Flexoelectricity of twist-bend nematics

Postgraduate Thesis uoadl:2770553 337 Read counter

Unit:
Κατεύθυνση Φυσική των Υλικών (ΒΑΣΙΚΗ ΦΥΣΙΚΗ)
Library of the School of Science
Deposit date:
2018-06-15
Year:
2018
Author:
Kume Eni
Supervisors info:
Ιωάννης Λελίδης, Επίκουρος Καθηγητής, Τμήμα Φυσικής, Εθνικό και Καποδιστριακό Πανεπιστήμιο Αθηνών
Βλάσιος Λυκοδήμος, Επίκουρος Καθηγητής, Τμήμα Φυσικής, Εθνικό και Καποδιστριακό Πανεπιστήμιο Αθηνών
Αντώνιος Παπαθανασίου, Επίκουρος Καθηγητής, Τμήμα Φυσικής, Εθνικό και Καποδιστριακό Πανεπιστήμιο Αθηνών
Original Title:
Κυρτο-ηλεκτρικό φαινόμενο περιοδικών νηματικών κρυστάλλων
Languages:
Greek
Translated title:
Flexoelectricity of twist-bend nematics
Summary:
In this Master's degree thesis, we studied the flexoelectric effect in twist-bend nematic liquid crystals. Firstly, we studied the effect of the classic flexoelectric terms in nematic and cholesteric phases. Then, by taking into account the elements of symmetry of the TB phase, we demonstrated the existence of extra flexoelectric terms. Moreover, we investigated the variation of polar angle θ, the period p of the helix pitch and the tilt angle α under an external electric field. Next, the characteristic relaxation time have been invastigated. Also, we studied the classic flexoelectric model for the twist-bend nematics and we compared the results of both models. Finally, we compared the prediction of our model with experimental data and we found a resonable agreement. In particular, the origin of the flexoelectric polarization increase has been elucidated.
Main subject category:
Science
Keywords:
cholesteric phase, twist-bend nematic phase, electric field, dielectric coupling, flexoelectricity, flexoelectric coefficients, characteristic time
Index:
Yes
Number of index pages:
2
Contains images:
Yes
Number of references:
47
Number of pages:
84
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