Fluctuations in the ferrielectric smectic-Cγ* phase as observed by laser beam diffraction and photon correlation spectroscopy

Antiferroelectric and ferroelectric orderings in frustrated chiral tilted smectics and a continuous change from anticlinic SmC A * to synclinic SmC *

“…They obtained α = 2.5 × 10 3 erg • cm −3 • K −1 in the 50 wt.% mixture. This corresponds to 5 × 10 4 erg • cm −3 at T − T c = 20 K and which is three orders of magnitude smaller than the thermal energy k B T /(volume per molecule) at 300 K. Note that the dynamical flip-flopping of a smectic layer has been known to show a very slow relaxation, 132 Hz, in the autocorrelation of the laser beam diffraction intensity observed in SmC * A (1/3) of MHPOBC [21]. It is suggested that the photon correlation spectroscopy experiment on the 53.74 wt.% mixture must be useful in elucidating the details of the dynamical flip-flopping processes.…”

Molecular Orientational Structures with Macroscopic Helix in Antiferroelectric Liquid Crystal Subphases

“…The less obvious diffraction and the lack of reproducibility are characteristic features of SmC * γ . 34) The temperature dependences of the helical pitch and ORP are shown in Fig. 2.…”

“…The phenomenological Landau model has been developed to explain the subphases phenyl 4 -octyloxybiphenyl)-4-carboxylate) and laser light diffraction in the SmC * γ and AF phases of R-MHPBC (4-(1-methylheptyloxycarbonyl)phenyl 4 -octylbiphenyl)-4carboxylate) 34,35) have been reported. In this paper, the observation of the helical structure and ORP in subphases in a partially racemized MHPBC will be reported, providing experimental facts against the XY model.…”

Superlattice structures observed in the extraordinary phase sequence and analyzed by the phenomenological Landau model and the partially molecular model

“…Regarding the noisy region Wang et al identified [22], we would like to point out that 3 5 is ferrielectric and that any ferrielectric phase may be noisier. Even in the well established ferrielectric subphase 1 3 , the disordered structure and lowfrequency fluctuations were observed by laser beam diffraction and photon correlation spectroscopy [49]. This intrinsic instability has been ascribed to a tendency of neutralizing the spontaneous polarization spatially and thus reducing the Coulomb interaction energy; solitonlike mismatches are easily produced here and there by interchanging the antiferroelectric and ferroelectric orderings, thus causing thermal fluctuations in the helicoidal structures [49].…”

“…Even in the well established ferrielectric subphase 1 3 , the disordered structure and lowfrequency fluctuations were observed by laser beam diffraction and photon correlation spectroscopy [49]. This intrinsic instability has been ascribed to a tendency of neutralizing the spontaneous polarization spatially and thus reducing the Coulomb interaction energy; solitonlike mismatches are easily produced here and there by interchanging the antiferroelectric and ferroelectric orderings, thus causing thermal fluctuations in the helicoidal structures [49]. Levelut and Pansu also wrote that the RXRS experiments have revealed the existence of defects in 1 3 since the resonant satellite peaks show a complex structure with several side bands [15].…”