Unusual Twisting Phonons and Breathing Modes in Tube‐Terminated Phosphorene Nanoribbons and Their Effects on Thermal Conductivity,Advanced Functional Materials

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Unusual Twisting Phonons and Breathing Modes in Tube‐Terminated Phosphorene Nanoribbons and Their Effects on Thermal Conductivity
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2017-11-07 , DOI: 10.1002/adfm.201702776
Xiangjun Liu ₁ , Junfeng Gao ₁ , Gang Zhang ₁ , Yong-Wei Zhang ₁

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By studying tube‐terminated phosphorene nanoribbons (PNRs), it is found that unusual phonon and thermal properties can emerge from topologically new edges. The lattice dynamics calculations show that in tube‐terminated PNRs, the breaking of rotation symmetry suppresses the degeneracy of phonon modes, causing the emergence of twisting mode. An anomalous change of an out‐of‐plane acoustic mode to breathing modes with nonzero energy at the center of Brillouin zone occurs when the phosphorene sheet is converted into a tube‐terminated PNR. These unusual twisting and breathing modes provide a larger phase space for scattering phonons, thus explaining the low thermal conductivity of tube‐terminated PNRs revealed by molecular dynamics calculations. Due to the change in the stress field distribution caused by the tube edge, a nearly strain‐independent thermal conductivity in tube‐terminated PNRs is observed, which is in contrast to the apparent enhancement of thermal conductivity in pristine and dimer‐terminated PNRs under tensile strain. The work reveals intriguing phononic and thermal behaviors of tube‐terminated 2D materials.

中文翻译：

管端磷纳米带中的异常扭曲声子和呼吸模式及其对热导率的影响

通过研究管端的磷烯纳米带（PNR），发现异常的声子和热学性质可能会从拓扑学的新边缘出现。晶格动力学计算表明，在管端PNR中，旋转对称性的破坏抑制了声子模的简并性，从而导致扭曲模的出现。当磷片转化为管端PNR时，在布里渊区的中心处，平面外声学模式向呼吸模式的异常改变为非零能量。这些异常的扭曲和呼吸模式为散射声子提供了更大的相空间，从而解释了分子动力学计算揭示的管端PNR的低热导率。由于管缘引起的应力场分布变化，在管端接的PNR中观察到几乎不依赖于应变的热导率，这与在拉伸应变下原始和二聚体端接的PNR中的导热率明显提高相反。这项工作揭示了管端2D材料的有趣的声子和热行为。

更新日期：2017-11-07

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