THE PHASE-DIAGRAM OF (NH4I)(X)(KI)(1-X)

The x, T phase diagram of(NH4I)(x)(KI)(1-x) has been determined using neutron diffraction experiments and dielectric spectroscopy. At low te mperatures and with decreasing x, the sequence gamma, beta, epsilon an d glass phase has been detected. The critical concentration x(c) appro ximate to 0.55 separates the glassy phase with frozen-in orientational disorder from the epsilon phase which reveals long-range orientationa l order. Close to x(c) our experiments reveal evidence for two subsequ ent glass transitions.