Graphite under uniaxial compression along the c axis: A parameter to relate out-of-plane strain to in-plane phonon frequency
Graphite under uniaxial compression along the c axis: A parameter to relate out-of-plane strain to in-plane phonon frequency
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DOI：
10.1103/physrevb.92.094108
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发表时间：
2015-09-22
影响因子：
3.7
通讯作者：
Dunstan, D. J.
中科院分区：
文献类型：
--
作者：
Sun, Y. W.;Holec, D.;Dunstan, D. J.
堆叠石墨烯片形成石墨。从石墨烯的E-2g振动模出发，导出了石墨的两个面内振动模E-1u和E-2g（（2）），并将其在压缩条件下的位移视为面内键缩短的结果。Gruneisen参数的值已被报道量化这种关系。然而，为什么这三种模式与压力的变化率不同的原因尚不清楚。在这项工作中，我们引入了新的参数γ '（E2 g）= -0.0131和γ'（E1 u）= 0.0585来量化面外应变对面内振动频率偏移的贡献，这表明π电子的压缩在高压下在石墨和石墨烯中都起着不可忽略的作用。
Stacking graphene sheets forms graphite. Two in-plane vibrational modes of graphite, E-1u and E-2g((2)), are derived from the graphene E-2g mode, the shifts of which under compression are considered as results of the in-plane bond shortening. Values of the Gruneisen parameter have been reported to quantify such a relation. However, the reason why the shift rates of these three modes with pressure differ is unclear. In this work, we introduce new parameters gamma'(E2g) = -0.0131 and gamma'(E1u) = 0.0585 to quantify the contribution of out-of-plane strain to the shift of the in-plane vibrational frequencies, suggesting that the compression of the pi- electrons plays a non-negligible part in both graphite and graphene under high pressure.