金属纳米颗粒的热导率

本文使用统计模拟方法对金属纳米颗粒的电子平均自由程进行了计算,并考察了纳米颗粒的晶格比热和声子平均群速度,最后应用动力学理论对纳米颗粒的电子热导率和声子热导率分别进行了求解.研究结果表明:具有相同特征尺寸的方形、球形纳米颗粒的无量纲电子(或声子)平均自由程比较接近.金属纳米颗粒的电子热导率远大于声子热导率;电子、声子热导率随着直径减小呈现降低趋势,而电子热导率的颗粒尺度依赖性比声子热导率更为明显;随着颗粒直径进一步减小,声子热导率与电子热导率趋于同一数量级.当纳米颗粒特征尺寸大于4倍块材电子(或声子)平均自由程,其电子(或声子)热导率的颗粒尺度依赖性将减弱.

Thermal conductivity of metallic nanoparticle

Concerning metallic nanoparticles, a statistical simulation method to predict the electron mean free path of a nanoparticleis developed. And the phonon-contributed specific heat and phonon group velocity are also analyzed. Then, the kinetic theory is used to obtain the electron thermal conductivity and the lattice thermal conductivity of the nanoparticles. The size dependence of these properties is further discussed. It turns out that the electron mean free path of a square nanoparticle approximates to that of a circle nanoparticle if nanoparticles are of the same characteristic length. The electron thermal conductivity is much higher than the lattice thermal conductivity on the nanoscale. Either electron or lattice thermal conductivity of nanoparticles declines with diameter decreasing, while the size dependence of electron thermal conductivity is more obvious. However, if the diameter decreases to quite a small size, the electron thermal conductivity will become as low as the lattice thermal conductivity. In addition, the electron/lattice thermal conductivity of a nanoparticle will become less size-dependent if its characteristic length is 4 times larger than corresponding bulk electron/phonon mean free path.