The aging of a charged colloidal system has been studied by small-angle x-ray scattering, in the exchanged momentum range $Q=0.03–5{\mathrm{nm}}^{-1}$, and by dynamic light scattering, at different clay concentrations $(C_w=0.6–2.8\%)$. The static structure factor $S\left(Q\right)$ has been determined as a function of both aging time and concentration. This is the direct experimental evidence of the existence and evolution with aging time of two different arrested states in a single system simply obtained only by changing its volume fraction: an inhomogeneous state is reached at low concentrations, while a homogeneous one is found at high concentrations.

• Received 28 June 2007

DOI:https://doi.org/10.1103/PhysRevE.77.020402