材料科学
微观结构
石墨烯
氧化物
剪切(地质)
热电效应
复合材料
热电材料
冶金
纳米技术
热力学
热导率
物理
作者
Junqing Zheng,Yi Wen,Sining Wang,Yichen Li,Siqi Wang,Zhe Zhao,Shan Liu,Shibo Liu,Xiang Gao,Li‐Dong Zhao
标识
DOI:10.1002/adfm.202401735
摘要
Abstract Bi 6 Cu 2 Se 4 O 6 is considered as an ideal n ‐type thermoelectric material to pair with p ‐type BiCuSeO for preparing oxyselenide‐based thermoelectric devices, but its thermoelectric performance is limited by poor electrical conductivity. In this research, the reduced graphene oxide (rGO) nanosheets are introduced into Bi 6 Cu 2 Se 3.6 Cl 0.4 O 6 matrix through liquid‐phase shear exfoliation to modify the microstructure. rGO can insert into matrix grains as intercalations, or embed into grain boundaries as wetting phase, and prompt grain alignment, which contributes to the significantly enhanced carrier mobility, thus leading to an improvement in electrical conductivity from ≈15 S cm −1 to ≈230 S cm −1 at 303 K. Whereafter, the effective donor dopant Nb is chosen to substitute Bi. The carrier concentration is increased without damaging the carrier mobility, resulting in a further improved electrical conductivity of ≈840 S cm −1 at 303 K. Lattice thermal conductivity is also suppressed owing to the intensive phonon scattering by point defects and grain boundaries. Ultimately, a record‐breaking peak ZT ≈0.5 (873 K) and average ZT ≈0.3 (303–873 K) can be achieved in Bi 5.91 Nb 0.09 Cu 2 Se 3.6 Cl 0.4 O 6 + 0.5% rGO. The microstructure optimization method in this research effectively improves thermoelectric performance, and is anticipated to be applied in other thermoelectrics.
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