论文标题
扭曲的石墨纳米纤维的最小导热率
Minimum thermal conductance of twisted-layer graphite nanofibers
论文作者
论文摘要
我们研究了扭曲的石墨纳米纤维的热传输特性。我们表明，在存在扭曲层的情况下，石墨纳米纤维的调子导电量与扭曲角度差异很大，并且可以在两个临界角度以$θ_1$和$θ_2$符合规则$θ_1$θ_1$ + $ + $ + $ + $θ_1$ = $ 180^0 $或完全$θ$θ$θ$ 90^0^0^0^0^0^0^0. $θ_1$ + $ + $θ_1$ = $ + $ + $ + $ + $ + $θ_1$ = $θ_1，在某些结构中，可以实现大约50％的声子导电的降低。我们揭示了扭曲效果主要影响光学模式，几乎没有改变声学模式。在较高且更多的范霍夫奇异性中，状态的声子密度的奇异性也可见。我们还指出，具有扭曲角的导热电导的行为与扭曲和非扭曲层之间的重叠区域的变化有关并主导。证明有限尺寸的效果在定义局部最小值的临界角度方面起着至关重要的作用，在局部最小值中，这些角度取决于所研究的纳米纤维的大小，尤其是在锯齿形和扶手椅边缘的宽度之间的比例。
We study the thermal transport properties of twisted-layer graphite nanofibers. We show that in the presence of a twisted layer, the phonon thermal conductance of a graphite nanofiber varies remarkably with the twisted angle and can reach minimum values either at two critical angles $θ_1$ and $θ_2$ that conform to the rule $θ_1$ + $θ_1$ = $180^0$ or exactly at the angle $θ$ = $90^0$. A reduction of roughly 50% of the phonon thermal conductance can be achieved in some structures. We unveil that the twisting effect mainly influences the optical modes, leaving almost unaltered the acoustic ones. The effect is also visible in the higher and more numerous van Hove singularities of the phonon density of states. We also point out that the behavior of the thermal conductance with the twisted angle is associated with and dominated by the alteration in the overlap area between the twisted and non-twisted layers. The finite-size effect is demonstrated to play an essential role in defining the critical angles at the local minimums, where these angles are dependent on the size of the investigated nanofibers, in particular on the proportion between the widths of zigzag and armchair edges.
