石墨烯低温热膨胀和声子弛豫时间随温度的变化规律

发布时间：2018-03-19 02:01

本文选题：石墨烯　切入点：低温热膨胀系数　出处：《物理学报》2017年22期 　论文类型：期刊论文

【摘要】：考虑到原子非简谐振动和电子-声子相互作用,用固体物理理论和方法研究了石墨烯格林艾森参量和低温热膨胀系数以及声子弛豫时间随温度的变化规律,探讨了原子非简谐振动项对它们的影响.结果表明:1)在低于室温的温度范围内,石墨烯的热膨胀系数为负值,随着温度的升高,其热膨胀系数的绝对值单调增加,室温热膨胀系数为-3.64×10~(-6)K~(-1);2)简谐近似下的格林艾森参量为零.考虑到非简谐项后,格林艾森参量在1.40-1.42之间并随温度升高而缓慢增大,几乎成线性关系,第二非简谐项对格林艾森参量的影响小于第一非简谐项;3)石墨烯声子弛豫时间随着温度的升高而减小,其中,温度很低(T10 K)时变化很快,此后变化很慢,当温度不太低(T300 K)时,声子弛豫时间与温度几乎成反比关系.
[Abstract]:Considering the atomic anharmonic vibration and the electron-phonon interaction, the Gleansen parameters, the low temperature thermal expansion coefficient and the phonon relaxation time of graphene are studied by means of solid state physics theory and method. The effect of atomic anharmonic oscillations on them is discussed. The results show that in the temperature range below room temperature, the thermal expansion coefficient of graphene is negative, and the absolute value of thermal expansion coefficient increases monotonously with the increase of temperature. The coefficient of thermal expansion at room temperature is -3.64 脳 10 ~ (10) K ~ (1) ~ (1) ~ (2)) the Green Issen parameter is zero under the simple harmonic approximation. Considering the anharmonic term, the Green Issen parameter increases slowly in the range of 1.40-1.42 and increases with the increase of temperature, which is almost linearly related. The effect of the second anharmonic term on the GreenIssen parameter is smaller than that of the first anharmonic term (3). The phonon relaxation time of graphene decreases with the increase of temperature. The change of phonon relaxation time of graphene decreases rapidly at very low temperature (T10K), and then changes slowly after that, when the temperature is not too low (T300K), The phonon relaxation time is almost inversely proportional to temperature.
【作者单位】：重庆文理学院电子电气工程学院重庆市高校新型储能器件及应用工程研究中心;福州大学机械工程及其自动化学院;
【基金】：国家自然科学基金(批准号:51505086) 重庆市教委科技项目(批准号:KJ1601118,KJ1601111) 重庆市基础与前沿研究项目(批准号:cstc2015jcyjA40054)资助的课题~~
【分类号】：O613.71

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