Short-range ordering and freezing in a randomly mixed ferroelectric-antiferroelectric crystal

Abstract

X-ray measurements on single-crystals of ${\mathrm{Rb}}_{1-x}{\left({\mathrm{NH}}_4\right)}_x{\mathrm{H}}_2{\mathrm{PO}}_4$ trace the development of a glasslike state. The absence of macroscopic crystal-symmetry change during freezing is confirmed, while diffuse scattering reveals the growth of very-short-range order. The latter coincides with a compressibility anomaly seen in Brillouin scattering and with dielectric effects suggesting freezing. The system is in many ways analogous to spin-glasses.