Influence of moieties for the phase stability, spontaneous polarization and dielectric relaxations in an achiral ferroelectric bent liquid crystal, PBUOB

P. V. Chalapathi, M. Srinivasulu, V. G.K.M. Pisipati, Ch Satyanarayana, D. M. Potukuchi

Research output: Contribution to journalArticle

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Abstract

The occurrence of ferroelelectric phases and influence of chemical moieties in the area of supra-molecular achiral Bent core Liquid Crystals (BLCs) are reviewed. Synthesis of an intermediate/higher homolog of PBnOB series (for n=11), PBUOB, viz. 1,3-Phenyline-Bis(4-UndecylOxy Benzoate), is presented. Smectic LC phases exhibited by PBUOB are characterized by Polarized Optical Microscopy (POM), Differential Scanning Calorimetry (DSC) and Spontaneous Polarization (PS) techniques. Observations infer a bi-variant FE LC smectic phase occurrence, viz., isotropic→B2(FE)→B 5(FE)→solid phases in cooling and solid→B 5→isotropic phases in heating scans. Occurrence of B2 phase is monotropic (in cooling), while B5 phase is enantiotropic. IB2 and B2B5 phase transitions are found to be of first order nature. The FE phases possess a moderate PS value of ∼40 nC cm-2. Transition temperatures from dielectric studies agree with those from TM and DSC. Two modes of relaxations are observed, viz., a slow scissor mode at ∼1 kHz and a fast mode at ∼1 MHz. Anisotropic Dipolar Model is proposed to explain the reorientation mechanism. Arrhenius shifts of Relaxation Frequency (fR) show differing activation energies for two modes, i.e., 0.11 and 0.98 eV; 0.25 and 1.18 eV in B 2 and B5 phases, respectively. Temperature variation of dielectric increment Δε and α-parameter LC phases reveals the relative fixture of dipole moment in polar smectic layers. An analytical study for the thermal stability, PS and fR in the FE phases is presented with respect to the constitution and configuration of moieties in BLCs.

Original languageEnglish
Pages (from-to)2081-2090
Number of pages10
JournalPhysica B: Condensed Matter
Volume406
Issue number11
DOIs
Publication statusPublished - 15-05-2011

Fingerprint

Liquid Crystals
Phase stability
Dielectric relaxation
Liquid crystals
Ferroelectric materials
Differential scanning calorimetry
Phenindione
liquid crystals
Polarization
Cooling
Benzoates
Dipole moment
occurrences
polarization
Superconducting transition temperature
Optical microscopy
Thermodynamic stability
heat measurement
Activation energy
Phase transitions

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

Cite this

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title = "Influence of moieties for the phase stability, spontaneous polarization and dielectric relaxations in an achiral ferroelectric bent liquid crystal, PBUOB",
abstract = "The occurrence of ferroelelectric phases and influence of chemical moieties in the area of supra-molecular achiral Bent core Liquid Crystals (BLCs) are reviewed. Synthesis of an intermediate/higher homolog of PBnOB series (for n=11), PBUOB, viz. 1,3-Phenyline-Bis(4-UndecylOxy Benzoate), is presented. Smectic LC phases exhibited by PBUOB are characterized by Polarized Optical Microscopy (POM), Differential Scanning Calorimetry (DSC) and Spontaneous Polarization (PS) techniques. Observations infer a bi-variant FE LC smectic phase occurrence, viz., isotropic→B2(FE)→B 5(FE)→solid phases in cooling and solid→B 5→isotropic phases in heating scans. Occurrence of B2 phase is monotropic (in cooling), while B5 phase is enantiotropic. IB2 and B2B5 phase transitions are found to be of first order nature. The FE phases possess a moderate PS value of ∼40 nC cm-2. Transition temperatures from dielectric studies agree with those from TM and DSC. Two modes of relaxations are observed, viz., a slow scissor mode at ∼1 kHz and a fast mode at ∼1 MHz. Anisotropic Dipolar Model is proposed to explain the reorientation mechanism. Arrhenius shifts of Relaxation Frequency (fR) show differing activation energies for two modes, i.e., 0.11 and 0.98 eV; 0.25 and 1.18 eV in B 2 and B5 phases, respectively. Temperature variation of dielectric increment Δε and α-parameter LC phases reveals the relative fixture of dipole moment in polar smectic layers. An analytical study for the thermal stability, PS and fR in the FE phases is presented with respect to the constitution and configuration of moieties in BLCs.",
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Influence of moieties for the phase stability, spontaneous polarization and dielectric relaxations in an achiral ferroelectric bent liquid crystal, PBUOB. / Chalapathi, P. V.; Srinivasulu, M.; Pisipati, V. G.K.M.; Satyanarayana, Ch; Potukuchi, D. M.

