Abstract

Dielectric properties and other physical properties such as electrical conductivity (AC) and relaxation time or activation energy have been studied for two systems pure LC [V]6,6, [V]7,6, [V]8,6, [V]6,7, [V]7,7 and [V]8,7 and their doped with silver nanoparticles. The results show the increasing in real dielectric permittivity I­ with increasing length terminal chain. So the real dielectric permittivity increasing with raising temperature. To compare between the values of (400) Hz and (4000) Hz we observe these values at the low frequency are larger than that in high frequency. Generally, one can see that the doping of Ag nano particles effectively reduced the permittivity of the LC materials with its large electric dipole moment. The electrical conductivity σ value for pure LC samples in general increases with increasing temperature. So we observed increasing of electrical conductivity values at high frequency. The time scale is discussed in terms of the Arrhenius plot. Generally, with increasing the temperature the time period that spends by molecules at the transition state will increase. The activation energy Ea values show the increase in the activation energy to the doped systems.

Highlights

  • The importance of liquid crystals lies in their extensive use in display devises, It is well known that liquid crystals are very sensitive to an electrical field

  • Our aim is to study some physical properties such as dielectric permittivity, electrical conductivity and relaxation time or activation energy for two systems pure LC [V]6,6, [V]7,6, [V]8,6, [V]6,7, [V]7,7 and [V]8,7 and their doped with silver nanoparticles

  • ; A is the area of the electrode in m2, which equal (0.001) m2 and t is the thickness of the specimen in m, which equal (12) μm. is the electrostatic capacity of the specimen in pf, R is the resistance of the specimen and

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Summary

Introduction

The importance of liquid crystals lies in their extensive use in display devises, It is well known that liquid crystals are very sensitive to an electrical field. This property allows their applications to displays and other optical devices technology [1,2,3,4,5]. The use of liquid crystals in different devises depends upon various properties owned by them like order parameter, dielectric permativity, dielectric anisotropy, birefringent behavior, optical transmittance, elastic constants etc [6]. The different mixtures of liquid crystals and their doped samples have gained growing interest These doped samples have emerging prospects regarding their applications in information processing [12]. All members of those two series exhibit an enantiotropic dimorphism smectic A (SmA), smectic C (SmC) and/ or nematic (N) phases

Experimental
Dielectric Permittivity Measurements
Preparation of Cells
Preparation of Samples
Preparation of Silver Nano Particles
Characterization of Silver Nano particles
XRD Analysis
Dielectric Permittivity Properties
Imaginary Dielectric Permittivity
Electrical Conductivity
Relaxation Time and Activation Energy
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