Direct flexoeffect in nematics close to clearing point

O.A. Denisova1, O.A. Skaldin2
1Ufa state petroleum technological University, ul. Chernyshevskogo, 145, 450076, Ufa, Russia
2Федеральное государственное бюджетное учреждение науки Институт физики молекул и кристаллов Уфимского научного центра Российской академии наук, 450075, РБ, г. Уфа, Проспект Октября, д.151
Abstract
The peculiarities of direct flexoeffect in nematic liquid crystals (NLC) in the vicinity of the clearing point have been studied experimentally. N-butyl-aniline-methoxybenzylidene (MBBA) and dvuhkolchaty ether were the objects of the study. Flexoeffect, as a kind of piezoelectric effect, was observed as a result of the impact of transverse (shear) waves on the homeotropic NLC layer. Electrooptical NLC cell was of sandwich type, in which the excitation of the transverse shear wave was drived by the longitudinal oscillations of one glass substrate coated by conductive layer. The registration of a polarization voltage U1,2, induced in the NLC layer by a periodic deformation of the director field was carried out by two ways: the first - U2 was recorded between the movable plate and fixed substrate, the second - U1 was measured on the fixed substrate. The two possible mechanism of U1,2 voltage generation have been considered. The first one was associated with the polarization potential formation due to the flexoeffect, the second – because of orientational deformation of the surface polarization Ps layer. That is, both mechanisms to the detected signal in varying degrees contribute. Analyzing the temperature changes of the periodic shear induced polarization in the NLC layer in the neighborhood of a phase transition in the isotropic phase, the conclusion of significant contribution of the surface polarization was done. The recorded potential difference in the isotropic phase was related to the Maxwell effect.
Received: 11 May 2016   Revised: 28 July 2016   Accepted: 01 August 2016
Views: 57   Downloads: 14
References
1.
R.B. Meyer. Phys. Rew. Lett., 22, 917, (1969).
2.
S.A. Pikin. Structural transformations in liquid crystals. Science, M. CH. ed. Fiz.-Mat. lit. (1981). 336 (in Russian) [С.А. Пикин. Структурные превращения в жидких кристаллах. Наука, М. Гл. ред. физ.-мат. лит. (1981). 336 с]
3.
L.M. Blinov. Electro - and magnetooptics of liquid crystals. Science, M. CH. ed. Fiz.-Mat. lit. (1978). 384 p. (in Russian) [Л.М. Блинов. Электро- и магнитооптика жидких кристаллов. Наука, М. Гл. ред. физ.-мат. лит. (1978). 384 с]
4.
L.M. Blinov. Liquid crystals. LIBROKOM. M. (2013). 480 p. (in Russian) [Л.М. Блинов. Жидкие кристаллы. ЛИБРОКОМ. М. (2013). 480 с]
5.
A. Krekhov, W. Pesch, N. Eber et al. Phys. Rew. E 77, 021705 (2008).
6.
A. Krekhov, W. Pesch, A. Buka. Phys. Rew. E 83, 051706 (2011).
7.
T. Toth-Katona, N. Eber, A. Buka and A. Krekhov. Phys. Rew. E 78, 036206 (2008).
8.
M. May, W. Schopf, A.G. Rossberg et al. Phys. Rew. E 78, 046215 (2008).
9.
G. Barbero, A.P. Krekhov, A.N. Chuvyrov, O.A.Skaldin. J. Appl. Phys. 69 (9), 6343 (1991).
10.
O.A. Denisova, O.A. Scaldin Electrotechnical and information complexes and systems. 4(9), 145, (2013) (in Russian) [О.А. Денисова, О.А. Скалдин Электротехнические и информационные комплексы и системы. 4(9), 145, (2013).]
11.
O.A. Baimakova, O.A. Skaldin, A.N. Chuvyrov. Mol. Cryst. Liq. Cryst. 265, 299 (1995).
12.
A.P. Krekhov, O.A. Skaldin, A.N. Chuvyrov. Mol. Cryst. Liq. Cryst. 212, 245 (1992).
13.
K.V. Kondratenko, M.M. Farztdinov, A.N. Chuvyrov. Solid state physics 17(3), 795 (1975) (in Russian) [В.К. Кондратенко, М.М. Фарзтдинов, А.Н. Чувыров. ФТТ 17(3), 795 (1975).]
14.
S. Chandrasekhar. Liquid crystals. Mir, M. (1980). 344 p. (in Russian) [С. Чандрасекар. Жидкие кристаллы. Мир, М. (1980). 344 с]
15.
A.P. Krekhov, O.A. Skaldin. Solid state physics 32(6), 1882 (1990) (in Russian) [А.П. Крехов, О.А. Скалдин. ФТТ 32(6), 1882 (1990).]
16.
A.I. Derzhanski, A.G. Petrov and M.D. Mitov. J.de Phys. (France), 39, 273 (1978).
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1.
Денисова О.А., EUROPEAN RESEARCH, 22-26 (2016).
2.
Денисова О.А., Абрамишвили Р.Л., EUROPEAN RESEARCH, 21-25 (2016).
3.
Абрамишвили Р.Л., НАУЧНЫЕ ДОСТИЖЕНИЯ И ОТКРЫТИЯ СОВРЕМЕННОЙ МОЛОДЁЖИ, 100-102 (2017).
4.
Денисова О.А., Научный вестник, 194-207 (2017).
5.
Денисова О.А., Скалдин О.А., Письма о материалах 7(2 (26)), 141-145 (2017).
6.
Денисова О.А., Жидкие кристаллы и их практическое использование 17(2), 14-20 (2017).