Semiconductor Physics, Quantum Electronics & Optoelectronics, 23 (2), P. 129-135 (2020).

Temperature dependence of dielectric properties of the liquid crystal 6CB with the embedded Ag7GeS5I nanoparticles
S.I. Poberezhets1, O.V. Kovalchuk1,2,3, I.P. Studenyak4, T.M. Kovalchuk5, I.I. Poberezhets6, V. Lacková7, M. Timko7, P. Kopčanský7

1Institute of Physics, NAS of Ukraine 46, prospect Nauky, 03680 Kyiv, Ukraine
2Kyiv National University of Technologies and Design, 2, Nemirovich-Danchenko str., 01011 Kyiv, Ukraine
3National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” 37, prospect Peremohy, 03056 Kyiv, Ukraine
4Uzhhorod National University, Faculty of Physics, 3, Narodna Sq., 88000 Uzhhorod, Ukraine
5V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine 41, prospect Nauky, 03680 Kyiv, Ukraine
6Uman National University of Horticulture 1, Academichna str. 20300 Uman, Cherkasy region, Ukraine
7Institute of Experimental Physics, Slovak Academy of Sciences 47, Watsonova str., 04001 Košice, Slovakia, E-mail:

Abstract. Within the frequency range 10–1–105 Hz under the temperatures 293–295 K, the dielectric properties of a planar-oriented nematic liquid crystal 6CB with the embedded of 0.1% superionic conductor Ag7GeS5I nanoparticles have been investigated. It has been shown that for the whole temperature range, the obtained frequency dependences of the components ε' and ε" composing the complex dielectric function can be separated into 3 sections. The dispersion of ε' and ε" for the lowest frequencies (less than 102 Hz) is described by the Debye equation and is caused by the rotation of the dipole moments of LC molecules under the action of electric field within the angles corresponding to the fluctuations of the order parameter in a thin near-electrode layer. It has been shown that the temperature dependence of the value of inverse relaxation time for such a process is described by straight lines in the Arrhenius coordinates within each mesophase. The activation energies for these dependences have been estimated for each mesophase. It should be noted that within the middle range of frequencies (102–104 Hz), for each temperature, one can separate a section where the magnitude of the conductivity does not depend on the frequency. The conductivity in these sections is equal to the conductivity of LC with the nanoparticles. It has been found that both the value of inverse relaxation time and the value of conductivity change according to the Arrhenius law on the temperature. The activation energies for the temperature dependence of conductivity and the temperature dependence of inverse relaxation time have been estimated, and it has been shown that they are close (for the nematic phase) and equal (for the isotropic phase). In the highest frequency section of the dielectric spectrum (104–105 Hz), the conductivity of the mixture 6CB + 0.1 wt.% Ag7GeS5I changes according to the power law of the frequency. It has been suggested that a sharp increase in the conductivity of 6CB with nanoparticles of the superionic conductor Ag7GeS5I at the concentration 0.1 wt.% was caused by the sharp increase in the electronic component of conductivity through Ag7GeS5I nanoparticles.

Keywords: keydielectric properties, superionic conductor, frequency dependence, temperature dependence, Debye dispersion, relaxation time, activation energy.

Full Text (PDF)

Back to Volume 23 N2

Creative Commons License
This work is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License.