A fresh look at the Laponite phase diagram

By reviewing experimental and theoretical works, we discuss the phase diagram of Laponite suspensions, with the aim of clarifying several issues that have caused a long-time controversy on the system. We claim that, if aging and sample preparation are correctly taken into account, a unifying picture emerges from different experimental studies. Multiple non-ergodic states are identified, including a low concentration equilibrium gel and a high concentration Wigner glass in the absence of salt. These findings are critically discussed also with respect to recent evidence of phase separation at extremely low densities and to existing theoretical and numerical works.