Bismuth tellurohalides with Rashba-type spin splitting exhibit unique Fermi surface topology and are developed as promising thermoelectric materials. However, BiTeBr, which belongs to this class of materials, is rarely investigated in terms of the thermoelectric transport properties. In the study, polycrystalline bulk BiTeBr with intensive texture was synthesized via spark plasma sintering (SPS). Additionally, its thermoelectric properties above room temperature were investigated along both the in-plane and out-plane directions, and they exhibit strong anisotropy. Low sound velocity along two directions is found and contributes to its low lattice thermal conductivity. Polycrystalline BiTeBr exhibits relatively good thermoelectric performance along the in-plane direction, with a maximum dimensionless figure of merit (ZT) of 0.35 at 560 K. Further enhancements of ZT are expected by utilizing systematic optimization strategies.

中文翻译：

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密集织构Rashba半导体BiTeBr的合成及热电性能

具有Rashba型自旋分裂的碲卤化铋表现出独特的费米表面拓扑结构，被开发为有前途的热电材料。然而，属于此类材料的 BiTeBr 在热电传输性能方面却很少被研究。在这项研究中，通过放电等离子烧结（SPS）合成了具有密集织构的多晶块状 BiTeBr。此外，沿着面内和面外方向研究了其高于室温的热电性能，它们表现出很强的各向异性。沿着两个方向的低声速被发现并有助于其低晶格热导率。多晶 BiTeBr 沿面内方向表现出相对良好的热电性能，在 560 K 时最大无量纲品质因数 (ZT) 为 0.35。通过利用系统优化策略，预计 ZT 会进一步增强。