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Phase Modulation Enabled High Thermoelectric Performance in Polycrystalline GeSe0.75Te0.25
Wang, Zhiran1,2; Wu, Hong3,4; Zhang, Bin5; Dai, Lu1,2; Huo, Yufeng1,2; Huang, Yuling3,4; Han, Guang6; Lu, Xu3,4; Zhou, Xiaoyuan3,4,5; Wang, Guoyu1,2
2022-03-23
摘要The structure-property link is inherent to materials. Hexagonal Ge4Se3Te phase, with special Ge-Ge cationic bonding and distinctive from other IV-VI compounds, reveals thermoelectric (TE) performance far below the common values for IV-VI compounds. Here, it is shown that its TE performance can be substantially enhanced by phase modulation: increasing sintering temperature from 573 to 773 K leads to the decomposition of hexagonal phase into a composite of orthorhombic and rhombohedral phases, which significantly improves TE performance at T <= 550 K; Sb/Cd doping stabilizes the rhombohedral phase, compensates the hole concentration, and strengthens the phonon scattering, which further enhances the TE performance over the whole temperature range. The theoretical calculation reveals that the rhombohedral phase has a more favorable electronic band structure than the hexagonal phase for achieving higher electrical transport properties. The optimized TE performance is obtained in rhombohedral Ge0.90Sb0.08Cd0.02Se0.75Te0.25, with a zT(max) of 1.36 at 778 K and zT(ave) of 0.73 from 322 to 778 K, which are among the highest values in the Se-rich side of Ge(Se, Te) system, and one order higher than those in the hexagonal phase. The study sheds light on the validity of phase modulation for TE performance optimization in Ge(Se, Te)-based material systems.
关键词thermoelectric Ge Se-4 Te-3 phase modulation figure of merit electronic band structure
DOI10.1002/adfm.202111238
发表期刊ADVANCED FUNCTIONAL MATERIALS
ISSN1616-301X
页码9
通讯作者Zhou, Xiaoyuan(xiaoyuan2013@cqu.edu.cn) ; Wang, Guoyu(guoyuw@cigit.ac.cn)
收录类别SCI
WOS记录号WOS:000771872300001
语种英语