Bi₂O₂Se oxyselenides, characterized with intrinsically low lattice thermal conductivity and large Seebeck coefficient, are potential n-type thermoelectric material in the mediate temperature range. Given the low carrier concentration of ~10¹⁵ cm⁻³ at 300 K, the intrinsically low electrical conductivity actually hinders further enhancement of their thermoelectric performance. In this work, the isovalent Te-substitution of Se plays an effective role in narrowing the band gap, which notably increases the carrier concentration to ~10¹⁸ cm⁻³ at 300 K and the electron conduction activation energy has been lowered significantly from 0.33 to 0.14 eV. As a consequence, the power factor has been improved from 104 μW·K⁻²·m⁻¹ for pristine Bi₂O₂Se to 297 μW·K⁻²·m⁻¹ for Bi₂O₂Se_0.96Te_0.04 at 823 K. Meanwhile, the suppressed lattice thermal conductivity derives from the introduced point defects by heavier Te atoms. The gradually decreased phonon mean free path reflects the increasingly intense phonon scattering. Ultimately, the ZT value attains 0.28 for Bi₂O₂Se_0.96Te_0.04 at 823 K, an enhancement by a factor of ~2 as compared to that of pristine Bi₂O₂Se. This study has demonstrated that Te-substitution of Se could synergistically optimize the electrical and thermal properties thus effectively enhancing the thermoelectric performance of Bi₂O₂Se.

中文翻译：

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Te替代协同优化Bi2O2Se陶瓷的电和热传输性能

Bi ₂ O ₂ Se氧硒化物本质上具有较低的晶格热导率和较大的塞贝克系数，是中等温度范围内潜在的n型热电材料。考虑到在300 K时〜10 ¹⁵ cm ^-3的低载流子浓度，本质上较低的电导率实际上阻碍了其热电性能的进一步提高。在这项工作中，Se的等价Te取代在缩小带隙方面起着有效的作用，这将使载流子浓度显着增加到〜10 ¹⁸ cm ^-3。在300 K时，电子传导活化能已从0.33 eV显着降低至0.14 eV。因此，功率因数已经从^104μW·K改善^-2 ·^米-1为原始的Bi ₂ Ò ₂硒至^{297μW·K -2} ·^米-1为铋₂ ö ₂硒_0.96碲_0.04 823 K。同时，受抑制的晶格热导率是由较重的Te原子引入的点缺陷引起的。逐渐减小的声子平均自由程反映了越来越强的声子散射。最终，Bi ₂ O ₂ Se的ZT值达到0.28在823 K处为_0.96 Te _0.04，与原始Bi ₂ O ₂ Se相比提高了〜2倍。这项研究表明，Te的Se取代可以协同优化电学和热学性质，从而有效地提高Bi ₂ O ₂ Se的热电性能。