Glass States and Freezing Transition in (NH4I)x(KI)1-x.

Abstract

The glass transition in $({\mathrm{NH}}_{4}\mathrm{I}{)}_{x}(\mathrm{KI}{)}_{1\ensuremath{-}x}$ has been studied using dielectric spectroscopy. The $(x,T)$ phase diagram reveals three different glassy regions, ${g}_{1}$, ${g}_{2}$, and ${g}_{3}$. The dynamical susceptibility in the regime ${g}_{2}$ reveals a power-law dependence on frequency, ${\ensuremath{\epsilon}}^{*}\ensuremath{\propto}A(T){\ensuremath{\omega}}^{s(T)}$. The experimental results are compared with theoretical models and provide evidence for the near-equilibrium dynamics in an orientational glass.