Synthesis and characterization of bent liquid crystal phases by microscopy, calorimetry, spontaneous polarization and low-frequency dielectric relaxation studies in Bent-7

V. C. Pallavajhula, M. Srinivasulu, V. G.K.M. Pisipati, D. M. Potukuchi

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Synthesis of the bent-shaped (or -shaped) achiral liquid crystal Bent 7, viz., 1,3-phenylene bis(4-heptyloxy benzoate) with resorcinol as central moiety is reported. Supra molecular formation is confirmed by KBr solid state IR spectra. Polarized Thermal Microscopy(TM), Differential Scanning Calorimetry (DSC) and Spontaneous Polarization(PS) experiments infer a bivariant monotropic (cooling), phase sequence viz., Isotropic →B2(FE) → B5(AF) solid. Phase transition temperatures determined from temperature variation of Dielectric Constant (or relative permittivity εr (T)) agree with TM and DSC. Dielectric dispersion reveals different re-orientation processes viz., a slow (LF ∼ 1 kHZ) and a fast (HF ∼ 1 MHz) one in both the B2 and B5 phases. Both the relaxations in B5(AF) phase follow Arrhenius shift to infer 1.12 and 0.89 eV of activation energies, respectively. Off-centred dispersion studied through the Cole-Cole plots in B5(AF) phase infer the increasing trend of dielectric increment δε and distribution parameter with decreasing temperature. Trends of δε and α-parameter suggest a greater fall of response width during slow reorientation and a relative freezing rate during fast reorientation.

Original languageEnglish
Pages (from-to)45-64
Number of pages20
JournalFerroelectrics
Volume361
Issue number1
DOIs
Publication statusPublished - 01-12-2007

Fingerprint

Liquid Crystals
Dielectric relaxation
Calorimetry
Liquid crystals
retraining
Microscopic examination
Permittivity
heat measurement
liquid crystals
Polarization
low frequencies
microscopy
Differential scanning calorimetry
polarization
synthesis
permittivity
trends
scanning
Benzoates
Freezing

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

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title = "Synthesis and characterization of bent liquid crystal phases by microscopy, calorimetry, spontaneous polarization and low-frequency dielectric relaxation studies in Bent-7",
abstract = "Synthesis of the bent-shaped (or -shaped) achiral liquid crystal Bent 7, viz., 1,3-phenylene bis(4-heptyloxy benzoate) with resorcinol as central moiety is reported. Supra molecular formation is confirmed by KBr solid state IR spectra. Polarized Thermal Microscopy(TM), Differential Scanning Calorimetry (DSC) and Spontaneous Polarization(PS) experiments infer a bivariant monotropic (cooling), phase sequence viz., Isotropic →B2(FE) → B5(AF) solid. Phase transition temperatures determined from temperature variation of Dielectric Constant (or relative permittivity εr (T)) agree with TM and DSC. Dielectric dispersion reveals different re-orientation processes viz., a slow (LF ∼ 1 kHZ) and a fast (HF ∼ 1 MHz) one in both the B2 and B5 phases. Both the relaxations in B5(AF) phase follow Arrhenius shift to infer 1.12 and 0.89 eV of activation energies, respectively. Off-centred dispersion studied through the Cole-Cole plots in B5(AF) phase infer the increasing trend of dielectric increment δε and distribution parameter with decreasing temperature. Trends of δε and α-parameter suggest a greater fall of response width during slow reorientation and a relative freezing rate during fast reorientation.",
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Synthesis and characterization of bent liquid crystal phases by microscopy, calorimetry, spontaneous polarization and low-frequency dielectric relaxation studies in Bent-7. / Pallavajhula, V. C.; Srinivasulu, M.; Pisipati, V. G.K.M.; Potukuchi, D. M.

In: Ferroelectrics, Vol. 361, No. 1, 01.12.2007, p. 45-64.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Synthesis and characterization of bent liquid crystal phases by microscopy, calorimetry, spontaneous polarization and low-frequency dielectric relaxation studies in Bent-7

AU - Pallavajhula, V. C.

AU - Srinivasulu, M.

AU - Pisipati, V. G.K.M.

AU - Potukuchi, D. M.

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AB - Synthesis of the bent-shaped (or -shaped) achiral liquid crystal Bent 7, viz., 1,3-phenylene bis(4-heptyloxy benzoate) with resorcinol as central moiety is reported. Supra molecular formation is confirmed by KBr solid state IR spectra. Polarized Thermal Microscopy(TM), Differential Scanning Calorimetry (DSC) and Spontaneous Polarization(PS) experiments infer a bivariant monotropic (cooling), phase sequence viz., Isotropic →B2(FE) → B5(AF) solid. Phase transition temperatures determined from temperature variation of Dielectric Constant (or relative permittivity εr (T)) agree with TM and DSC. Dielectric dispersion reveals different re-orientation processes viz., a slow (LF ∼ 1 kHZ) and a fast (HF ∼ 1 MHz) one in both the B2 and B5 phases. Both the relaxations in B5(AF) phase follow Arrhenius shift to infer 1.12 and 0.89 eV of activation energies, respectively. Off-centred dispersion studied through the Cole-Cole plots in B5(AF) phase infer the increasing trend of dielectric increment δε and distribution parameter with decreasing temperature. Trends of δε and α-parameter suggest a greater fall of response width during slow reorientation and a relative freezing rate during fast reorientation.

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