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The beauty of twist-bend nematic phase: Fast switching domains, first order fréedericksz transition and a hierarchy of structures

Panov, Vitaly P.; Song, Jang Kun; Mehl, Georg H.; Vij, Jagdish K.

Authors

Vitaly P. Panov

Jang Kun Song

Jagdish K. Vij



Contributors

Abstract

The twist-bend nematic phase (NTB) exhibits a complicated hierarchy of structures responsible for several intriguing properties presented here. These are: the observation of a fast electrooptic response, the exhibition of a large electroclinic effect, and the observation of an unusual pattern of the temperature dependence of birefringence of bent-shaped bimesogens in parallel-rubbed planar-aligned cells. These unusual effects inspired the use of highly sophisticated techniques that led to the discovery of the twist-bend nematic phase. Results of the optical retardation of a parallel-rubbed planar-aligned cell show that the ‘heliconical angle’ (the angle the local director makes with the optical axis) starts increasing in the high temperature N phase, it exhibits a jump at the N–NTB transition temperature and continues to increase in magnitude with a further reduction in temperature. The liquid crystalline parallel-rubbed planar-aligned and twist-aligned cells in this phase exhibit fascinating phenomena such as a demonstration of the beautiful stripes and dependence of their periodicity on temperature. The Fréedericksz transition in the NTB phase is found to be of the first order both in rubbed planar and homeotropic-aligned cells, in contrast to the second order transition exhibited by a conventional nematic phase. This transition shows a significant hysteresis as well as an abrupt change in the orientation of the director as a function of the applied electric field. Hierarchical structures are revealed using the technique of polymer templating the structure of the liquid crystalline phase of interest, and imaging of the resulting structure by scanning electron microscopy

Citation

Panov, V. P., Song, J. K., Mehl, G. H., & Vij, J. K. (2021). The beauty of twist-bend nematic phase: Fast switching domains, first order fréedericksz transition and a hierarchy of structures. Crystals, 11(6), 621. https://doi.org/10.3390/cryst11060621

Journal Article Type Article
Acceptance Date May 25, 2021
Online Publication Date May 31, 2021
Publication Date May 31, 2021
Deposit Date Jun 2, 2021
Publicly Available Date Jun 3, 2021
Journal Crystals
Electronic ISSN 2073-4352
Publisher MDPI
Peer Reviewed Peer Reviewed
Volume 11
Issue 6
Pages 621
DOI https://doi.org/10.3390/cryst11060621
Keywords Inorganic Chemistry; General Materials Science; General Chemical Engineering; Condensed Matter Physics
Public URL https://hull-repository.worktribe.com/output/3778135

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Copyright Statement
Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).





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