发表机构
Seoul National University; Research Institute of Advanced Materials, Seoul National University; Center for AI and Natural Sciences, Korea Institute for Advanced Study; Incheon National University（首尔大学; 首尔大学先进材料研究所; 韩国高等研究院人工智能与自然科学中心; 仁川国立大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用预训练机器学习原子间势结合分子动力学与玻尔兹曼输运方程，量化了氮化铝中氧缺陷对热导率的限制作用，验证了独立散射近似在低浓度下的有效性，并揭示了高浓度下的偏离现象。
AI 中文摘要
氮化铝（AlN）是一种重要的热管理材料，其高晶格热导率受到氧杂质的强烈抑制。我们利用预训练的通用机器学习原子间势（MLIPs）、分子动力学（MD）和声子玻尔兹曼输运计算，研究了与氧相关缺陷的声子散射。针对声子色散和本征热导率，我们将多种预训练MLIPs与密度泛函理论进行了基准比较。为平衡精度与计算速度，我们在MD模拟中采用了紧凑型SevenNet-Nano模型的微调版本。蒙特卡洛退火支持束缚态$V_{\mathrm{Al}}(\mathrm{O_N})_3$复合物的形成，其散射行为不同于其孤立组分。从过剩谱能量密度（SED）线宽提取的缺陷散射率在低氧含量下与谐波$T$-矩阵预测合理一致，支持独立散射体近似。将这些散射率纳入具有玻色-爱因斯坦统计的迭代玻尔兹曼输运方程，所得热导率与实验值相当，并捕捉到其随氧含量增加而下降的趋势。然而，在高浓度下，散射率偏离与氧含量的线性标度关系，表明独立缺陷和本征声子描述的局限性。这些结果展示了一种利用预训练MLIPs量化缺陷限制热输运的高效方法，并为超出稀缺陷近似之外的杂质效应提供了见解。
英文摘要
Aluminum nitride (AlN) is an important thermal management material whose high lattice thermal conductivity is strongly suppressed by oxygen impurities. We investigate phonon scattering by oxygen-related defects using pretrained universal machine-learning interatomic potentials (MLIPs), molecular dynamics (MD), and phonon Boltzmann transport calculations. Several pretrained MLIPs are benchmarked against density functional theory for phonon dispersions and pristine thermal conductivity. To balance accuracy and computational speed, we use a fine-tuned version of the compact SevenNet-Nano model for MD simulations. Monte Carlo annealing supports the formation of bound $V_{\mathrm{Al}}(\mathrm{O_N})_3$ complexes, whose scattering differs from that of their isolated constituents. Defect scattering rates extracted from excess spectral energy density (SED) linewidths agree reasonably with harmonic $T$-matrix predictions at low oxygen contents, supporting the independent-scatterer approximation. Incorporating these rates into an iterative Boltzmann transport equation with Bose--Einstein statistics yields thermal conductivities comparable to experimental values and captures their observed decrease with oxygen content. At high concentrations, however, the scattering rate deviates from linear scaling with oxygen content, suggesting limitations of independent-defect and pristine-phonon descriptions. These results demonstrate an efficient approach using pretrained MLIPs to quantify defect-limited thermal transport and provide insights into impurity effects beyond the dilute-defect approximation.
Comments21 pages, 15 figures
