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

Abstract

X-ray measurements on single-crystals of ${\mathrm{Rb}}_{1\ensuremath{-}x}{({\mathrm{NH}}_{4})}_{x}{\mathrm{H}}_{2}{\mathrm{PO}}_{4}$ 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.