Semiconductor Physics, Quantum Electronics & Optoelectronics, 21 (4), P. 397-401 (2018).

Influence of Li-TCNQ impurities on dielectric properties of planar-oriented nematic liquid crystal
V.E. Vovk1, O.V. Kovalchuk1,2,3, T.M. Kovalchuk4

1Institute of Physics, National Academy of Sciences of Ukraine, 46, prospect Nauky, 03680 Kyiv, Ukraine
2Kyiv National University of Technologies and Design, 2, Nemirovich-Danchenko str., 01011 Kyiv, Ukraine E-mail:
3National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute” 37, prospect Peremohy, 03056 Kyiv, Ukraine
4V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, 41, prospect Nauky, 03680 Kyiv, Ukraine

Abstract. The dielectric properties of planar-oriented nematic liquid crystal E25M with Li-TCNQ impurities have been investigated within the frequency range 10 –1 ...10 6 Hz and temperatures 298...343 K. The concentration of impurities varied between 0 and 0.1 wt.%. It has been shown that the presence of a small impurity of Li-TCNQ in liquid crystal increases electrical conductivity, influences the value of the conductivity activation energy in the nematic phase and practically does not change the activation energy in the isotropic phase. The times of dielectric relaxation τ for the low-frequency part of the spectrum of complex dielectric constant components have been estimated. It has been shown that, within the frame of existence of the liquid crystal phase, the temperature dependence of τ –1 linearly depends on the inverse value of the temperature in the Arrhenius coordinates and is well agreed with the temperature dependence of conductivity.

Keywords: dielectric spectroscopy, nematic liquid crystal, Li-TCNQ impurity, activation energy.

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