在GeTe-Bi₂Te₃赝二元系统中, (GeTe)_n(Bi₂Te₃)_m化合物往往具有较低的晶格热导率, 但其中很多组分的热电性能尚未得到系统研究。本研究通过熔融、淬火、退火结合放电等离子烧结工艺制备了一系列(GeTe)_nBi₂Te₃(n=10, 11, 12, 13, 14)单相多晶样品, 并对其相组成和热电性能进行表征和研究。掺杂Bi₂Te₃可以显著增强点缺陷声子散射, 大幅度降低材料的晶格热导率, 在723 K时, (GeTe)₁₃Bi₂Te₃样品的总热导率低至1.63 W?m ^-1?K ^-1。此外, 掺杂Bi₂Te₃和调控GeTe的相对含量, 提高了材料的载流子有效质量, 即使在较高的载流子浓度下, 样品依然保持较高的塞贝克系数和功率因子, 在723 K, (GeTe)₁₃Bi₂Te₃样品获得最大的功率因子为2.88×10 ^-3 W?m ^-1?K ^-2, 最终(GeTe)₁₃Bi₂Te₃样品在723 K获得的最大ZT值达到1.27, 较未掺杂的GeTe样品提高了16%。

In general, (GeTe)_n(Bi₂Te₃)_m compounds in GeTe-Bi₂Te₃ pseudo-binary system possess a relatively low thermal conductivity, however, the thermoelectric properties of these compounds have not been evaluated systematically. In this study, a series of single-phase (GeTe)_nBi₂Te₃ (n=10, 11, 12, 13, 14) compounds were prepared by a melting-quenching-annealing process combined with spark plasma sintering. The phase compositions and thermoelectrical properties of these samples were characterized. It is found that doping with Bi₂Te₃ intensifies the phonon scattering and significantly reduces the lattice thermal conductivities of these samples, producing a low total thermal conductivity of 1.63 W?m ^-1?K ^-1 at 723 K for (GeTe)₁₃Bi₂Te₃ compound. Moreover, the effective mass of these compounds is enhanced through adjustment of the relative amount of Bi₂Te₃ and GeTe. Therefore, the Seebeck coefficient and power factor of these samples remain superior even at high carrier concentration. At 723 K, the maximum power factor of (GeTe)₁₃Bi₂Te₃ compound is 2.88×10 ^-3 W?m ^-1?K ^-2 and the maximum ZT of (GeTe)₁₃Bi₂Te₃ is 1.27, which is 16% higher than that of pristine GeTe.