Dielectric Relaxation in Nematic and Isotropic Phases of 4-(trans-4'-n-Propylcyclohexyl) isothiocyanatobenzene

1994 ◽  
Vol 49 (11) ◽  
pp. 1077-1080 ◽  
Author(s):  
J. Jadżyn ◽  
L. Hellemans ◽  
M. Stockhausen ◽  
C. Legrand ◽  
G. Czechowski
Keyword(s):  
Electric Field ◽  
Dielectric Relaxation ◽  
Nematic Phase ◽  
Liquid Crystalline ◽  
Frequency Region ◽  
Relaxation Processes ◽  
Phase Measurements ◽  
Field Parallel ◽  
Electric Field Parallel ◽  
Relaxation Study

Abstract The results o f a dielectric relaxation study (in the frequency region from about 1 kHz to 1 GHz) of the liquid crystalline title com pound (C3H7-Cyhx-Ph-NCS , 3-CHBT) in the isotropic and the nematic phase (measurements with electric field parallel to alignment) are presented. The spectra of both phases can be described by two relaxation processes of Debye-type, possibly related to rotation around the long and short molecular axes.

scholarly journals Liquid-Crystalline Curvature Electricity: The Bending Mode of MBBA

1972 ◽  
Vol 27 (2) ◽  
pp. 277-280 ◽  
Author(s):  
D. Schmidt ◽  
M. Schadt ◽  
W. Helfrich
Keyword(s):  
Electric Field ◽  
Liquid Crystalline ◽  
Room Temperature ◽  
Field Parallel ◽  
Electric Field Parallel ◽  
Bending Mode ◽  
Crystalline Curvature

AbstractMeasurements are reported which show that the room-temperature nematic MBBA can be deformed by means of curvature electricity if it is contained in a thin sandwich cell with the electric field parallel and the unique axis normal to the bounding walls. Meyer's coefficient e33 was determined to be 4 · 10-5 dyne1/2 at room temperature; and its sign was found to be positive.

scholarly journals Квазистационарные процессы диэлектрической релаксации в тонких поликристаллических пленках PZT

2020 ◽  
Vol 62 (10) ◽  
pp. 1665
Author(s):  
В.В. Иванов ◽  
Е.Н. Голубева ◽  
О.Н. Сергеева ◽  
Г.М. Некрасова ◽  
И.П. Пронин ◽  
...  
Keyword(s):  
Electric Field ◽  
Dielectric Relaxation ◽  
External Electric Field ◽  
Annealing Temperature ◽  
Relaxation Times ◽  
Polarization Vector ◽  
Silicon Substrates ◽  
Relaxation Processes ◽  
Pzt Films

In this work, relaxation processes in polycrystalline PZT films formed on silicon substrates with a quasistatic change in the external electric field are studied. It is shown that dielectric relaxation is characterized by at least three relaxation times, which depend on the direction of self-polarization vector in the film, the magnitude of the polarizing field, and also on the annealing temperature of the PZT films.

Dielectric Behaviour of 1-(4-Isothiocyanatophenyl)-2-(4-hexyl- bicyclo[2,2,2]octane-1)ethane in Nematic and Isotropic Phases

1996 ◽  
Vol 51 (8) ◽  
pp. 933-938 ◽  
Author(s):  
J. Jadżyn ◽  
C. Legrand ◽  
P. Kędziora ◽  
B. Żywucki ◽  
G. Czechowski ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Relaxation Time ◽  
Liquid Crystal ◽  
Order Parameter ◽  
Nematic Phase ◽  
Frequency Region ◽  
Relaxation Processes ◽  
Short Axis ◽  
Electric Permittivity ◽  
Orientation Axis

Abstract Static and dynamic investigations of the dielectric properties of the liquid crystal 1-(4-isothio-cyanatophenyl)-2-(4-hexyl-bicyclo[2,2,2]octane-1)ethane in the nematic and isotropic phases have been carried out in the frequency region from 1 kHz to 1 GHz. Two relaxation processes, described by the Debye functions, have been observed not only in the isotropic but also in the nematic phase, when the measurements of the electric permittivity vs. frequency have been made parallel to the orientation axis of liquid crystal. These processes are related to the rotation of the permanent dipole moment around two main molecular axes. The height of the potential barrier which hinders the rotation of the liquid crystal molecule around the short axis in the ordered nematic phase and the order parameter of the liquid crystal investigated have been estimated on the basis of the relaxation time values in the nematic and isotropic phases.

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