Cacciuto A, Frenkel D
FOM Institute for Atomic and Molecular Physics,Kruislaan 407, 1098 SJ Amsterdam, The Netherlands.
J Phys Chem B. 2005 Apr 14;109(14):6587-94. doi: 10.1021/jp0456483.
The usual derivation of classical nucleation theory is inappropriate for crystal nucleation. In particular, it leads to a seriously flawed estimate of the pressure inside a critical nucleus. This has consequences for the prediction of possible metastable phases during the nucleation process. In this paper, we reanalyze the theory for crystal nucleation based on the thermodynamics of small crystals suspended in a liquid, due to Mullins (J. Chem. Phys. 1984, 81, 1436). As an illustration of the difference between the classical picture and the present approach, we consider a numerical study of crystal nucleation in binary mixtures of hard spherical colloids with a size ratio of 1:10. The stable crystal phase of this system can be either dense or expanded. We find that, in the vicinity of the solid-solid critical point where the crystallites are highly compressible, small crystal nuclei are less dense than large nuclei. This phenomenon cannot be accounted for by either classical nucleation theory or by the Gibbsian droplet model.
经典成核理论的常规推导不适用于晶体成核。特别是，它会导致对临界核内部压力的估计存在严重缺陷。这对成核过程中可能的亚稳相的预测产生影响。在本文中，我们基于穆林斯（《化学物理杂志》，1984年，81卷，1436页）提出的悬浮在液体中的小晶体热力学，重新分析晶体成核理论。作为经典图景与当前方法差异的一个例证，我们考虑了对尺寸比为1:10的硬球形胶体二元混合物中晶体成核的数值研究。该系统的稳定晶相可以是致密的或膨胀的。我们发现，在微晶具有高度可压缩性的固 - 固临界点附近，小晶核比大晶核密度更低。这种现象既不能用经典成核理论解释，也不能用吉布斯液滴模型解释。
