Chemical Society 14.08.2023
• Subjects: lattice thermal conductivity; first-principles calculations; thermoelectric; weak bonding; Zintl phases
• ISSN: 2574-0962; 2574-0962
• DOI: 10.1021/acsaem.3c01260

Zintl-phase semiconductor materials with low intrinsic lattice thermal conductivity have been the target of study for thermoelectric (TE) applications. Herein, we report Zintl-phase TiNiSi-type SrMgSi and CaMgGe with calculated low intrinsic lattice thermal conductivity (κL) values of 2.52 and 1.90 W/m·K at room temperature, respectively. The low κL is mainly due to the strong lattice anharmonicity, which originates from the weak bonding of cations in the anionic network, and strong optical-acoustic phonon coupling. Additionally, the high band degeneracy results in good electrical properties, and excellent ZT values of ∼2.83 (n-type, 500 K) and 3.09 (n-type, 500 K) are predicted for SrMgSi and CaMgGe, respectively. The theoretical study provides a valuable direction for exploring Zintl-phase materials for efficient TE power conversion.