Browsing by Author "VIJ, JAGDISH"
Now showing items 21-40 of 58
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Effective long-range interlayer interactions and electric-field-induced subphases in ferrielectric liquid crystals
VIJ, JAGDISH (2016)Microbeam resonant x-ray scattering experiments recently revealed the sequential emergence of electric- field-induced subphases (stable states) with exceptionally large unit cells consisting of 12 and 15 smectic layers. ... -
Electric field induced biaxiality and the electro-optic effect in a bent-core nematic liquid crystal
VIJ, JAGDISH; PANARIN, YURI; MANNA, UTTAM (2010)We report the observation of a biaxial nematic phase in a bent-core molecular system using polarizing microscopy, electro-optics, and dielectric spectroscopy, where we find that the biaxiality exists on a microscopic scale. ... -
Electric-field-dependent dielectric response in the de Vries-type smectic- A* phase possessing local orientational order with nanoscale correlation length
VIJ, JAGDISH; MANNA, UTTAM; SONG, JANG-KUN (2008)The dielectric strength is shown to increase and the relaxation frequency to decrease for a large temperature range up to a certain value of the electric field in the smectic-A* phase. This behavior contrasts to that ... -
Electro-optic and dielectric study of the de Vries-type smectic- A phase exhibiting transitions to smectic- CA and smectic- C phases
PANARIN, YURI; VIJ, JAGDISH; FUKUDA, ATSUO; MANNA, UTTAM; SONG, JANG-KUN (2008)Mixtures of different compositions of an antiferroelectric liquid crystal compound that exhibits direct smectic-A Sm-A -smectic-CA Sm-CA transition with a ferroelectric liquid crystal compound that exhibits Sm-A -smectic-C ... -
Evidence of deVries structure in a smectic-A liquid crystal observed by polarized Raman scattering
VIJ, JAGDISH; FUKUDA, ATSUO; PANARIN, YURI (2005)The second- and fourth-order apparent orientational order parameters of the core part of the molecule kP2lapp and kP4lapp, have been measured by polarized vibrational Raman spectroscopy for a homogeneously aligned ferroelectric ... -
Experimental demonstration, using polarized Raman and infrared spectroscopy that both conventional and de Vries smectic_A phase may exist in smectic liquid crystals with a first-order A-C* transition
VIJ, JAGDISH; FUKUDA, ATSUO (2006)Two models exist for the orientational distribution of the long molecular axes in smectic-A liquid crystals: the conventional unimodal distribution and the ?cone-shaped? de Vries distribution. The de Vries hypothesis provides ... -
Experimental study of high-temperature smectic- C FI2 phase in chiral smectic liquid crystals that exhibit phase-sequence reversal
VIJ, JAGDISH; SONG, JANG-KUN; PANARIN, YURI (2008)We report the results of an experimental study of a recently observed phase sequence reversal of smectic-C<sub>FI2</sub><sup>*</sup> [SmC*(qT=1/2); a four layer antiferroelectric] phase appearing in the temperature range ... -
Exponential kinetics of spontaneous change in the localized motions of D-sorbitol glass
VIJ, JAGDISH (2006)The dielectric relaxation spectra of D -sorbitol glass have been studied in real time during annealing at 221.1 K, which is 47 K below its Tg of 268 K. As the glass structurally relaxes during annealing, features of the ... -
Field-induced periodic chiral pattern in the Nx phase of achiral bimesogens
VIJ, JAGDISH; PANOV, VITALI (2012)Some hydrocarbon-linked mesogenic dimers are known to exhibit an additional nematic phase (Nx) in the temperature range below the conventional nematic (Nu) phase. One of the features of this phase is the presence of optical ... -
Gold nanorods embedded discotic nanoribbons
VIJ, JAGDISH (2013)It is shown that gold nanorods (GNRs) can be easily inserted into the supramolecular order of discotic liquid crystals (DLCs) along the director without disturbing their mesomorphism. GNRs embedded discotic nanoribbons, ... -
