Dielectric response in the Smectic A and Smectic C* phases of a ferroelectric liquid crystal, 12CN5(R*)

A. K. George, Mariam Al-Hinai, C. Carboni, S. H. Al-Harthi, D. M. Potukuchi, J. Naciri

Research output: Contribution to journalArticle

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Abstract

This paper reports the results of the dielectric relaxation studies performed in the Smectic A (SmA) and Smectic C* (SmC*) phases of the ferroelectric liquid crystal, 12CN5(R*) in the frequency range 5Hz to 13MHz. Planar orientation used throughout the study was achieved by rubbed polyamide coating on the surfaces of the dielectric cell. Transition temperatures determined from the derivative of this dielectric permittivity agrees with that obtained using thermal polarizing microscopy. The dielectric spectrum in the SmA phase shows single relaxation, whereas the SmC* phase has two relaxations, viz., the low frequency Goldstone mode and the high frequency soft mode. Special attention was paid to the study of the low frequency Goldstone mode relaxation. From the Cole-Cole plots, the temperature dependence of dielectric strength (Δε), the relaxation frequency (fR) and the distribution parameter (x) ralevant to the Goldstone mode have been estimated. The relaxation frequency follows the Arrhanius relation in the asymptotic regions far from the transition. Results of the bias-dependent dielectric, measurements of the Goldstone made relaxation, have also been presented.

Original languageEnglish
Pages (from-to)343-353
Number of pages11
JournalMolecular Crystals and Liquid Crystals
Volume409
DOIs
Publication statusPublished - 2004

Fingerprint

Liquid Crystals
Liquid crystals
Ferroelectric materials
liquid crystals
Dielectric relaxation
Nylons
Polyamides
low frequencies
Superconducting transition temperature
Microscopic examination
Permittivity
Derivatives
Coatings
plots
frequency ranges
transition temperature
permittivity
microscopy
coatings
temperature dependence

Keywords

  • Arrhenius plots
  • Cole-cola plots
  • Dielectric relaxation frequency
  • Ferroelectric liquid crystals
  • Goldstone and soft mode

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Dielectric response in the Smectic A and Smectic C* phases of a ferroelectric liquid crystal, 12CN5(R*). / George, A. K.; Al-Hinai, Mariam; Carboni, C.; Al-Harthi, S. H.; Potukuchi, D. M.; Naciri, J.

In: Molecular Crystals and Liquid Crystals, Vol. 409, 2004, p. 343-353.

Research output: Contribution to journalArticle

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AU - George, A. K.

AU - Al-Hinai, Mariam

AU - Carboni, C.

AU - Al-Harthi, S. H.

AU - Potukuchi, D. M.

AU - Naciri, J.

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N2 - This paper reports the results of the dielectric relaxation studies performed in the Smectic A (SmA) and Smectic C* (SmC*) phases of the ferroelectric liquid crystal, 12CN5(R*) in the frequency range 5Hz to 13MHz. Planar orientation used throughout the study was achieved by rubbed polyamide coating on the surfaces of the dielectric cell. Transition temperatures determined from the derivative of this dielectric permittivity agrees with that obtained using thermal polarizing microscopy. The dielectric spectrum in the SmA phase shows single relaxation, whereas the SmC* phase has two relaxations, viz., the low frequency Goldstone mode and the high frequency soft mode. Special attention was paid to the study of the low frequency Goldstone mode relaxation. From the Cole-Cole plots, the temperature dependence of dielectric strength (Δε), the relaxation frequency (fR) and the distribution parameter (x) ralevant to the Goldstone mode have been estimated. The relaxation frequency follows the Arrhanius relation in the asymptotic regions far from the transition. Results of the bias-dependent dielectric, measurements of the Goldstone made relaxation, have also been presented.

AB - This paper reports the results of the dielectric relaxation studies performed in the Smectic A (SmA) and Smectic C* (SmC*) phases of the ferroelectric liquid crystal, 12CN5(R*) in the frequency range 5Hz to 13MHz. Planar orientation used throughout the study was achieved by rubbed polyamide coating on the surfaces of the dielectric cell. Transition temperatures determined from the derivative of this dielectric permittivity agrees with that obtained using thermal polarizing microscopy. The dielectric spectrum in the SmA phase shows single relaxation, whereas the SmC* phase has two relaxations, viz., the low frequency Goldstone mode and the high frequency soft mode. Special attention was paid to the study of the low frequency Goldstone mode relaxation. From the Cole-Cole plots, the temperature dependence of dielectric strength (Δε), the relaxation frequency (fR) and the distribution parameter (x) ralevant to the Goldstone mode have been estimated. The relaxation frequency follows the Arrhanius relation in the asymptotic regions far from the transition. Results of the bias-dependent dielectric, measurements of the Goldstone made relaxation, have also been presented.

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KW - Cole-cola plots

KW - Dielectric relaxation frequency

KW - Ferroelectric liquid crystals

KW - Goldstone and soft mode

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