DIELECTRIC-DISPERSION IN PURE AND DOPED LITHIUM RUBIDIUM SULFATE

The frequency (10(2)-10(5) Hz) dependence of the dielectric properties of lithium rubidium sulphate (LRS) are reported in the vicinity of th e transition temperature T-c = 477 K. The a.c. conductivity sigma(omeg a) shows a strong temperature dependence and weak frequency response. The dielectric constant in this region shows a strong frequency disper sion. A Cole-Cole diagram was used to determine the distribution param eter and the molecular relaxation time. The effect of doping with Dy+3 , Sm+3 and V+3, was also studied. It was found that doping gives rise to localized states which produce a disorder in the structure of LiRbS O4.