E.P.R, X-rays and 10 Ghz-dielectric measurements in Rb2ZnCI4near the incommensurate-commensurate ferroelectric phase transition

We report the results of comparative studies on the incommensurate-commensurate phase change in Rb2ZnCl4using local measurements by E.P.R, Bragg scattering and dielectric losses measurements at 10 GHz. The later measurements are achieved using the E.P.R spectrometer with a particular design of the resonant cavity. The specific role of substitutional impurities (Mn2+, Cu2+, K+) is analysed from these studies.