Abstract
Full-Heusler thermoelectric materials have intrinsically low lattice thermal conductivity. Our first-principles calculations show that Ba2AgSb is a semiconductor with an indirect band gap of 0.49 eV. The electronic band degeneracy and pockets near the Fermi level facilitate electron transport. The short phonon relaxation time, small group velocity (1.89 km s-1), and large phonon scattering space reflect the intense phonon-phonon scattering. The large Grüneisen parameter (1.44) accounts for the strong phonon anharmonicity, thus the low lattice thermal conductivity of 0.5Wm-1K-1 at 800 K. The isotropic figure of merit with a maximum value of 4.7 at 750 K is comparable to that of reported materials. The distribution of phonon momentum uncovers the important role of Ag in resisting thermal transport. The analysis of symmetry-based phonon-phonon scattering routes reveals the significance of symmetry on phonon scattering. The crystal structure of Ba2AgSb can be used to regulate chemical elements to build high-performance thermoelectric materials. Our calculations provide an effective way to design thermoelectric materials, stimulating the study of full-Heusler materials.
Original language | English |
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Article number | 034023 |
Journal | Physical Review Applied |
Volume | 17 |
Issue number | 3 |
DOIs | |
State | Published - Mar 2022 |
Externally published | Yes |
Funding
The calculations were performed at the Supercomputer Centre in the China Spallation Neutron Source, and we thank the workers in the Supercomputer Centre. This work is supported by the Science Center of the National Natural Science Foundation of China (Grant No. 52088101), the National Natural Science Foundation of China (Grants No. 11675195, No. U1932220, and No. 12074381), the National Key R&D Program of China (Grant No. 2017YFA0403700), the Key Research Program of Frontier Sciences, CAS (Grant No. 292016YQYKXJ00135), and the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2019A1515111025).