Significant first-principles electron-phonon coupling effects in the LiZnAs and ScAgC half-Heusler thermoelectrics
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arXiv
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| Format: | Preprint |
| Publié: |
2025
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| _version_ | 1866911565948649472 |
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| author | Solet, Vinod Kumar Pandey, Sudhir K. |
| author_facet | Solet, Vinod Kumar Pandey, Sudhir K. |
| contents | The half-Heusler (hH) compounds are currently considered promising thermoelectric (TE) materials due to their favorable thermopower and electrical conductivity. Accurate estimates of these properties are therefore highly desirable and require a detailed understanding of the microscopic mechanisms that govern transport. To enable such estimations, we carry out comprehensive first-principles computations of one of the primary factors limiting carrier transport, namely the electron-phonon ($e-ph$) interaction, in LiZnAs and ScAgC. Our study first investigates their electron and phonon dispersions and then examines the temperature-induced renormalization of the electronic states. We then solve the Boltzmann transport equation (BTE) under multiple relaxation-time approximations (RTAs) to evaluate the carrier transport properties. Phonon-limited electron and hole mobilities are comparatively assessed using the linearized self-energy and momentum RTAs (SERTA and MRTA), and the exact or iterative BTE (IBTE) solutions within $e-ph$ coupling. Electrical transport coefficients for TE performance are also comparatively analyzed under the constant RTA (CRTA), SERTA, and MRTA schemes. The lattice thermal conductivity, determined from phonon-phonon interaction, is further reduced through nanostructuring techniques. The bulk LiZnAs (ScAgC) compound achieves the highest figure of merit ($zT$) of 1.05 (0.78) at 900 K with an electron doping concentration of 10$^{18}$ (10$^{19}$) cm$^{-3}$ under the MRTA scheme. This value significantly increases to 1.53 (1.0) for a 20 nm nanostructured sample. The remarkably high $zT$ achieved through inherently present phonon-induced electron scattering effects, combined with grain-boundary engineering, opens a promising path for discovering highly efficient and accurate next-generation hH TEs. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_13675 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Significant first-principles electron-phonon coupling effects in the LiZnAs and ScAgC half-Heusler thermoelectrics Solet, Vinod Kumar Pandey, Sudhir K. Materials Science Mesoscale and Nanoscale Physics Other Condensed Matter Strongly Correlated Electrons Applied Physics The half-Heusler (hH) compounds are currently considered promising thermoelectric (TE) materials due to their favorable thermopower and electrical conductivity. Accurate estimates of these properties are therefore highly desirable and require a detailed understanding of the microscopic mechanisms that govern transport. To enable such estimations, we carry out comprehensive first-principles computations of one of the primary factors limiting carrier transport, namely the electron-phonon ($e-ph$) interaction, in LiZnAs and ScAgC. Our study first investigates their electron and phonon dispersions and then examines the temperature-induced renormalization of the electronic states. We then solve the Boltzmann transport equation (BTE) under multiple relaxation-time approximations (RTAs) to evaluate the carrier transport properties. Phonon-limited electron and hole mobilities are comparatively assessed using the linearized self-energy and momentum RTAs (SERTA and MRTA), and the exact or iterative BTE (IBTE) solutions within $e-ph$ coupling. Electrical transport coefficients for TE performance are also comparatively analyzed under the constant RTA (CRTA), SERTA, and MRTA schemes. The lattice thermal conductivity, determined from phonon-phonon interaction, is further reduced through nanostructuring techniques. The bulk LiZnAs (ScAgC) compound achieves the highest figure of merit ($zT$) of 1.05 (0.78) at 900 K with an electron doping concentration of 10$^{18}$ (10$^{19}$) cm$^{-3}$ under the MRTA scheme. This value significantly increases to 1.53 (1.0) for a 20 nm nanostructured sample. The remarkably high $zT$ achieved through inherently present phonon-induced electron scattering effects, combined with grain-boundary engineering, opens a promising path for discovering highly efficient and accurate next-generation hH TEs. |
| title | Significant first-principles electron-phonon coupling effects in the LiZnAs and ScAgC half-Heusler thermoelectrics |
| topic | Materials Science Mesoscale and Nanoscale Physics Other Condensed Matter Strongly Correlated Electrons Applied Physics |
| url | https://arxiv.org/abs/2506.13675 |