Abstract
The ageing dynamics of a charged colloidal system, Laponite suspended in water, have been investigated by photon correlation technique. The samples covered a novel and very wide range of clay concentrations (C w = 0.3–3.1 wt%) and four different NaCl concentrations (C s = 1 × 10−4 M, 1 × 10−3 M, 2 × 10−3 M and 5 × 10−3 M) and were studied to investigate the phase diagram, which has been a subject of discussion in recent literature. A clear picture of the Laponite phase diagram has been obtained. The measurements show the existence of two different dynamical routes to reach a final arrested state and the presence of a transition line between them in the C w−C s plane.