1. Se-alloying reducing lattice thermal conductivity of Ge0.95Bi0.05Te
- Author
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Hao Wu, Zhigang Chen, Qingfeng Liu, Liang-Cao Yin, Xiaolei Shi, Yuewen Zhang, Han Gao, Yifeng Wang, Wei-Di Liu, Xueping Wu, and De-Zhuang Wang
- Subjects
Materials science ,Polymers and Plastics ,Phonon scattering ,Condensed matter physics ,Mechanical Engineering ,Metals and Alloys ,Pellets ,Thermoelectric materials ,Crystallographic defect ,Matrix (mathematics) ,Chemical bond ,Mechanics of Materials ,Thermoelectric effect ,Materials Chemistry ,Ceramics and Composites ,Figure of merit - Abstract
High lattice thermal conductivity of intrinsic GeTe limits the wide application of GeTe-based thermoelectrics. Recently, the optimization of GeTe-based thermoelectric materials has been focusing on reducing lattice thermal conductivity via strengthening phonon scattering. In this study, we systematically studied thermoelectric properties of Se-alloyed Ge0.95Bi0.05Te via theoretical calculations, structural characterizations, and performance evaluations. Our results indicate that Se-alloying can induce dense point defects with mass/strain-field fluctuations and correspondingly enhance point defect phonon scattering of the Ge0.95Bi0.05Te matrix. Se-alloying might also change chemical bonding strength to introduce resonant states in the base frequency of Ge0.95Bi0.05Te matrix, which can strengthen Umklapp phonon scattering. Finally, a decreased lattice thermal conductivity from ∼1.02 W m−1 K−1 to ∼0.65 W m−1 K−1 at 723 K is obtained in Ge0.95Bi0.05Te1-xSex pellets with increasing the Se content from 0 to 0.3. A peak figure of merit of ∼1.6 at 723 K is achieved in Ge0.95Bi0.05Te0.7Se0.3 pellet, which is ∼77% higher than that of pristine GeTe. This study extends the understanding on the thermoelectric performance of GeTe.
- Published
- 2022