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DF: Dielektrische Festkörper
DF 9: Phasenüberg
änge und Spektroskopie
DF 9.7: Talk
Tuesday, March 8, 2005, 12:20–12:40, TU EMH225
Dielectric spectroscopy of CuInP2(SxSe1−x)6 ( with x=0.4-0.95) layered crystals — •Juras Banys1, Jan Macutkevic1, Robertas Grigalaitis1, Algirdas Brilingas1, and Julian Vysochanskii2 — 1Departament of Radiophysics, Faculty of Physics, Vilnius University, Lithuania — 2Institute of Solid State Physics and Chemistry of Uzhgorod University, Ukraine
The complex dielectric response of CuInP2(SxSe1−x)6 crystals were investigated in the frequency range 20 Hz to 1.2 GHz. At low frequencies and high temperatures the dielectric spectra is mainly caused by high ionic conductivity. At higher frequencies and lower temperatures the dielectric spectra is caused by a broad distribution of relaxation times. The maximum of real and imaginary parts of dielectric permittivity shifts to the higher temperatures with increasing frequency. Obtained dielectric spectra were fitted with Cole-Cole formula and the mean relaxation time has been obtained. On cooling the Cole-Cole mean relaxation time strongly increase and distribution of relaxation times broaden. The temperature dependence of mean relaxation time was fitted with Fogel-Vulcher law. All features of the dielectric dispersion at low temperatures of present crystals are typical for the dipolar glasses. In the crystals with sulfur concentration x=0.95 ferroelectric phase transition has been observed together with the glass state at low temperatures.