ABSTRACT
We show that the crystal rotation method for measuring the difference between splay and bend flexoelectric coefficients (e1–e3) [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 (e1–e3) is obtained from a scale factor in a one-parameter fit. Measurements of the temperature dependence of (e1–e3) are presented for two classical nematic materials.
Graphical Abstract
![](/cms/asset/2ef32aba-fcb8-4508-a540-52b9eb1f724f/tlct_a_1181215_uf0001_oc.jpg)
Acknowledgements
This work is supported by the Basque Government (Project IT 1130-16). S. R-C and G. S-E thank the UPV/EHU for a grant.
Disclosure statement
No potential conflict of interest was reported by the authors.