Addis, J, Kaur, S, Binks, DJ et al. (6 more authors) (2016) Second-harmonic generation and the influence of flexoelectricity in the nematic phases of bent-core oxadiazoles. Liquid Crystals, 43 (10). pp. 1315-1332. ISSN 0267-8292
Abstract
Second-harmonic generation (SHG) in the nematic phase of bent-core oxadiazole-based liquid crystals (LCs) was studied and compared to that for the rod-like compound 4-cyano-4ʹ-n-octylbiphenyl (8CB). Weak, isotropically scattered second-harmonic (SH) light was observed for all materials, consistent with SHG by nematic director fluctuations. The SH intensity produced by the bent-core materials was found to be up to ~ 3.4 times that of 8CB. We discuss this result in terms of the dependence of SH intensity on temperature, elastic constants and flexoelectric coefficients. We have calculated the latter by using a molecular field approach with atomistic modelling, thus demonstrating how molecular parameters contribute to the flexoelectric coefficients and illustrating the potential of this method for predicting the flexoelectric behaviour of bent-core LCs. We show that the increased SH signal in the bent-core compounds is partly due to their nematic phases being at a much higher temperature, and also potentially due to them having greater flexoelectric coefficients, up to ~1.5 times those of 8CB. These estimates are consistent with reports of increased flexoelectric coefficients in bent-core compounds in comparison to rod-like compounds.
Metadata
Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2016 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricteduse, distribution, and reproduction in any medium, provided the original work is properly cited. |
Keywords: | Nematic liquid crystals, bent-core liquid crystals, non-linear optics, second-harmonic generation, flexoelectric coefficients |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemical & Process Engineering (Leeds) The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) > Soft Matter Physics (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 16 May 2016 09:26 |
Last Modified: | 11 Apr 2018 13:21 |
Published Version: | http://dx.doi.org/10.1080/02678292.2016.1172355 |
Status: | Published |
Publisher: | Taylor & Francis |
Identification Number: | https://doi.org/10.1080/02678292.2016.1172355 |
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