0000000000245853
AUTHOR
W. Van Megen
Crystallization of hard-sphere colloids -- deviations from classical nucleation theory
The creation of three-dimensional ordered colloidal crystals, for application in a range of nanotechnologies, has been a goal for many researchers in the past few years. The main difficulty in creating macroscopic sized crystals of densely packed colloidal particles is that colloidal particles always have a range of particle sizes - ie, they are polydisperse. This paper studied the crystallization kinetics of a hard-sphere colloid with a well defined Gaussian polydispersity. The authors find that crystallization occurs in two stages, and does not follow the simple classical nucleation picture. The paper discusses the implications of these results for research into colloidal crystals as poss…
Measurement of the self-intermediate scattering function of suspensions of hard spherical particles near the glass transition
Dynamic light-scattering measurements are reported for suspensions at concentrations in the vicinity of the glass transition. In a mixture of identically sized but optically different particles having hard-sphere-like interactions, we project out the incoherent (or self-) intermediate scattering functions by adjusting the refractive index of the suspending liquid until scattering from the structure is suppressed. Due to polydispersity, crystallization is sufficiently slow so that good estimates of ensemble-averaged quantities can be measured for the metastable fluid states. Crystallization of the suspensions is still exploited, however, to set the volume fraction scale in terms of effective…
Dynamics of crystallization in hard-sphere suspensions.
Density fluctuations are monitored by small-angle light scattering during the crystallization of 0.22-\ensuremath{\mu}m-radius, hard colloidal spheres. Measured structure factors show an intensity maximum at finite-scattering vectors. The shape of the intensity distribution scales at early times during nucleation and growth and again at large times during ripening. At intermediate times there is a crossover region where scaling ceases to be valid. Both the amplitude and the position of the maximum intensity show quasi-power law behavior in time. The values of the observed exponents are within the range expected for classical growth models. The breadth of the intensity distribution increases…