Ge1–xInxTe微观结构对热电性能的影响

Influence of GeInTe Microstructure on Thermoelectric Properties

在GeTe中掺杂In能够引入共振能级,但其微观结构对热电性能的影响还不明确。本研究采用熔炼–淬火–退火并结合放电等离子体烧结(SPS)的方法制备了系列Ge1–xInxTe样品,采用XRD、SEM、激光导热仪和热电性能分析系统(ZEM-3)对其微观结构和热电性能进行了研究。结果表明,随着In元素的掺入,Ge1–xInxTe的晶胞体积减小、人字鱼骨结构变小、晶界增多,导致晶格热导率降低,获得的最低热导率为2.16 W·m–1·K–1。同时,掺杂In引入了共振能级,降低了载流子浓度,使塞贝克系数以及功率因子增大。当In掺杂量x为0.03时, Ge1–xInxTe在600 K时获得最大ZT值1.15,比GeTe提升了26.4%,表明调整Ge1–xInxTe的微观结构可以有效提升热电性能。

The resonant levels can be introduced into GeTe by In element, however, the effect of its microstructure on thermoelectric properties still remained unclear. In this study, a series of Ge1–xInxTe samples were prepared by smelting-quenching-annealing combined with spark plasma sintering(SPS). The XRD, SEM, laser thermal conductivity instrument and thermoelectric performance analysis system(ZEM-3) were applied to study the microstructure and thermoelectric properties. Results show that, with the incorporation of In content, the unit cell volume decreases, and Herringbone structure has become smaller and grain boundaries increase, which result in a decrease in the lattice thermal conductivity. Thereby, a minimum thermal conductivity of 2.16 W·m–1·K–1 is obtained. Meanwhile, In doping introduces the resonant levels and decreases the carrier concentration, so the Seebeck coefficient and the power factor increase. Consequently, the maximum ZT value of 1.15 is obtained in the 0.03 sample at 600 K, which is 26.4% higher than that of GeTe. This indicates that the thermoelectric properties of Ge1–xInxTe can be effectively improved by the microstructure regulation.