Observation and investigation of the ferrielectric subphase with highqTparameter

Abstract

Dielectric relaxation processes in an antiferroelectric liquid crystal ͑AFLC͒ have been investigated over a wide range of frequencies from 1 Hz to 1 GHz. The AFLC under investigation possesses a variety of different ferrielectric, ferroelectric, and antiferroelectric phases. Dielectric and polarization measurements under direct bias voltage have been made with a view to clarifying the origin of the high-temperature ferrielectric phase, which appears between the AF and smectic-C* phases. This phase is assigned to an unstable ferrielectric phase with q T parameter greater than 1/2 ͑according to the Ising model͒ or a doubly modulated incommensurate phase ͑according to the expanded Landau model͒. The results are also supported by conoscopy.

Transitional subphases near the electric-field-induced phase transition to the ferroelectric phase in Se-containing chiral smectic liquid crystals observed by resonant x-ray scattering

“…Nevertheless, the {R 6 L}(q E = 5/7) and {R 3 LRL 2 }(q E = 1/7) structures with a small value of δ were confirmed to provide a nearly equal intensity reflection pattern. However, {R 6 L} is likely to be realized, considering the q E values of both models. In summary, the C 6p and C 7p subphases have the {R 5 L} and {R 6 L} configuration, respectively, with relatively small value of δ, and, at these temperatures, the C 3p {R 2 L} phase directly transforms to the C 6p {R 5 L} subphase and then to the C 7p {R 6 L} subphase.…”

“…antiferroelectric AF (SmC * FI2 , SmC * d4 , or SmC * A (q T = 1/2)), ferrielectric SmC * γ (SmC * FI1 , SmC * d3 , or and other techniques [3,6,[27][28][29][30][31][32]. Recent RXS studies under an electric field directly revealed the electric field-induced phase transitions from the low field AF phase to the high field SmC * γ phases [33][34][35].…”

The effect of confinement on the stability of field induced states and on supercooling in antiferro-ferroelectric phase transitions in chiral smectic liquid crystals

“…Confinement effects using dielectric spectroscopy on antiferroelectric and ferroelectric liquid crystals in micro-and nano-confinement have been studied qualitatively and reported in the literature. [22][23][24] …”

The investigation of the relaxation processes in antiferroelectric liquid crystals by electro-optic spectroscopy

“…[3][4][5][6] The dielectric spectra in the frequency range from 10 Hz to 1 GHz show the existence of two collective relaxation processes and two molecular relaxation processes in the SmC A phase and these are denoted as Processes 0,1,2,3 with increasing of the relaxation frequency. 6 The lower frequency processes ͑Process 0 and Process 1͒ are found to exist 6 only in the two antiferroelectric phases SmC A and AF phases. The frequency of Process 0 is ϳ2.5 kHz, whereas that of Process 1 lies between 10 and 70 kHz depending on the temperature.…”

“…A determination of the origin of the collective modes will allow for a further improvement in these materials to occur with regard to their switching speeds and hence increase their usefulness for displays and electro-optic devices. A study of the relaxation processes has been made using dielectric spectroscopy, [3][4][5][6] electro-optics, 4 and photon correlation spectroscopy. 7 Nevertheless, the problem of finding the mechanisms governing the various relaxation processes in the antiferroelectric phase has not yet been solved and the aim of this letter is to unambiguously establish these mechanisms using electrooptic spectroscopy of a AFLC.…”