Nucleation kinetics in deionized charged colloidal model systems: a quantitative study by means of classical nucleation theory.
Nucleation kinetics in deionized charged colloidal model systems: a quantitative study by means of classical nucleation theory.
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DOI：
10.1103/physreve.75.051405
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发表时间：
2007-05
期刊：
影响因子：
--
通讯作者：
P. Wette;H. Schöpe
中科院分区：
文献类型：
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作者：
P. Wette;H. Schöpe
本文研究了在无盐条件下以体心立方结构结晶的荷电胶体模型体系的成核动力学，其粒子数密度范围为18 μ m（-3）≤ n ≤ 66.3 μ m（-3）。我们采用直接的视频显微镜观察单个成核事件，以获得时间分辨的成核速率密度。偏光显微镜和静态光散射与Avrami理论相结合的固体被用来确定在高过冷度的稳态成核率。观察到不同方法得到的最终成核速率密度J是一致的。通过增加熔体和晶体之间的化学势差Δ mu约一个数量级，J在约七个数量级上从10（9）m（-3）s（-1）增加到10（17）m（-3）s（-1）。数据可以很好地分析和解释，使用经典的成核理论（CNT）导致线性增加的熔体-晶体表面张力。令人惊讶的是，与其他系统（金属;硬球胶体）相比，降低的表面张力大约大一个数量级。晶核的临界半径下降到一个非常小的值1.5配位壳。所确定的动力学前因子比CNT计算的前因子小10个数量级。
We have studied the nucleation kinetics of charged colloidal model systems under salt free conditions crystallizing in bcc structure covering a wide range of particle number densities 18 microm(-3) < or =n< or =66.3 microm(-3). We employed direct video-microscopic observation of individual nucleation events to obtain time resolved nucleation rate densities. Polarization microscopy and static light scattering on the resulting solids in combination with Avrami theory is used to determine the steady state nucleation rate at high undercoolings. The final nucleation rate densities J from different methods are observed to be consistent with each other. By increasing the difference in the chemical potential between melt and crystal Delta mu about one order of magnitude J increases from 10(9)m(-3)s(-1) to 10(17)m(-3)s(-1) over approximately seven orders of magnitude. The data can be well analyzed and interpreted using classical nucleation theory (CNT) leading to a linearly increasing melt-crystal surface tension. Surprisingly, the reduced surface tension is about one order of magnitude larger compared to other system (metals; hard sphere colloids). The critical radius of the crystal nuclei is decreasing down to a very small value of 1.5 coordination shells. The determined kinetic prefactors are up to 10 orders of magnitude smaller than the prefactor calculated by CNT.