Tata BV, Boda D, Henderson D, Nikolov A, Wasan DT
Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu, India.
Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 2000 Sep;62(3 Pt B):3875-81. doi: 10.1103/physreve.62.3875.
Monte Carlo simulations have been performed to study the influence of a wedge confinement by hard walls on the ordering of charged colloidal particles interacting through screened Coulomb repulsive potential in an aqueous medium. The density distribution of particles for a fixed wedge angle straight theta(0) is studied for different suspension parameters, viz., bulk volume fraction straight phi, salt concentration C(s), and charge Ze on the particles. The density distribution rho(straight theta) along the angular direction and that along the radial direction, rho(r), have been analyzed in different regions of the wedge. Simulations show the formation of layered structure along the angular direction and a large gathering of particles along the wall. The number of layers as well as the density of particles within the layer are found to change as the strength and range of the interaction are varied, whereas the density profiles calculated close to the vertex region showed no significant variation in the density. The radial density profiles rho(r) corresponding to the vertex region show one-dimensional (1D) ordering of particles parallel to the vertex at a distance that is close to a wedge height, h equal to diameter of the particle. This 1D ordering is found to be destroyed upon the addition of salt or lowering the straight phi. The reported experimental observations on the "vacuum phase" are discussed in the light of the present results.
已进行蒙特卡罗模拟，以研究硬壁楔形限制对水介质中通过屏蔽库仑排斥势相互作用的带电胶体粒子有序排列的影响。针对不同的悬浮参数，即本体体积分数φ、盐浓度Cs和粒子上的电荷Ze，研究了固定楔形角θ0时粒子的密度分布。分析了楔形不同区域沿角向的密度分布ρ(θ)和沿径向的密度分布ρ(r)。模拟结果表明，沿角向形成了层状结构，沿壁面有大量粒子聚集。随着相互作用强度和范围的变化，发现层数以及层内粒子密度会发生变化，而在顶点区域附近计算的密度分布在密度上没有显著变化。对应于顶点区域的径向密度分布ρ(r)显示，在接近楔形高度h（等于粒子直径）处，粒子沿与顶点平行的方向呈现一维（1D）有序排列。发现添加盐或降低φ会破坏这种1D有序排列。根据当前结果讨论了关于“真空相”的已报道实验观察结果。
