Study of different modes of dielectric relaxation in a newly synthesized material exhibiting ferro-, ferri- and antiferro-electric phases

Pandey, M. B.; Dhar, Ravindra; Agrawal, Veena; Dąbrowski, R.; Tykarska, Marzena

doi:10.1080/02678290410001709275

Cited by 53 publications

(60 citation statements)

References 28 publications

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“…In the antiferroelectric state, two characteristic modes are usually detected [4][5][6]12], i.e., the low-frequency antiferroelectric mode P L in the kHz region and P H mode at the higher frequencies. The possible interpretations of these two modes have been presented in details by Pandey et al [9]. According to the widely accepted interpretation, both these modes are related to collective excitation of molecules called in-phase azimuthal angle fluctuation P L and anti-phase azimuthal angle fluctuation P H as it was proposed by Buivydas et al [4].…”

Section: Resultsmentioning

confidence: 95%

“…Among a few other experimental methods, broadband dielectric spectroscopy has often been used to study the molecular relaxation in ferroelectric liquid crystalline materials [1,[4][5][6][7][8][9]. The technique enables us to obtain valuable information concerning phase sequences and molecular relaxations in ferroelectric and antiferroelectric liquid crystals.…”

Section: Introductionmentioning

confidence: 99%

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Dielectric properties of LC mixture with induced antiferroelectric phase

Wojciechowski¹,

Bąk

Tykarska

2008

Opto-Electronics Review

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Mixture of two liquid crystalline components exhibits the antiferroelectric phase in a broad temperature range at room temperatures, though the two components separately do not show an antiferroelectric phase in a temperature range applied. The dielectric spectroscopy technique combined with measurements of the selective light reflection was used for identification and characterization of the phases and subphases existing in the mixture. In the SmC*A phase, the low frequency mode characteristic of antiferroelectric phase has been detected. In the broad temperature range between SmC*A and SmA* phases, no relaxation mode has been detected. The soft mode registered near the phase transition to SmA* phase follows the Curie-Weiss law.

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Section: Resultsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Dielectric properties of LC mixture with induced antiferroelectric phase

Wojciechowski¹,

Bąk

Tykarska

2008

Opto-Electronics Review

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“…Dielectric data acquired in the frequency range of 1 Hz to 10 MHz suggest that low frequency (1 Hz to 10 kHz) data are highly affected by ionic impurities whereas high fre− quency data (above 1 MHz) are affected due to ITO resis− tance [26,27]. Effect of ionic impurities is more prominent in the homeotropic−aligned samples than in planar as a usual case.…”

Section: Resultsmentioning

confidence: 88%

“…The present work deals with the extensive thermodynamic and dielectric studies on the above men− tioned compounds in order to generalize the electrical behaviour of TGB phases. [26,27].…”

Section: Introductionmentioning

confidence: 99%

Characteristics of electrical properties of wide temperature range TGB phases in liquid crystal dimers

Dhar¹,

Pandey²,

Pandey³

et al. 2009

Opto-Electronics Review

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Abstract4-n-decyloxy-4′-(cholesteryloxycarbonyl-1-butyloxy) chalcone and its two successive homologous are optically active dimeric compound derived from cholesterol. They possess wide temperature ranges of two twist grain boundary (TGB) phases namely TGBA and TGBC*. Comprehensive dielectric studies have been carried out for these compounds in the frequency range of 1 Hz to 10 MHz for different conditions of molecular anchoring. Various electrical parameter viz. dielectric permittivity, dielectric anisotropy, dc conductivity, and activation energy have been determined for these two TGB phases. Weak relaxation processes have been detected under planar anchoring of molecules in the TGBA and TGBC* phases presumably due to amplitude (soft mode) and phase (Goldstone mode) fluctuations.

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“…, this mode is attributed to the soft mode arising due to tilt fluctuation of the director of the molecules in the smectic layers [10,15,16]. In some other AFLC compounds also, the soft mode of the SmA* phase is observed in the frequency range 10 kHz-1 MHz [8,16].…”

Section: Resultsmentioning

confidence: 90%