(GeTe)nBi2Te3的结构与热电性能研究

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%。

Structures and Thermoelectric Properties of(GeTe)nBi2Te3

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.