Ferrielectric six-layer  () and several electric-field-induced subphases in AS657 studied by complementary methods, electric-field-induced birefringence and microbeam resonant X-ray scattering

Perera, A. D. L. Chandani; Fukuda, Atsuo; Vij, J. K.; Takanishi, Yoichi

doi:10.1080/02678292.2017.1385104

Cited by 6 publications

(4 citation statements)

References 56 publications

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“…Here we designate the subphase as the ratio q T = [F ]/([F ] + [A]), where [F ] and [A] are the numbers of ferroelectric and antiferroelectric orderings in the unit cell. Recently, the definite existence of subphases 1/4 and 2/5 with eight-and ten-layer unit cells, respectively, was vindicated by studying electric-field-induced birefringence (EFIB) and microbeam resonant x-ray scattering (μRXS) [6,7]. This indicates the importance of the effective LRILI based on the seminal "discrete flexoelectric effect" [8], as any direct LRILI to produce the ten-layer ordered superlattice structure is hard to consider in smectics with no long-range positional order.…”

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confidence: 99%

“…2 of Ref. [7]. Experimental studies were made by the complementary methods: EFIB in homeotropically aligned cells to obtain the field-temperature (E -T ) phase diagram with birefringence contours and μRXS in homogeneously aligned (smectic layers almost perpendicular to substrate plates) planar cells to determine the superlattice structure of the field-induced subphases.…”

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“…Experimental studies were made by the complementary methods: EFIB in homeotropically aligned cells to obtain the field-temperature (E -T ) phase diagram with birefringence contours and μRXS in homogeneously aligned (smectic layers almost perpendicular to substrate plates) planar cells to determine the superlattice structure of the field-induced subphases. We refer to the previous papers [6,7] for the experimental details; in particular, we followed the conventions that the electric field was applied along the y axis and that EFIB was defined as n = n x − n y as in the previous papers.…”

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Unexpected electric-field-induced antiferroelectric liquid crystal phase in the SmCα* temperature range and the discrete flexoelectric effect

et al. 2019

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The unique nanometer-sized helical structure in SmC * α may sometimes evolve continuously to the micrometersized one in SmC * ; conceivably ferroelectric SmC * α is to be unwound by an applied electric field. By drawing electric-field-induced birefringence contours in the field-temperature phase diagram and by studying the superlattice structure of the field-induced subphase with resonant x-ray scattering, we established that an applied field unexpectedly stabilizes the well-known antiferroelectric four-layer biaxial subphase as well as the other prototypal ferrielectric three-layer one in the SmC * α temperature range; the effective long-range interlayer interaction due to the discrete flexoelectric effect actually plays an important role in stabilizing not only the biaxial subphases but also the optically uniaxial SmC * α subphase, contrary to the notion that the competition between the direct interactions of the nearest-neighbor layers and those of the next-nearest-neighbor layers should be required for the nanometer-sized helical structure.

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Unexpected electric-field-induced antiferroelectric liquid crystal phase in the SmCα* temperature range and the discrete flexoelectric effect

et al. 2019

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“…4(g)]. The three experimentally obtained C 6p structures were the {R 3 L 3 } (δ = 27°) [14,16] and the {R 4 L 2 } [17,37] configurations without an electric field, and the {R 5 L} configuration under an electric field [30]. Other possible C 6p configurations have also been discussed [15,30].…”

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Resonant x-ray scattering observation of transitional subphases during the electric-field-induced phase transition in a mixture of Se-containing chiral smectic liquid crystals

et al. 2018

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Using resonant x-ray scattering techniques, transitional subphases during the electric-field-induced phase transition of a mixture of Se-containing chiral liquid crystals, 80% AS657 and 20% AS620, in a planar-aligned cell geometry were investigated, where the prototypical phase sequence SmC_{A}^{*}-SmC_{γ}^{*}-AF-SmC^{*} was observed; the transitional subphases were formed during the transition from the three-layer periodicity phase to the ferroelectric phase. In the lower-temperature range where the three-layer SmCγ^{*} phase appeared under the low electric field, nine- and six-layer subphases and a "streak" pattern appeared in sequence after the transition from the SmCγ^{*} phase with increasing applied electric field; the ferroelectric phase was realized. In the higher-temperature range where the four-layer AF phase appeared under a low electric field, the AF phase changed to a three-layer phase at the medium electric field. The twelve-, nine-, and six-layer subphases subsequently appeared in sequence, and finally the ferroelectric phase was generated with increasing electric field. The molecular arrangements of the field-induced subphases, especially the newly found nine-layer periodicity phase, was analyzed. The successive field-induced phase transition of the present results was compared with that of our previous results for pure Se-containing and Br-containing liquid crystals, and the relation to the three-layer ferrielectric phase was discussed.

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Dielectric study of a subphase stabilized in an exceptionally wide temperature range by a delicate balance of interlayer interactions and thermal fluctuations

et al. 2020

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Ferrielectric six-layer () and several electric-field-induced subphases in AS657 studied by complementary methods, electric-field-induced birefringence and microbeam resonant X-ray scattering

Cited by 6 publications

References 56 publications

Unexpected electric-field-induced antiferroelectric liquid crystal phase in the SmCα* temperature range and the discrete flexoelectric effect

Unexpected electric-field-induced antiferroelectric liquid crystal phase in the SmCα* temperature range and the discrete flexoelectric effect

Resonant x-ray scattering observation of transitional subphases during the electric-field-induced phase transition in a mixture of Se-containing chiral smectic liquid crystals

Dielectric study of a subphase stabilized in an exceptionally wide temperature range by a delicate balance of interlayer interactions and thermal fluctuations

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