Resonant phenomena in colloidal crystals

Abstract

Ahstmct: Colloidal crystals of completely deionized suspensions of latex speres are subjected to oscillatory and steady shear, as well as to homogeneous and inhomogeneous electric fields. Various resonant phenomena observed in such experiments are reported. Under very slow dc-flow (v, < 7 pm s-I) the crystalline solid moves with a plug-like velocity profile, and it is excited to resonances of vp3 = 7 Hz by alternating stick-slip at the walls of stick-slip frequency v,, = 3.5 Hz. At slightly faster Flow (v,[7][8][9][10][11][12] there is depinning at all walls and the crystal moves without vibrationaI excitation, whereas increasing the flow further, results in, first, grinding of the soIid into fine crystallites, and then, shear melting and a parabolic velocity profile [I, 61.

Crystallization kinetics of repulsive colloidal spheres

“…For the particle discussed here in more detail figure 17(a) and (b) give the phase diagrams [44,48]. At low density and low salt the suspension is more OCP-like and a bcc structure is formed while for the more HS-like case with stronger screening an fcc structure is observed.…”

“…Colloid specific length scales are of the order of the wavelength of visible light and thus allow for access via microscopy and light scattering yielding complementary information from real and reciprocal space [7,8,44]. For Brownian dynamics the typical time for a noninteracting particle to diffuse the distance of its own radius a is in the millisecond range and may be calculated from the Stokes-Einstein diffusion coefficient D 0 = k B T /6πηa, where η is the shear viscosity.…”