¹Department of Physics and Engineering Physics, Central Connecticut State University,
1615 Stanley str., New Britain, CT 06050 USA
¹Institute of Experimental Physics, Slovak Academy of Sciences
47, Watsonova str., 04001 Košice, Slovakia
E-mail: kopcan@saske.sk
¹Institute of Physics, NAS of Ukraine, 46, prospect Nauky, 03680 Kyiv, Ukraine
¹Kyiv National University of Technologies and Design,
2, Nemirovich-Danchenko str., 01011 Kyiv, Ukraine
¹V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine
41, prospect Nauky, 03680 Kyiv, Ukraine
*Corresponding author e-mail: akoval@knutd.com.ua

Abstract. In this paper, the effects of SOR5, SOR10, and SOR15 nanoimpurities on the value of the ionic conductivity of the homeotropically aligned nematic liquid crystal 6CB are reported. Electrical measurements are carried out within a wide frequency range (from 6 Hz to 106 Hz) at room temperature (293 K). The largest changes in the electrical conductivity occur in the low-frequency range (less than 103 Hz) and depend on the type of nanoimpurity and on its concentration. Despite the similarity in the chemical composition of SOR5, SOR10, and SOR15, the measured dependences of the electrical conductivity of the studied samples on the concentration of nanoimpurities are substantially different. In the case of the SOR10 impurity, the ionic component of the electrical conductivity depends on the concentration of SOR10 according to a power law with an exponent approximately equal to 0.5, which is typical for the bimolecular recombination of charge carriers (i.e., the behavior of a weak electrolyte). Liquid crystal samples containing SOR5 and SOR15 nanoimpurities behave in a similar way in a low concentration region (between 0.01 and 0.05 mass %). Interestingly, further increase in the concentration of nanodopants (>0.05 mass %) results in a dramatically different behavior. The electrical conductivity of liquid crystals doped with SOR5 undergoes a sharp increase whereas the electrical conductivity of samples containing SOR15 decreases.

Keywords:dielectric properties, nematic liquid crystal, homeotropic alignment of molecules, ionic conductivity, nanoimpurity concentration.

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