Kielar Samuel, Li Chen, Huang Han, Hu Renjiu, Slebodnick Carla, Alatas Ahmet, Tian Zhiting
Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA.
MOE Key Laboratory of Low-grade Energy Utilization Technologies and Systems, School of Energy & Power Engineering, Chongqing University, Chongqing, China.
Nat Commun. 2024 Aug 14;15(1):6981. doi: 10.1038/s41467-024-51377-8.
Understanding thermal transport mechanisms in phase change materials is critical to elucidating the microscopic picture of phase transitions and advancing thermal energy conversion and storage. Experiments consistently show that cubic phase germanium telluride (GeTe) has an unexpected increase in lattice thermal conductivity with rising temperature. Despite its ubiquity, resolving its origin has remained elusive. In this work, we carry out temperature-dependent lattice thermal conductivity calculations for cubic GeTe through efficient, high-order machine-learned models and additional corrections for coherence effects. We corroborate the calculated phonon properties with our inelastic X-ray scattering measurements. Our calculated lattice thermal conductivity values agree well with experiments and show a similar increasing trend. Through additional bonding strength calculations, we propose that a major contributor to the increasing lattice thermal conductivity is the strengthening of second-nearest neighbor interactions. The findings herein serve to deepen our understanding of thermal transport in phase-change materials.
了解相变材料中的热传输机制对于阐明相变的微观图像以及推进热能转换和存储至关重要。实验一致表明，立方相碲化锗（GeTe）的晶格热导率会随着温度升高而出现意外增加。尽管其普遍存在，但其起源仍难以确定。在这项工作中，我们通过高效的高阶机器学习模型以及对相干效应的额外校正，对立方相GeTe进行了与温度相关的晶格热导率计算。我们用非弹性X射线散射测量结果证实了计算得到的声子特性。我们计算得到的晶格热导率值与实验结果吻合良好，并呈现出类似的上升趋势。通过额外的键合强度计算，我们提出晶格热导率增加的一个主要因素是次近邻相互作用的增强。本文的研究结果有助于加深我们对相变材料中热传输的理解。
