We study thermal conductivity (κ) of amorphous silicon boron nitride (a‐SiBN) for different compositions and densities as a function of temperature using density functional theory (DFT) calculations and equilibrium molecular dynamic (MD) simulations. Our library of amorphous structures consists of network models comprising 100‐200 atoms and large‐scale models with up to 57 000 atoms generated using the empirical Marian‐Gastreich two‐body potential. Crystalline structures within the Si₃N₄‐BN system are considered as well. We use 2 distinct approaches to compute thermal conductivity of a‐SiBN. To estimate κ in the high‐temperature limit we feed Clarke's phenomenological model with elasticity data obtained by DFT calculations. We further perform equilibrium MD simulations and apply the Green‐Kubo method. This approach shows decrease of κ with increasing temperature and provides results at high temperatures that agree with results derived within Clarke's model. We find that κ of a‐SiBN depends on composition and increases as the BN content in the structure increases. The effect is pronounced at low temperature but almost vanishes at high temperature. Furthermore, thermal conductivity depends on density and porosity, with a linear relation between κ and density.

中文翻译：

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组成，密度和温度对非晶硅氮化硼热导率影响的计算研究

我们使用密度泛函理论（DFT）计算和平衡分子动力学（MD）模拟研究了非晶硅氮化硼（a-SiBN）在不同组成和密度下随温度变化的热导率（κ）。我们的无定形结构库由包含100-200个原子的网络模型和使用经验性Marian-Gastreich两体势能生成的多达57 000个原子的大规模模型组成。Si ₃ N ₄内的晶体结构‐BN系统也被考虑。我们使用2种不同的方法来计算a-SiBN的热导率。为了估算高温极限中的κ，我们将通过DFT计算获得的弹性数据输入Clarke的现象学模型。我们进一步执行平衡MD模拟，并应用Green-Kubo方法。这种方法显示出随着温度升高，κ减小，并且在高温下提供的结果与Clarke模型中得出的结果一致。我们发现，a-SiBN的κ取决于组成，并随着结构中BN含量的增加而增加。在低温下效果明显，但在高温下几乎消失。此外，导热系数取决于密度和孔隙率，并且在κ和密度之间具有线性关系。