Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
Phys Rev Lett. 2018 Oct 12;121(15):155701. doi: 10.1103/PhysRevLett.121.155701.
The fundamental study of phase transition kinetics has motivated experimental methods toward achieving the largest degree of undercooling possible, more recently culminating in the technique of rapid, quasi-isentropic compression. This approach has been demonstrated to freeze water into the high-pressure ice VII phase on nanosecond timescales, with some experiments undergoing heterogeneous nucleation while others, in apparent contradiction, suggest a homogeneous nucleation mode. In this study, we show through a combination of theory, simulation, and analysis of experiments that these seemingly contradictory results are in agreement when viewed from the perspective of classical nucleation theory. We find that, perhaps surprisingly, classical nucleation theory is capable of accurately predicting the solidification kinetics of ice VII formation under an extremely high driving force (|Δμ/k_{B}T|≈1) but only if amended by two important considerations: (i) transient nucleation and (ii) separate liquid and solid temperatures. This is the first demonstration of a model that is able to reproduce the experimentally observed rapid freezing kinetics.
相变动力学的基础研究激发了实验方法的发展，以实现尽可能大的过冷度，最近最终达到了快速、准等熵压缩的技术。该方法已被证明可在纳秒时间尺度内将水冷冻成高压冰 VII 相，一些实验经历了异质成核，而另一些实验则与经典成核理论相矛盾，表明存在均相成核模式。在这项研究中，我们通过理论、模拟和实验分析的结合表明，从经典成核理论的角度来看，这些看似矛盾的结果是一致的。我们发现，也许令人惊讶的是，经典成核理论能够准确预测在极高驱动力(|Δμ/k_{B}T|≈1)下冰 VII 形成的凝固动力学，但前提是要修正两个重要考虑因素：(i)瞬态成核和(ii) 液体和固体的单独温度。这是第一个能够再现实验观察到的快速冷冻动力学的模型的演示。
