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    Temperature dependency of impedance spectroscopy behaviors in side-chain liquid crystalline polymer
    (Elsevier, 2009) Okutan, M.; Koysal, O.; San, S. E.; Senturk, E.
    In this paper, the electrical properties of side-chain liquid crystalline polymer (SLCP) are investigated by impedance spectroscopy technique. We report the measurement of dielectric and conductivity for SLCP from 1 kHz to 10 MHz within the temperature range from 300 to 370 K. The DC conductivity obeys Arrhenius law and it gives a small deviation at 315 K. The activation energies are equal to 0.20 eV and 0.75 eV for high and low temperatures, respectively. The frequency dependence of conductivity satisfies the power law, sigma(AC) = Aw(5), with s = 0.50-0.57. The evaluated power law exponent s exhibits nearly linear decreasing behavior with temperature. This suggests that the Correlated Barrier Hopping (CBH) model is the operating mechanism. (C) 2009 Elsevier B.V. All rights reserved.
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    The electrical properties of a fullerene and CI Acid Red 2 (methyl red) doped E7 nematic liquid crystal
    (Elsevier Sci Ltd, 2010) Okutan, M.; San, S. E.; Koysal, O.; Senturk, E.
    The electrical properties of a C.I. Acid Red 2 (4-dimethylaminoazobenzene-2'-carboxylic acid) and fullerene mixture of the nematic liquid crystal E7 were studied using complex dielectric spectroscopy as a function of the frequency of the applied AC-DC signal at various temperatures. Both the real and imaginary components of the dielectric constant decreased with increased frequency of the applied field whilst the AC conductivity increased with increasing frequency of the applied field. The alternating current conductivity sigma(omega) varied with angular frequency, omega as omega(s), with s <= 1, suggesting that a dominant hopping conduction process operated. The temperature dependence of both the AC conductivity and the exponents can be reasonably well interpreted using a correlated barrier hopping model. (C) 2009 Elsevier Ltd. All rights reserved.