Impedance spectroscopy and dielectric anisotropy-type analysis in dye-doped nematic liquid crystals having different preliminary orientations

Okutan M., Yakuphanoglu F., San S. E., Koysal O.

PHYSICA B-CONDENSED MATTER, vol.368, pp.308-317, 2005 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 368
  • Publication Date: 2005
  • Doi Number: 10.1016/j.physb.2005.07.029
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.308-317
  • Keywords: liquid crystals, dielectric anisotropy, homogeneous, homeotropic, molecular reorientation, MOLECULAR-REORIENTATION, DIFFRACTION
  • Kocaeli University Affiliated: Yes


Reorientation tendencies of liquid crystal (LC) molecules are investigated for two different fundamental orientation configurations known as homogeneous (HG) and homeotropic (HT). Dielectric anisotropy properties of a HT sample and a HG one are investigated as a function of frequency. The dielectric anisotropy changes from the positive type to the negative type. The obtained results suggest that the samples exhibit dielectrically controlled positive dielectric anisotropy (p-type Delta epsilon) with a critical frequency transition to negative dielectric anisotropy (n-type Delta epsilon) behavior. The high-frequency relaxation process exhibits non-Debye-type behavior due to dipolar rotation around the long molecular axis. The orientation configurations (HG and HT) change the dielectric anisotropy properties of the LC in a favorable manner. (c) 2005 Elsevier B.V. All rights reserved.