超稳定玻璃的两步失透过程
Two-step devitrification of ultrastable glasses
AI总结：
通过分子动力学模拟揭示超稳定玻璃失透的两步机制：先成核生长受压液滴，后液滴合并释放压力加速失透，解释了与经典Avrami动力学的偏差及巨大长度尺度的来源。
摘要：
超稳定玻璃的发现为玻璃态系统带来了新的挑战。近期实验研究了超稳定玻璃在加热时宏观失透为液体的过程，但缺乏微观分辨率。我们利用分子动力学模拟分析了这一转变的动力学。在最稳定的系统中，失透在很长的时间后才发生，但液体以两步方式出现。在短时间尺度上，我们观察到孤立液滴的稀有成核和缓慢生长，这些液滴中的液体因周围玻璃的刚性而保持在受压状态。在长时间尺度上，当液滴合并成大的区域后，压力得以释放，从而加速失透。这种两步过程产生了与经典Avrami动力学的显著偏差，并解释了表征块体超稳定玻璃失透的巨大长度尺度的出现。我们的研究阐明了玻璃在大温度跃变后的非平衡动力学，这种动力学既不同于平衡弛豫，也不同于老化动力学，并将为未来的实验研究提供指导。
英文摘要：
The discovery of ultrastable glasses has raised novel challenges about glassy systems. Recent experiments studied the macroscopic devitrification of ultrastable glasses into liquids upon heating but lacked microscopic resolution. We use molecular dynamics simulations to analyse the kinetics of this transformation. In the most stable systems, devitrification occurs after a very large time, but the liquid emerges in two steps. At short times, we observe the rare nucleation and slow growth of isolated droplets containing a liquid maintained under pressure by the rigidity of the surrounding glass. At large times, pressure is released after the droplets coalesce into large domains, which accelerates devitrification. This two-step process produces pronounced deviations from the classical Avrami kinetics and explains the emergence of a giant lengthscale characterising the devitrification of bulk ultrastable glasses. Our study elucidates the nonequilibrium kinetics of glasses following a large temperature jump, which differs from both equilibrium relaxation and aging dynamics, and will guide future experimental studies.
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