Drude-type conductivity of charged sphere colloidal crystals: density and temperature dependence.
Drude-type conductivity of charged sphere colloidal crystals: density and temperature dependence.
复制标题
带电球体胶体晶体的德鲁德型电导率：密度和温度依赖性。
作者：
M. Medebach;R. C. Jordán;H. Reiber;H. Schöpe;R. Biehl;M. Evers;D. Hessinger;J. Oláh;T. Palberg;E. Schönberger;P. Wette
我们报告广泛的测量低频极限的胶体流体和晶体形成的带电胶体球悬浮在去离子水中的交流电导率。温度在5 ° C < Theta < 35 ° C的范围内变化，对于较大的颗粒，颗粒数密度n在0.2和25 μ m（-3）之间，对于两种研究物种中较小的颗粒，颗粒数密度n分别为2.75和210 μ m（-3）。在固定的θ，电导率随n的增加而线性增加，而在流体-固相边界没有任何显着的变化。在固定的n，它增加了增加θ和增加是更明显的较大的n。缺乏一个严格的电流体动力学处理抗衡离子为主的系统，我们描述了我们的数据与一个简单的模型有关的Drude的金属导电性理论。关键参数是有效传输的粒子电荷或价态Z（*）。除了Z（*）的温度依赖性之外，所有温度依赖性均取自文献。在实验分辨率Z（*）被发现是独立的n无关的悬浮液结构。有趣的是，Z（*）随温度降低，与数值计算接近定量一致。
We report on extensive measurements in the low-frequency limit of the ac conductivity of colloidal fluids and crystals formed from charged colloidal spheres suspended in de-ionized water. Temperature was varied in a range of 5 degrees C < Theta < 35 degrees C and the particle number density n between 0.2 and 25 microm(-3) for the larger, respectively, 2.75 and 210 microm(-3) for the smaller of two investigated species. At fixed Theta the conductivity increased linearly with increasing n without any significant change at the fluid-solid phase boundary. At fixed n it increased with increasing Theta and the increase was more pronounced for larger n. Lacking a rigorous electrohydrodynamic treatment for counterion-dominated systems we describe our data with a simple model relating to Drude's theory of metal conductivity. The key parameter is an effectively transported particle charge or valence Z(*). All temperature dependencies other than that of Z(*) were taken from literature. Within experimental resolution Z(*) was found to be independent of n irrespective of the suspension structure. Interestingly, Z(*) decreases with temperature in near quantitative agreement with numerical calculations.