Abstract The mechanisms governing mechanical dissipation in amorphous tantala are studied at microscopic scale via Molecular Dynamics simulations, namely by mechanical spectroscopy in a wide range of temperature and frequency. We find that dissipation is associated with irreversible atomic rearrangements with a sharp cooperative character, involving tens to hundreds of atoms arranged in spatially extended clusters of polyhedra. Remarkably, at low temperature we observe an excess of plastically rearranging oxygen atoms which correlates with the experimental peak in the macroscopic mechanical losses. A detailed structural analysis reveals preferential connections of the irreversibly rearranging polyhedra, corresponding to edge and face sharing. These results might lead to microscopically informed design rules for reducing mechanical losses in relevant materials for structural, optical, and sensing applications.

中文翻译：

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动态力学光谱揭示了控制无定形坦塔拉中耗散的非局部协同原子运动

摘要 通过分子动力学模拟，即在宽温度和频率范围内的机械光谱，在微观尺度上研究了控制非晶钽中机械耗散的机制。我们发现耗散与不可逆的原子重排有关，具有明显的协同特性，涉及排列在空间扩展的多面体簇中的数十到数百个原子。值得注意的是，在低温下，我们观察到过量的塑性重排氧原子，这与宏观机械损失的实验峰值相关。详细的结构分析揭示了不可逆重排多面体的优先连接，对应于边和面共享。