Thermoelectric properties enhanced by band engineering and acoustic-optical branch crossover avoidance.
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| Title: | Thermoelectric properties enhanced by band engineering and acoustic-optical branch crossover avoidance. |
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| Authors: | Zhang, Aojie1 (AUTHOR), Wu, Chao1 (AUTHOR), Guo, Mingxing1 (AUTHOR), Zhang, Qiang2 (AUTHOR), Fan, Wenhao3 (AUTHOR) fanwenhao@tyut.edu.cn, Chen, Shaoping1 (AUTHOR) sxchenshaoping@163.com |
| Source: | Journal of Materials Science. May2025, Vol. 60 Issue 20, p8464-8476. 13p. |
| Subjects: | Conduction bands, Thermal conductivity, Carrier density, Band gaps, Group velocity, Thermoelectric materials |
| Abstract: | Mg3Sb2-based thermoelectric materials have attracted considerable attention due to their non- toxicity, ease of fabrication, and outstanding performance in medium-to-low temperature ranges, yet a critical challenge remains in further enhancing electrical properties while effectively suppressing thermal conductivity. This study employs a Y-doping strategy combined with first-principles calculations to reveal the optimization mechanisms: Y incorporation shifts the Fermi level toward the conduction band, enabling n-type conductivity with a maximum carrier concentration of 1.26 × 1020 cm−3 and concurrently reducing the band gap to achieve a power factor of 14.82 μW cm−1 K−2; the substantial mass disparity between Y and Mg induces mass-field fluctuations, triggering an avoided crossing phenomenon in the phonon spectrum that weakens acoustic-optical phonon branch interactions and significantly reduces phonon group velocity, thereby suppressing lattice thermal conductivity. Ultimately, the thermoelectric figure of merit reaches 1.056 at 725 K. Crystal orbital Hamilton population (COHP) analysis further demonstrates strengthened Y–Mg bonding, which enhances structural stability. This work provides insights into dopant-mediated thermoelectric performance optimization through the coupling of electronic transport enhancement and phonon engineering. By doping foreign elements, the Fermi level shifts from the valence band to the conduction band, thereby optimizing carrier concentration, as shown in Figs. (a) and (b). In addition, introducing mass differences between dopant atoms and matrix atoms drives the avoidance of crossover behavior between the acoustic and optical branches, as shown in Figs. (c) and (d). This phenomenon reduces phonon group velocity, as shown in Figs. (d) and (e), thereby suppressing lattice thermal conductivity and enhancing thermoelectric performance. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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| Abstract: | Mg3Sb2-based thermoelectric materials have attracted considerable attention due to their non- toxicity, ease of fabrication, and outstanding performance in medium-to-low temperature ranges, yet a critical challenge remains in further enhancing electrical properties while effectively suppressing thermal conductivity. This study employs a Y-doping strategy combined with first-principles calculations to reveal the optimization mechanisms: Y incorporation shifts the Fermi level toward the conduction band, enabling n-type conductivity with a maximum carrier concentration of 1.26 × 1020 cm−3 and concurrently reducing the band gap to achieve a power factor of 14.82 μW cm−1 K−2; the substantial mass disparity between Y and Mg induces mass-field fluctuations, triggering an avoided crossing phenomenon in the phonon spectrum that weakens acoustic-optical phonon branch interactions and significantly reduces phonon group velocity, thereby suppressing lattice thermal conductivity. Ultimately, the thermoelectric figure of merit reaches 1.056 at 725 K. Crystal orbital Hamilton population (COHP) analysis further demonstrates strengthened Y–Mg bonding, which enhances structural stability. This work provides insights into dopant-mediated thermoelectric performance optimization through the coupling of electronic transport enhancement and phonon engineering. By doping foreign elements, the Fermi level shifts from the valence band to the conduction band, thereby optimizing carrier concentration, as shown in Figs. (a) and (b). In addition, introducing mass differences between dopant atoms and matrix atoms drives the avoidance of crossover behavior between the acoustic and optical branches, as shown in Figs. (c) and (d). This phenomenon reduces phonon group velocity, as shown in Figs. (d) and (e), thereby suppressing lattice thermal conductivity and enhancing thermoelectric performance. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 00222461 |
| DOI: | 10.1007/s10853-025-10926-2 |
