Liu Yin, Jin Lei, Pandey Tribhuwan, Sun Haoye, Liu Yuzi, Li Xun, Rodriguez Alejandro, Wang Yueyin, Zhou Tao, Chen Rui, Sun Yongwen, Yang Yang, Chrzan Daryl C, Lindsay Lucas, Wu Junqiao, Yao Jie
Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC, USA.
Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA, USA.
Nat Mater. 2025 May;24(5):728-734. doi: 10.1038/s41563-024-02108-3. Epub 2025 Feb 12.
Dislocations in van der Waals (vdW) layered nanomaterials induce strain and structural changes that substantially impact thermal transport. Understanding these effects could enable the manipulation of dislocations for improved thermoelectric and optoelectronic applications, but experimental insights remain limited. In this study, we use synthetic Eshelby twisted vdW GeS nanowires (NWs) with single screw dislocations as a model system to explore the interplay between dislocation-induced structural modifications and lattice thermal conductivity. Our measurements reveal a monoclinic structure stabilized by the dislocation, leading to a substantial drop in thermal conductivity for larger-diameter NWs (70% at room temperature), supported by first-principles calculations. Interestingly, we also find an anomalous enhancement of thermal conductivity with decreasing diameter in twisted NWs, contrary to typical trends in non-twisted GeS NWs. This is attributed to increased conductivity near the NW cores due to compressive strain around the central dislocations, and aligns with a density-functional-theory-informed core-shell model. Our results highlight the critical role of dislocations in thermal conduction, providing fundamental insights for defect and strain engineering in advanced thermal applications.
范德华（vdW）层状纳米材料中的位错会引起应变和结构变化，这对热传输有重大影响。了解这些效应有助于通过操纵位错来改进热电和光电应用，但目前实验方面的认识仍然有限。在本研究中，我们使用具有单螺旋位错的合成埃舍尔比扭曲vdW GeS纳米线（NWs）作为模型系统，来探索位错诱导的结构修饰与晶格热导率之间的相互作用。我们的测量结果表明，位错使单斜结构得以稳定，导致较大直径NWs的热导率大幅下降（室温下下降70%），第一性原理计算也支持这一结果。有趣的是，我们还发现，与非扭曲GeS NWs的典型趋势相反，扭曲NWs的热导率随直径减小而反常增强。这归因于中心位错周围的压缩应变使NW核心附近的电导率增加，这与密度泛函理论指导的核壳模型相符。我们的结果突出了位错在热传导中的关键作用，为先进热应用中的缺陷和应变工程提供了基础认识。
