DOI: 10.1051/jp2:1993117
J. Phys. II France 3 (1993) 147-164

Flexoelectricity and alignment phase transitions in nematic liquid crystals

R. Barberi^{1, 2}, G. Barbero^{1, 3}, Z. Gabbasova^{1, 4} and A. Zvezdin<sup>3, 5

1</sup>  Dipartimento di Fisica, Università della Calabria, 87036 Arcavata di Rende (CS), Italy
²  Facoltà a di Ingegneria, Università di Reggio Calabria, Via Cuzzocrea 48, 899128 Reggio Calabria, Italy
³  Dipartimento di Fisica, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
⁴  Theoretical Physics Department, Bashkir State University, Uliza Frunze 32, 450074 Ufa, Russia
⁵  Institute of General Physics, Russian Academy of Sciences, Uliza Valivola 38, 117942 Moscow, Russia

(Received 13 March 1992, revised 25 September 1992, accepted 28 September 1992)

Abstract
The influence of the flexoelectric effect on the phase diagram relevant to the order transition induced by an electric field on a nematic liquid crystal is considered. The analysis shows that this influence can be important. It is found that the order phase transition between the initially undistorted and distorted configurations always takes place. In contrast, the phase transition between the distorted and the saturated configurations is possible only if the dielectric anisotropy is large enough. The stability of the phases is analysed. The existence of a tricritical point is predicted. The dependence of the tricritical point on the flexoelectric coefficient is discussed too. The limits of our calculations and the performed simplifying hypotheses are critically analysed.

PACS
61.30

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