Yuan Kunpeng, Zhang Xiaoliang, Gao Yufei, Tang Dawei
College of New Energy, China University of Petroleum (East China), Qingdao 266580, China.
Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, China.
Phys Chem Chem Phys. 2023 Sep 20;25(36):24883-24893. doi: 10.1039/d3cp03087c.
Pressure is a powerful way to modulate physical properties. Understanding the effect of pressure on the thermal transport properties of thermoelectric materials is of great importance for the efficient design and optimization of thermoelectric performance. In this work, based on first-principles calculations and phonon Boltzmann transport theory, we find that the lattice thermal conductivities of Ag-based chalcopyrites AgXY (X = Al, Ga, and In; Y = S, Se, and Te) are dramatically suppressed by applying pressure. The inherent distorted tetrahedral configuration together with highly delocalized p-orbital electrons promotes the formation of metavalent bonding. The fact of metavalent bonding with a single bonding electron and small electron transfer between neighboring atoms leads to soft low-frequency optical phonons. With the increase of pressure, the softening of acoustic and low-frequency optical phonons induces enhanced anharmonicity and scattering channels. Such strong acoustic-optical phonon coupling results in larger phonon scattering rates and thus lowers the lattice thermal conductivity. These findings not only help unveil the underlying physical mechanisms for the anomalous thermal transport behaviors under high pressure, but also pave the way for the pressure tuning of high-performance Ag-based thermoelectric materials.
压力是调节物理性质的一种有效方式。了解压力对热电材料热输运性质的影响对于高效设计和优化热电性能至关重要。在这项工作中，基于第一性原理计算和声子玻尔兹曼输运理论，我们发现施加压力会显著抑制Ag基黄铜矿AgXY（X = Al、Ga和In；Y = S、Se和Te）的晶格热导率。其固有的扭曲四面体构型以及高度离域的p轨道电子促进了金属价键的形成。具有单个成键电子且相邻原子间电子转移较小的金属价键事实导致了软低频光学声子的形成。随着压力的增加，声学声子和低频光学声子的软化诱导了更强的非谐性和散射通道。这种强烈的声光声子耦合导致更大的声子散射率，从而降低了晶格热导率。这些发现不仅有助于揭示高压下异常热输运行为的潜在物理机制，也为高性能Ag基热电材料的压力调控铺平了道路。
