Low frequency dielectric relaxation, spontaneous polarization, optical tilt angle and response time investigations in a flourinated ferroelectric liquid crystal, N125F2(R*)

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

Research output: Chapter in Book/Report/Conference proceedingChapter

10 Citations (Scopus)

Abstract

Experimental investigations of thermal microscopy, low frequency dielectric relaxation, spontaneous polarization P s (T), optical tilt angleθ(T) and response timesτ s (T) are carried out in a fluorinated ferroelectric liquid crystal, N125F2(R) exhibiting smectic-A and smectic-Cphases. Dielectric loss in the smectic-A phase exhibits single Debye's relaxation in the MHz region. The smectic-Cphase exhibits two relaxations, viz., a Goldstone mode at500 Hz and another at a much higher frequency,5 MHz. The Arrhenius shift of Smectic-A relaxation frequency (f R ) gives an activation energy of 1.5 eV. The influence of temperature and applied voltage on the smectic-CGoldstone mode relaxation is studied. In the smectic-Chigh frequency relaxation mode, the relaxation frequency (relevant to the tilt) is found to increase with decreasing temperature. The temperature variation of the reciprocal of the dielectric strength (1/Δ s ) above the smectic-A - smectic-Cphase transition qualitatively supports the Curie-Weiss law. Temperature variation of primary (tilt) and secondary (P s ) order parameters are presented. The temperature variation ofτ s in the smectic-Cphase studied through square wave technique is presented. The influence of fluorine atoms on the rigid core part of the present ferroelectric liquid crystal on the physical properties exhibited in it's smectic-Cphase is discussed.

Original languageEnglish
Title of host publicationFerroelectrics
Pages79-93
Number of pages15
Volume300
DOIs
Publication statusPublished - Jan 1 2004

Fingerprint

Liquid Crystals
optical polarization
Dielectric relaxation
Light polarization
Liquid crystals
Ferroelectric materials
liquid crystals
low frequencies
Temperature
Fluorine
temperature
Dielectric losses
Curie-Weiss law
Microscopic examination
square waves
Activation energy
Physical properties
dielectric loss
Polarization
fluorine

Keywords

  • Dielectric relaxation
  • Ferroelectric liquid crystals
  • Goldstone and soft modes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

Cite this

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title = "Low frequency dielectric relaxation, spontaneous polarization, optical tilt angle and response time investigations in a flourinated ferroelectric liquid crystal, N125F2(R*)",
abstract = "Experimental investigations of thermal microscopy, low frequency dielectric relaxation, spontaneous polarization P s (T), optical tilt angleθ(T) and response timesτ s (T) are carried out in a fluorinated ferroelectric liquid crystal, N125F2(R) exhibiting smectic-A and smectic-Cphases. Dielectric loss in the smectic-A phase exhibits single Debye's relaxation in the MHz region. The smectic-Cphase exhibits two relaxations, viz., a Goldstone mode at500 Hz and another at a much higher frequency,5 MHz. The Arrhenius shift of Smectic-A relaxation frequency (f R ) gives an activation energy of 1.5 eV. The influence of temperature and applied voltage on the smectic-CGoldstone mode relaxation is studied. In the smectic-Chigh frequency relaxation mode, the relaxation frequency (relevant to the tilt) is found to increase with decreasing temperature. The temperature variation of the reciprocal of the dielectric strength (1/Δ s ) above the smectic-A - smectic-Cphase transition qualitatively supports the Curie-Weiss law. Temperature variation of primary (tilt) and secondary (P s ) order parameters are presented. The temperature variation ofτ s in the smectic-Cphase studied through square wave technique is presented. The influence of fluorine atoms on the rigid core part of the present ferroelectric liquid crystal on the physical properties exhibited in it's smectic-Cphase is discussed.",
keywords = "Dielectric relaxation, Ferroelectric liquid crystals, Goldstone and soft modes",
author = "Potukuchi, {D. M.} and George, {A. K.} and C. Carboni and Al-Harthi, {S. H.} and J. Naciri",
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T1 - Low frequency dielectric relaxation, spontaneous polarization, optical tilt angle and response time investigations in a flourinated ferroelectric liquid crystal, N125F2(R*)

AU - Potukuchi, D. M.

AU - George, A. K.

AU - Carboni, C.

AU - Al-Harthi, S. H.

AU - Naciri, J.

PY - 2004/1/1

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N2 - Experimental investigations of thermal microscopy, low frequency dielectric relaxation, spontaneous polarization P s (T), optical tilt angleθ(T) and response timesτ s (T) are carried out in a fluorinated ferroelectric liquid crystal, N125F2(R) exhibiting smectic-A and smectic-Cphases. Dielectric loss in the smectic-A phase exhibits single Debye's relaxation in the MHz region. The smectic-Cphase exhibits two relaxations, viz., a Goldstone mode at500 Hz and another at a much higher frequency,5 MHz. The Arrhenius shift of Smectic-A relaxation frequency (f R ) gives an activation energy of 1.5 eV. The influence of temperature and applied voltage on the smectic-CGoldstone mode relaxation is studied. In the smectic-Chigh frequency relaxation mode, the relaxation frequency (relevant to the tilt) is found to increase with decreasing temperature. The temperature variation of the reciprocal of the dielectric strength (1/Δ s ) above the smectic-A - smectic-Cphase transition qualitatively supports the Curie-Weiss law. Temperature variation of primary (tilt) and secondary (P s ) order parameters are presented. The temperature variation ofτ s in the smectic-Cphase studied through square wave technique is presented. The influence of fluorine atoms on the rigid core part of the present ferroelectric liquid crystal on the physical properties exhibited in it's smectic-Cphase is discussed.

AB - Experimental investigations of thermal microscopy, low frequency dielectric relaxation, spontaneous polarization P s (T), optical tilt angleθ(T) and response timesτ s (T) are carried out in a fluorinated ferroelectric liquid crystal, N125F2(R) exhibiting smectic-A and smectic-Cphases. Dielectric loss in the smectic-A phase exhibits single Debye's relaxation in the MHz region. The smectic-Cphase exhibits two relaxations, viz., a Goldstone mode at500 Hz and another at a much higher frequency,5 MHz. The Arrhenius shift of Smectic-A relaxation frequency (f R ) gives an activation energy of 1.5 eV. The influence of temperature and applied voltage on the smectic-CGoldstone mode relaxation is studied. In the smectic-Chigh frequency relaxation mode, the relaxation frequency (relevant to the tilt) is found to increase with decreasing temperature. The temperature variation of the reciprocal of the dielectric strength (1/Δ s ) above the smectic-A - smectic-Cphase transition qualitatively supports the Curie-Weiss law. Temperature variation of primary (tilt) and secondary (P s ) order parameters are presented. The temperature variation ofτ s in the smectic-Cphase studied through square wave technique is presented. The influence of fluorine atoms on the rigid core part of the present ferroelectric liquid crystal on the physical properties exhibited in it's smectic-Cphase is discussed.

KW - Dielectric relaxation

KW - Ferroelectric liquid crystals

KW - Goldstone and soft modes

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