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| Main Authors: | , , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2511.15027 |
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| _version_ | 1866908664935219200 |
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| author | Deng, Zunyi Xuan, Wenwen Wei, Bin Li, Yongheng |
| author_facet | Deng, Zunyi Xuan, Wenwen Wei, Bin Li, Yongheng |
| contents | Bi2O2Se is an emerging semiconductor with intrinsically low thermal conductivity, making it a promising material for thermoelectric applications. Hydrostatic pressure can effectively tunes the thermal conductivity, with various pressure-dependent trends reported. However, its impact on thermal anisotropy, particularly in the highly anisotropic Bi2O2Se, remains poorly understood. Here, we report a pressure-driven reversal of thermal anisotropy: k_z < k_x at 0 GPa transforms into k_z > k_x at 60 GPa without phase transition. This stems from distinct phonon dispersions along the x- and z-directions under pressure, leading to a reshaped group velocity landscape. Below 10 meV, vz > vx at both pressures, with a much greater advantage at 60 GPa. Above 10 meV, vx > vz at 0 GPa; however, the difference nearly vanishes at 60 GPa. These changes result from anisotropic lattice compression, with the z-axis shrinking more significantly than the x-axis and suppressing the lone pair activity of Bi atoms. This study calls for revisiting the pressure dependence of thermal conductivity anisotropy and provides insights for pressure-driven thermal switching applications. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2511_15027 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Pressure-Induced Reversal of Thermal Anisotropy in Bi2O2Se Deng, Zunyi Xuan, Wenwen Wei, Bin Li, Yongheng Materials Science Applied Physics Bi2O2Se is an emerging semiconductor with intrinsically low thermal conductivity, making it a promising material for thermoelectric applications. Hydrostatic pressure can effectively tunes the thermal conductivity, with various pressure-dependent trends reported. However, its impact on thermal anisotropy, particularly in the highly anisotropic Bi2O2Se, remains poorly understood. Here, we report a pressure-driven reversal of thermal anisotropy: k_z < k_x at 0 GPa transforms into k_z > k_x at 60 GPa without phase transition. This stems from distinct phonon dispersions along the x- and z-directions under pressure, leading to a reshaped group velocity landscape. Below 10 meV, vz > vx at both pressures, with a much greater advantage at 60 GPa. Above 10 meV, vx > vz at 0 GPa; however, the difference nearly vanishes at 60 GPa. These changes result from anisotropic lattice compression, with the z-axis shrinking more significantly than the x-axis and suppressing the lone pair activity of Bi atoms. This study calls for revisiting the pressure dependence of thermal conductivity anisotropy and provides insights for pressure-driven thermal switching applications. |
| title | Pressure-Induced Reversal of Thermal Anisotropy in Bi2O2Se |
| topic | Materials Science Applied Physics |
| url | https://arxiv.org/abs/2511.15027 |