The analysis of temperature effect on frequency dependent dielectric parameters of semifluorinated liquid crystalline biphenyl carboxylic acid


Karanlık G. , Yıldız A., Canli N. , Ocak H. , Okutan M. , Eran B.

Physica B: Condensed Matter, vol.555, pp.85-90, 2019 (Journal Indexed in SCI Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 555
  • Publication Date: 2019
  • Doi Number: 10.1016/j.physb.2018.10.037
  • Title of Journal : Physica B: Condensed Matter
  • Page Numbers: pp.85-90
  • Keywords: Impedance spectroscopy (IS), Liquid crystal, Phase transition temperature

Abstract

© 2018 Elsevier B.V.In this study, the dielectric properties of the liquid crystal 4–(7,7,8,8,9,9,10,10,10–nonafluorodecyloxy)biphenyl–4′–carboxylic acid (NBCA) exhibiting a Smectic C mesophase have been analyzed. NBCA has two critical temperatures which are 194 °C for the crystal phase to the smectic phase transition, and 269 °C for the smectic phase to the isotropic phase transition. Impedance spectroscopy measurements were made at regular intervals at different temperatures which includes these transitions. By using capacitance method, the complex dielectric constants have been calculated for each temperature, and the real part of dielectric constants have been fitted to the Cole-Cole equation. In addition, ac conductivity mechanisms of the NBCA at different temperatures and different phases and also activation energies which belongs to some selected frequencies have been determined by the imaginary part of dielectric constants.