Wette Patrick, Engelbrecht Andreas, Salh Roushdey, Klassen Ina, Menke Dirk, Herlach Dieter M, Roth Stephan V, Schöpe Hans Joachim
Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), D-51170 Köln, Germany.
J Phys Condens Matter. 2009 Nov 18;21(46):464115. doi: 10.1088/0953-8984/21/46/464115. Epub 2009 Oct 27.
We studied the competition between heterogeneous and homogeneous nucleation of an aqueous suspension of charged colloidal spheres close to the container walls. Samples of equilibrium crystalline structure were shear-melted and the metastable melt left to solidify after the cessation of shear. The crystallization kinetics was monitored using time-resolved scattering techniques: at low particle number densities n we applied an improved static light scattering method while at large particle concentrations ultra-small-angle x-ray scattering was applied for the first time. Our results show some unexpected behavior: the heterogeneous nucleation at the container walls is delayed in comparison to the homogeneous bulk nucleation and its rate density appears surprisingly slightly smaller, demonstrating the complexity of the observed crystallization process.
我们研究了靠近容器壁的带电胶体球水悬浮液的非均匀成核与均匀成核之间的竞争。对平衡晶体结构的样品进行剪切熔化，并在剪切停止后让亚稳态熔体凝固。使用时间分辨散射技术监测结晶动力学：在低粒子数密度n时，我们应用了一种改进的静态光散射方法，而在大粒子浓度下，首次应用了超小角x射线散射。我们的结果显示了一些意想不到的行为：与均匀体相成核相比，容器壁处的非均匀成核被延迟，并且其速率密度出人意料地略小，这表明了所观察到的结晶过程的复杂性。
