Publication: Enhanced thermoelectric performance and low thermal conductivity in Cu2GeTe3 with identified localized symmetry breakdown
Program
KU-Authors
KU Authors
Co-Authors
Qin, Feiyu
Hu, Lei
Zhu, Yingcai
Li, Yushan
Wang, Haitao
Wu, Haijun
Peng, Jun
Shi, Wen
Ding, Xiangdong
Publication Date
Language
Type
Embargo Status
Journal Title
Journal ISSN
Volume Title
Alternative Title
Abstract
Highly efficient and eco-friendly thermoelectric generators rely on low-cost and nontoxic semiconductors with high symmetry and ultralow lattice thermal conductivity kappa L. We report the rational synthesis of the novel cubic (Ag, Se)-doped Cu2GeTe3 semiconductors. A localized symmetry breakdown (LSB) was found in the composition of Cu1.9Ag0.1GeTe1.5Se1.5 (i.e., CAGTS15) with an ultralow kappa L of 0.37 W/mK at 723 K, the lowest value outperforming all Cu2GeCh3 (Ch = S, Se, and Te). A joint investigation of synchrotron X-ray techniques identifies the LSB embedded into the cubic CAGTS15 host matrix. This LSB is an angstrom ngstro''m-scale orthorhombic symmetry unit, characteristic of multiple bond lengths, large anisotropic atomic displacements, and distinct local chemical coordination of anions. Computational results highlight that such an unusual orthorhombic symmetry demonstrates low-frequency phonon modes, which become softer and more predominant with increasing temperatures. This unconventional LSB promotes bond complexity and phonon scattering, highly beneficial for extraordinarily low lattice thermal conductivity.
Source
Publisher
American Chemical Society
Subject
Chemistry, inorganic and nuclear
Citation
Has Part
Source
Inorganic Chemistry
Book Series Title
Edition
DOI
10.1021/acs.inorgchem.3c00350