Jie Zhang, Li Zhou, Xiaohong Xia, Yun Gao, Zhongbing Huang
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引用次数: 0
Abstract
Decoupling electrical and thermal properties to enhance the figure of merit of thermoelectric materials underscores an in-depth understanding of the mechanisms that govern the transfer of charge carriers. Typically, a factor that contributes to the optimization of thermal conductivity is often found to be detrimental to the electrical transport properties. Here, we systematically investigated 26 dimeric MX2-type compounds (where M represents a metal and X represents a nonmetal element) to explore the influence of the electronic configurations of metal cations on lattice thermal transport and thermoelectric performance using first-principles calculations. A principled scheme has been identified that the filled outer orbitals of the cation lead to a significantly lower lattice thermal conductivity compared to that of the partly occupied case for MX2, due to the much weakened bonds manifested by the shallow potential well, smaller interatomic force constants, and higher atomic displacement parameters. Based on these findings, we propose two ionic compounds, BaAs and BaSe2, to realize reasonable high electrical conductivities through the structural anisotropy caused by the inserted covalent X2 dimers while still maintaining the large lattice anharmonicity. The combined superior electrical and thermal properties of BaSe2 lead to a high n-type thermoelectric ZT value of 2.3 at 500 K. This work clarifies the structural origin of the heat transport properties of dimeric MX2-type compounds and provides an insightful strategy for developing promising thermoelectric materials.
期刊介绍:
Energy & Environmental Materials (EEM) is an international journal published by Zhengzhou University in collaboration with John Wiley & Sons, Inc. The journal aims to publish high quality research related to materials for energy harvesting, conversion, storage, and transport, as well as for creating a cleaner environment. EEM welcomes research work of significant general interest that has a high impact on society-relevant technological advances. The scope of the journal is intentionally broad, recognizing the complexity of issues and challenges related to energy and environmental materials. Therefore, interdisciplinary work across basic science and engineering disciplines is particularly encouraged. The areas covered by the journal include, but are not limited to, materials and composites for photovoltaics and photoelectrochemistry, bioprocessing, batteries, fuel cells, supercapacitors, clean air, and devices with multifunctionality. The readership of the journal includes chemical, physical, biological, materials, and environmental scientists and engineers from academia, industry, and policy-making.