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Title: Flexoelectricity in an oxadiazole bent-core nematic liquid crystal

We have determined experimentally the magnitude of the difference in the splay and bend flexoelectric coefficients, |e{sub 1} − e{sub 3}|, of an oxadiazole bent-core liquid crystal by measuring the critical voltage for the formation of flexodomains together with their wave number. The coefficient |e{sub 1} − e{sub 3}| is found to be a factor of 2–3 times higher than in most conventional calamitic nematic liquid crystals, varying from 8 pCm{sup −1} to 20 pCm{sup −1} across the ∼60 K—wide nematic regime. We have also calculated the individual flexoelectric coefficients e{sub 1} and e{sub 3}, with the dipolar and quadrupolar contributions of the bent-core liquid crystal by combining density functional theory calculations with a molecular field approach and atomistic modelling. Interestingly, the magnitude of the bend flexoelectric coefficient is found to be rather small, in contrast to common expectations for bent-core molecules. The calculations are in excellent agreement with the experimental values, offering an insight into how molecular parameters contribute to the flexoelectric coefficients and illustrating a huge potential for the prediction of flexoelectric behaviour in bent-core liquid crystals.
Authors:
; ;  [1] ; ;  [2] ;  [3] ;  [4] ;  [3]
  1. School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom)
  2. Department of Chemical Sciences, University of Padua, Padua I-35131 (Italy)
  3. Department of Chemistry, University of York, York YO10 5DD (United Kingdom)
  4. (United Kingdom)
Publication Date:
OSTI Identifier:
22402435
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 22; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; DENSITY FUNCTIONAL METHOD; DIELECTRIC MATERIALS; DIELECTRIC PROPERTIES; LIQUID CRYSTALS; OXADIAZOLES; POLARIZATION; SIMULATION