Improvement of the crystal rotation method to measure the flexoelectric difference (e sub(1)-e sub(3)) in achiral materials using AC electric fields

We show that the crystal rotation method for measuring the difference between splay and bend flexoelectric coefficients (e sub(1)-e sub(3)) [Outram and Elston, Liq. Cryst. 39, 149 (2012)] can be improved by using AC instead of DC fields. The field frequency is small (~0.05 Hz), yet sufficient to get...

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Bibliographic Details
Published inLiquid crystals Vol. 43; no. 10; pp. 1462 - 1471
Main Authors Etxebarria, J, Rodriguez-Conde, S, Ortega, J, Sanz-Enguita, G, Folcia, CL
Format Journal Article
LanguageEnglish
Published 08.08.2016
Subjects
Alternating current
Bend tests
Crystals
Dielectrics
Fittings
Liquid crystals
Migration
Temperature dependence
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Summary:We show that the crystal rotation method for measuring the difference between splay and bend flexoelectric coefficients (e sub(1)-e sub(3)) [Outram and Elston, Liq. Cryst. 39, 149 (2012)] can be improved by using AC instead of DC fields. The field frequency is small (~0.05 Hz), yet sufficient to get rid of the difficulties connected with the migration of charge carriers. The method is sensitive enough so as to use fields with amplitudes as small as 1 V/mm. This has the advantage of avoiding the consideration of the interaction due to the dielectric anisotropy, and greatly simplifies the analysis of data. The results are extracted from a simple fitting scheme, which involves two parameters. In particular (e sub(1)-e sub(3)) is obtained from a scale factor in a one-parameter fit. Measurements of the temperature dependence of (e sub(1)-e sub(3)) are presented for two classical nematic materials.
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ISSN:0267-8292
1366-5855
DOI:10.1080/02678292.2016.1181215