0000000000246803
AUTHOR
Patrick Simon
Evidence for a glassy dynamics in (Rb-NH 4 ) 2 SO 4 mixed compounds
An orientational glass behavior is evidenced in a [Rb0.7(NH4)0.3]2SO4 mixed crystal. Dielectric experiments (1 kHz–250 MHz) performed along the c-axis evidenced a polydispersive relaxation process. Its temperature dependence follows a Vogel-Fulcher law with a freezing temperature of 12 K.
Ferroelectricity and orientational glass behavior in the [Rbx(NH4)1−x]2SO4system
Abstract The ordering in the electric dipole subsystem of the [Rbx(NH4)1−x]22SO4 family is investigated. The microscopic origin of ferroelectricity for x=0 is discussed, and evidences for the existence of orientational glass behavior in highly substituted crystals are presented.
Lattice dynamics of the fluoride scheelite CaZnF4
The lattice dynamics of the fluoride scheelite CaZnF4 have been investigated by means of infrared reflectivity and Raman scattering. The measured phonon modes have been assigned to the various irreducible representations of the point group of the crystal. The phonon dispersion curves, density of states and sound velocities have been calculated within a rigid-ion model based on experimental zone-centre phonons.