论文标题
Akhiezer机制在室温下占主导地位的无定形宣传
Akhiezer Mechanism Dominates Relaxation of Propagons in Amorphous at Room Temperature
论文作者
论文摘要
宣传在调整纳米结构无形材料的导热率中起着重要作用。尽管已经取得了进步来定量评估用分子动力学的宣传时间的放松时间，但潜在的弛豫机制仍未开发。在这里，我们根据Akhiezer模型在室温下研究了无定形硅，无定形二氧化硅和无定形硅的宣传过程，该参数是通过执行晶格动力学和分子动力学分析来评估的。结果表明，Akhiezer模型可以很好地再现通过各种测量方法获得的实验结果，这表明Akhiezer机制在室温下占主导地位的宣传过程。此外，我们表明，适当的宣传速度约为Debye声速的80％，与横向模式的音速相当。我们还揭示了分散子对这些无定形的总热导率的贡献相似，约为1 w/m k，而宣传的贡献取决于材料的差异很大，这在无定形硅和硅的30％方面，但在无晶硅硝基盐中的贡献高达70％。
Propagons play an important role in tuning the thermal conductivity of nanostructured amorphous materials. Although advances have been made to quantitatively evaluate the relaxation time of propagons with molecular dynamics, the underlying relaxation mechanism remains unexplored. Here, we investigate the relaxation process of propagons in amorphous silicon, amorphous silica, and amorphous silicon nitride at room temperature in terms of Akhiezer model, the parameters of which were evaluated by performing lattice dynamics and molecular dynamics analysis. The results show that the Akhiezer model can well reproduce experimental results obtained by various kinds of measurement methods, indicating that Akhiezer mechanism dominates the relaxation process of propagons at room temperature. Moreover, we show that the appropriate sound speed of propagons is around 80% of the Debye sound speed and comparable to that of the sound speed of the transversal modes. We also reveal that the contribution of diffusons to the total thermal conductivity of these amorphous is similar, which is around 1 W/m K, while the contribution of propagons varies significantly depending on the materials, which is 30% in amorphous silicon and silica but can be as high as 70% in amorphous silicon nitride.
