Tretiakov Konstantin V, Hyżorek Krzysztof
Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznań, Poland.
SmartBee Club, Ltd., Bukowska 27, 62-081 Wysogotowo, Poland.
J Chem Phys. 2021 Feb 7;154(5):054702. doi: 10.1063/5.0036572.
The thermal conductivity of model argon nanowires over a wide range of temperatures from 20 K to 70 K has been calculated using the formula obtained by solving the Boltzmann equation and independently by molecular dynamic (MD) simulations. The theoretical predictions for thermal conductivity take into account the effect of phonon confinement and boundary scattering. Two known theoretical approaches were used. The first approach is based on the solution of the Boltzmann equation with given boundary conditions and uses bulk acoustic phonon dispersion and neglects the phonon confinement effect. The second approach includes also the modification of acoustic phonon dispersion due to spatial confinement. In simulations, the square and circular shapes of wire with the transverse size of nanowires from 4.3 nm to 42.9 nm have been considered. It was found that MD simulation results match the theoretical predictions reasonably well. The obtained results showed that the phonon confinement effect influences the thermal conductivity of nanowires, but the dominant factor decreasing the thermal conductivity with the thickness of nanowires is boundary scattering. Moreover, the values of the interface specular parameter indicate that the specular phonon-boundary scattering prevails over diffuse phonon-boundary scattering.
利用通过求解玻尔兹曼方程得到的公式，并独立地通过分子动力学（MD）模拟，计算了模型氩纳米线在20 K至70 K的宽温度范围内的热导率。热导率的理论预测考虑了声子限制和边界散射的影响。使用了两种已知的理论方法。第一种方法基于具有给定边界条件的玻尔兹曼方程的解，并使用体声学声子色散，忽略声子限制效应。第二种方法还包括由于空间限制对声学声子色散的修正。在模拟中，考虑了横向尺寸从4.3 nm到42.9 nm的方形和圆形纳米线。结果发现，分子动力学模拟结果与理论预测相当吻合。所得结果表明，声子限制效应影响纳米线的热导率，但随着纳米线厚度降低热导率的主导因素是边界散射。此外，界面镜面参数的值表明，镜面声子-边界散射比漫射声子-边界散射更占优势。
