Observation of dielectric relaxation modes in chiral smectic C liquid crystal mixture

Singh, Rajnish Kumar; Agarwal, V.K.; Raina, K. K.; Bahadur, Birendra

doi:10.1016/j.cap.2004.08.001

Cited by 11 publications

(4 citation statements)

References 20 publications

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“…It was seen that the MWS process was dominant in the low-frequency range; while at higher frequencies, the soft mode was visible (in the insets). As is known, the relaxation frequency for this process is temperature-dependent, especially in the vicinity of the SmA*–SmC* phase transition, where the V-shaped behavior is usually observed [ 48 , 49 , 50 ]. For Composites 3–5, the full V-shape behavior of the relaxation frequency was not visible (see Figure 8 b), as the SM disappeared completely after phase transition to the SmC* phase.…”

Section: Resultsmentioning

confidence: 99%

Modifications of EHPDB Physical Properties through Doping with Fe2O3 Nanoparticles (Part II)

Lalik

Stefańczyk

Górska

et al. 2021

IJMS

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The aim of our study was to analyze the influence of various concentrations of γ-Fe2O3 nanoparticles on the physical properties of the liquid crystalline ferroelectric SmC* phase, as well as to check the effect of introducing nanoparticles in the LC matrix on their properties in the prepared five nanocomposites. UV-vis spectroscopy showed that the admixture reduced the absorption of nanocomposites in the UV range, additional absorption bands appeared, and all nanocomposites were transparent in the range of 500–850 nm. The molecular dynamics in particular phases of the nanocomposites were investigated by the dielectric spectroscopy method, and it was found that nanoparticles caused a significant increase in the dielectric constant at low frequencies, a strong modification of the dielectric processes in the SmC* phase, and the emergence of new relaxation processes for the highest dopant concentrations. SQUID magnetometry allowed us to determine the magnetic nature of the nanoparticles used, and to show that the blocked state of nanoparticles was preserved in nanocomposites (hysteresis loops were also registered in the ferroelectric SmC* phase). The dependence of the coercive field on the admixture concentration and the widening of the hysteresis loop in nanocomposites in relation to pure nanoparticles were also found. In turn, the FT-MIR spectroscopy method was used to check the influence of the impurity concentration on the formation/disappearance or modification of the absorption bands, and the modification of both the FWHM and the maximum positions for the four selected vibrations in the MIR range, as well as the discontinuous behavior of these parameters at the phase transitions, were found.

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Section: Resultsmentioning

confidence: 99%

Modifications of EHPDB Physical Properties through Doping with Fe2O3 Nanoparticles (Part II)

Lalik

Stefańczyk

Górska

et al. 2021

IJMS

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“…SmC* phase transition has also been observed [7]. Some research groups [8][9][10][11][12] reported the existence of another mode in the SmC* phase that could arise due to the dominant surface interactions between cell substrates and the liquid-crystalline material. Very recently, efforts have also been made to study the effect of dichroic dyes on the dielectric relaxation mechanism of FLC mixtures [13][14][15].…”

Section: Introductionmentioning

confidence: 93%

Dielectric spectroscopy of a high-polarization ferroelectric liquid crystal

et al. 2006

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Dielectric spectroscopy investigations in the frequency range 50 Hz to 1 MHz have been carried out on a new ferroelectric liquid-crystalline material (S-(-)-4-(2-n-hexylpropionyloxy)biphenyl-4 0 -(3-methyl-4-decyloxy)benzoate) possessing a relatively large spontaneous polarization (P s $ 240 nC cm À2 ) and containing a lateral methyl group on the aromatic ring of the alkoxybenzoate unit. The effect of temperature on the dielectric relaxation modes has been investigated in the SmC* and N* phases. From dielectric dispersion data, relaxation frequency and dielectric strength of all detected relaxation modes have been evaluated and discussed. A new surface-like mode of relaxation frequency $11 kHz and dielectric strength 3.8, is seen to appear in the SmC* phase.

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“…9(a & b) shows complex relative dielectric constant plots of imaginary part vs real part at various temperatures. These plots obey the Cole-Cole type dispersion with a distribution of relaxation time [31,38]. Semicircular shapes of the Cole-Cole plots highlight the mono-dispersive nature of the dielectric study of this PDLC composite system.…”

Section: Dielectric Responsementioning

confidence: 99%

Investigation of liquid crystal dispersion and dielectric relaxation behavior in polymer dispersed liquid crystal composite films

Parab¹,

Malik²,

Bhatia³

et al. 2014

Journal of Molecular Liquids

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Observation of dielectric relaxation modes in chiral smectic C liquid crystal mixture

Cited by 11 publications

References 20 publications

Modifications of EHPDB Physical Properties through Doping with Fe2O3 Nanoparticles (Part II)

Modifications of EHPDB Physical Properties through Doping with Fe2O3 Nanoparticles (Part II)

Dielectric spectroscopy of a high-polarization ferroelectric liquid crystal

Investigation of liquid crystal dispersion and dielectric relaxation behavior in polymer dispersed liquid crystal composite films

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