近日，中国矿业大学的李海鹏及其研究小组取得一项新进展。经过不懈努力，他们揭示石墨烯/垂直排列碳纳米管/六方氮化硼夹层异质结构界面上的声子热输运过程。相关研究成果已于2024年1月9日在国际知名学术期刊《中国物理快报》上发表。
该研究团队采用分子动力学模拟，计算了石墨烯/碳纳米管/六方氮化硼(Gr/CNTs/hBN)夹层异质结构的界面热阻，其中垂直排列的碳纳米管(VACNT)阵列与石墨烯和六方氮化硼层共价结合。研究发现，Gr/VACNT/hBN夹层异质结构的界面热阻(ITR)比相同平面尺寸的Gr/hBN范德华异质结构的界面热阻(ITR)小一到两个数量级。研究人员观察到共价键有效地增强了Gr和hBN层间的声子耦合，导致Gr和hBN之间态声子密度的重叠因子增加，从而降低了Gr和hBN的ITR。
此外，夹层VACNTs的手性、尺寸(直径和长度)和填充密度对异质结构的ITR有重要影响。在碳纳米管直径和长度相同的情况下，由于手性碳纳米管与Gr和hBN的化学键不同，扶椅型碳纳米管夹层异质结构的ITR要高于锯齿型碳纳米管夹层异质结构。当扶椅型碳纳米管直径增大或长度减小时，夹层异质结构的ITR有减小的趋势。
不仅如此，VACNT堆积密度的增加也导致夹层异质结构的ITR持续下降，这是由于CNTs极高的固有热导率和面外传热通道的增加。本研究有助于理解多层垂直异质结构的热阻机理，并为通过优化夹层热界面材料的设计以调节异质结构的层间热阻提供理论指导。
附：英文原文
Title: Phonon Thermal Transport at Interfaces of a Graphene/Vertically Aligned Carbon Nanotubes/Hexagonal Boron Nitride Sandwiched Heterostructure
Author:
Issue&Volume: 2024-01-09
Abstract: Molecular dynamics simulation is used to calculate the interfacial thermal resistance of a graphene/carbon nanotubes/hexagonal boron nitride (Gr/CNTs/hBN) sandwiched heterostructure, in which vertically aligned carbon nanotube (VACNT) arrays are covalently bonded to graphene and hexagonal boron nitride layers. We find that the interfacial thermal resistance (ITR) of the Gr/VACNT/hBN sandwiched heterostructure is one to two orders of magnitude smaller than the ITR of a Gr/hBN van der Waals heterostructure with the same plane size. It is observed that covalent bonding effectively enhances the phonon coupling between Gr and hBN layers, resulting in an increase in the overlap factor of phonon density of states between Gr and hBN, thus reducing the ITR of Gr and hBN. In addition, the chirality, size (diameter and length), and packing density of sandwich-layer VACNTs have an important influence on the ITR of the heterostructure. Under the same CNT diameter and length, the ITR of the sandwiched heterostructure with armchair-shaped VACNTs is higher than that of the sandwiched heterostructure with zigzag-shaped VACNTs due to the different chemical bonding of chiral CNTs with Gr and hBN. When the armchair-shaped CNT diameter increases or the length decreases, the ITR of the sandwiched heterostructure tends to decrease. Moreover, the increase in the VACNT packing density also leads to a continuous decrease in the ITR of the sandwiched heterostructure, attributed to the extremely high intrinsic thermal conductivity of CNTs and the increase of out-of-plane heat transfer channels. This work may be helpful for understanding the mechanism for ITR in multilayer vertical heterostructures, and provides theoretical guidance for a new strategy to regulate the interlayer thermal resistance of heterostructures by optimizing the design of sandwich layer thermal interface materials.
DOI: 10.1088/0256-307X/41/1/016302
Source: https://cpl.iphy.ac.cn/10.1088/0256-307X/41/1/016302
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