Gradual phase transition between the smectic- C* and smectic- CA* phases and the thresholdless antiferroelectricity
VIJ, JAGDISH; SONG, JANG-KUN; FUKUDA, ATSUO (2008)We have constructed the phase diagrams for a binary-mixture system of antiferroelectric and ferroelectric liquid-crystalline materials in both thick and thin cells. In the phase diagrams the boundary between the smectic-C* ... -
Hierarchical elasticity of bimesogenic liquid crystals with twist-bend nematic phase
VIJ, JAGDISH; VENKATESAN, MUNUSWAMY (2015)in 2001, Dozov predicted that twist-bend nematic phase can be spontaneously formed when K 33 < 0 and K 11/K 22 > 2, and this phase has recently been discovered in bimesogens. To verify Dozov's hypothesis, we have measured ... -
Interlayer interactions and the dependence of biaxiality of the chiral smectic- C* phase on electric field in the helical unwinding process
VIJ, JAGDISH; SONG, JANG-KUN (2007)We investigate the unwinding process of pure and racemized mixtures of 1-methylheptyloxycarbonyl phenyl-4 -carboctyloxy-biphenyl-4-carboxylate MHPOOCBC in homeotropic cells by studying i the optical texture under ... -
Investigations of nano-scale helical pitch in SmCá* and SmC* phases of a chiral smectic liquid crystal using differential optical reflectivity measurements
VIJ, JAGDISH; PANOV, VITALI (2006)Differential optical reflectivity (DOR) was used to study the temperature dependence of the short helical pitch in freestanding films of a liquid crystal compound. The experimentally measured DOR signal was fitted using ... -
Investigations of nanoscale helical pitch in smectic-C and smectic-C* phases of a chiral smectic liquid crystal using differential optical reflectivity measurements
VIJ, JAGDISH (2006)Differential optical reflectivity DOR was used to study the temperature dependence of the short helical pitch in freestanding films of a liquid crystal compound. The experimentally measured DOR signal was fitted using ... -
Macroscopic biaxiality and electric-field-induced rotation of the minor director in the nematic phase of a bent-core liquid crystal
NAGARAJ, MAMATHA; VIJ, JAGDISH (2010)Biaxiality in the nematic phase has been investigated for the bent-core liquid-crystal para-heptylbenzoate diester, using polarised IR spectroscopy. Anisotropic fluctuations of the nematic director are discussed in terms ... -
Mechanism of field-induced unwinding of SmC* helix and biasfield dependencies of dielectric permittivity and effective polarization
VIJ, JAGDISH; SONG, JANG-KUN; MANNA, UTTAM (2008)We propose an unwinding model based on helical fractures confirmed by spectroscopic and microscopic observations. This model combined with the fixed helical pitch can explain the various physical phenomena observed in ... -
Microsecond linear optical response in the unusual nematic phase of achiral bimesogens
VIJ, JAGDISH; BALACHANDARAN, RESHMA; NAGARAJ, MAMATHA; PANOV, VITALI (2011)Some hydrocarbon linked mesogenic dimers are known to exhibit an additional nematic phase (N(x)) below a conventional uniaxial nematic (N(u)) phase. Although composed of non-chiral molecules, the N(x) phase is found to ... -
Molecular model of biaxial ordering in nematic liquid crystals composed of flat molecules with four mesogenic groups
VIJ, JAGDISH; KOCOT, ANTONI (2010)Relative stability of uniaxial and biaxial nematic phases is analyzed in a model nematic liquid crystal composed of flat molecules of C-2h symmetry with four mesogenic groups rigidly linked to the same center. The generalized ... -
Molecular orientation and the infrared dichroism of a chiral smectic liquid crystal in a homogeneouslyusly aligned cell at different temperatures and bias fields
VIJ, JAGDISH (2003)The molecular orientation and the dichroic behavior of the vibrational bands of a homogeneously aligned helical cell containing chiral smectic liquid crystal ~R!-~-!-1-methylheptyl 4- (48-dodecyloxybiphenyl-4-ylcarbony ...