In: Physica B: Condensed Matter, Vol. 406, No. 11, 15.05.2011, p. 2081-2090.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Influence of moieties for the phase stability, spontaneous polarization and dielectric relaxations in an achiral ferroelectric bent liquid crystal, PBUOB

AU - Chalapathi, P. V.

AU - Srinivasulu, M.

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

AU - Satyanarayana, Ch

AU - Potukuchi, D. M.

PY - 2011/5/15

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N2 - The occurrence of ferroelelectric phases and influence of chemical moieties in the area of supra-molecular achiral Bent core Liquid Crystals (BLCs) are reviewed. Synthesis of an intermediate/higher homolog of PBnOB series (for n=11), PBUOB, viz. 1,3-Phenyline-Bis(4-UndecylOxy Benzoate), is presented. Smectic LC phases exhibited by PBUOB are characterized by Polarized Optical Microscopy (POM), Differential Scanning Calorimetry (DSC) and Spontaneous Polarization (PS) techniques. Observations infer a bi-variant FE LC smectic phase occurrence, viz., isotropic→B2(FE)→B 5(FE)→solid phases in cooling and solid→B 5→isotropic phases in heating scans. Occurrence of B2 phase is monotropic (in cooling), while B5 phase is enantiotropic. IB2 and B2B5 phase transitions are found to be of first order nature. The FE phases possess a moderate PS value of ∼40 nC cm-2. Transition temperatures from dielectric studies agree with those from TM and DSC. Two modes of relaxations are observed, viz., a slow scissor mode at ∼1 kHz and a fast mode at ∼1 MHz. Anisotropic Dipolar Model is proposed to explain the reorientation mechanism. Arrhenius shifts of Relaxation Frequency (fR) show differing activation energies for two modes, i.e., 0.11 and 0.98 eV; 0.25 and 1.18 eV in B 2 and B5 phases, respectively. Temperature variation of dielectric increment Δε and α-parameter LC phases reveals the relative fixture of dipole moment in polar smectic layers. An analytical study for the thermal stability, PS and fR in the FE phases is presented with respect to the constitution and configuration of moieties in BLCs.

AB - The occurrence of ferroelelectric phases and influence of chemical moieties in the area of supra-molecular achiral Bent core Liquid Crystals (BLCs) are reviewed. Synthesis of an intermediate/higher homolog of PBnOB series (for n=11), PBUOB, viz. 1,3-Phenyline-Bis(4-UndecylOxy Benzoate), is presented. Smectic LC phases exhibited by PBUOB are characterized by Polarized Optical Microscopy (POM), Differential Scanning Calorimetry (DSC) and Spontaneous Polarization (PS) techniques. Observations infer a bi-variant FE LC smectic phase occurrence, viz., isotropic→B2(FE)→B 5(FE)→solid phases in cooling and solid→B 5→isotropic phases in heating scans. Occurrence of B2 phase is monotropic (in cooling), while B5 phase is enantiotropic. IB2 and B2B5 phase transitions are found to be of first order nature. The FE phases possess a moderate PS value of ∼40 nC cm-2. Transition temperatures from dielectric studies agree with those from TM and DSC. Two modes of relaxations are observed, viz., a slow scissor mode at ∼1 kHz and a fast mode at ∼1 MHz. Anisotropic Dipolar Model is proposed to explain the reorientation mechanism. Arrhenius shifts of Relaxation Frequency (fR) show differing activation energies for two modes, i.e., 0.11 and 0.98 eV; 0.25 and 1.18 eV in B 2 and B5 phases, respectively. Temperature variation of dielectric increment Δε and α-parameter LC phases reveals the relative fixture of dipole moment in polar smectic layers. An analytical study for the thermal stability, PS and fR in the FE phases is presented with respect to the constitution and configuration of moieties in BLCs.

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