Relaxation processes and charge transport across liquid crystal-electrode interface

Abstract. Multiferroics stable in morphological parameters has been created by introducing ferromagnetic (Fe 2 O 3 ) and ferroelectric (LiNbO 3 ) nanoparticles with the concentration 0.3 wt.% into nematic liquid crystal 6СНВТ. Being based on the analysis of photos obtained in nonpolarized light of optical microscope, it has been shown that the average sizes of irregular geometric shape of aggregates of Fe 2 O 3 nanoparticles range unities of micrometers and are one order higher than spherical aggregates of LiNbO 3 nanoparticles. It has been shown that low-frequency dispersion of components for the complex permittivity is caused by near-electrode processes. The mechanism of this relaxation process has been ascertained, and its parameters for some of the samples have been determined. It has been shown that when introducing the nanoparticles the conductance of liquid crystal decreases, which may be caused by adsorption of ions (that carry charge through the liquid crystal) on the surface of the nanoparticles.

Section: The Impact Of Nanoparticles On the Dielectric Properties Of Nlcmentioning

confidence: 65%

Multiferroic based on nematic liquid crystal and nanoparticles

Koval’chuk¹

2016

“…Therefore, these large ε'quantities can be cosidered as the effective ones. In [19,20], we have also shown as the dispersion of ε' and ε'', which is caused by the influence of near-electrode processes, is described by the same relations that the dispersion in the bulk of samples (Debye dispersion, Cole-Cole dispersion, etc. ).…”

Section: Resultsmentioning

confidence: 89%

“…As we have shown in [19,20], these large ε' quantities are caused by inhomogeneous distribution of the electric field in the sample due to the impact of near-electrode processes. Therefore, these large ε'quantities can be cosidered as the effective ones.…”

Section: Resultsmentioning

confidence: 93%

Peculiarities of near-electrode relaxation processes in the polyethylene melt filled with graphite and carbon black

Kuryptya¹

2016

Abstract. By using the oscilloscope method within the frequency range 10 to 10 6 Hz at the temperature 492.1 K and pressure 11.31 MPa at the output of the single-screw extruder, the dielectric properties of the composite melt -linear low-density polyethylene + 20 wt.% of graphite + 10 wt.% of carbon black -have been investigated. It has been shown that in the whole frequency range, near-electrode processes significantly effect on charge transfer. For the frequencies less than 100 Hz, in the near-electrode area the conductance is provided with hopping movement of electrons. For the frequencies over 100 Hz, charge transfer occurs through the ion movement. It has been shown that the transfer of ions in the near-electrode area can be described using the relaxation process that, unlike the vast majority of processes described in the publications, meets the wellknown relations only in terms of the complex conductivity. It has been shown that, in the terms of the complex conductivity, this relaxation process can be approximated with Debye equation, as well as it has been estimated the relaxation time (8.5 ms) for this process. According to the parameters included in the Debye equation, it has been estimated the thickness of the near-electrode area (17 μm) and shown that it practically coincides with the sizes of graphite particles.

“…1 shows the frequency dependence of the real component of the complex permittivity ε′ of planar oriented: 6СНВТ (1), 6СНВТ+0.01 wt.% ANP (2), 6СНВТ+0.02 wt.% ANP (3) and 6СНВТ+0.1 wt.% ANP (4). From the analysis of the data obtained, it follows that the whole dielectric spectrum can be separated into three sections: A, B and C. In our previous studies [18,19] and in [20], it was shown that each of these sections characterizes different processes. Fig.…”

Section: …10mentioning

confidence: 88%

The non-linear dependence of 6СНВТ liquid crystal conductivity on the concentration of gold nanoparticles

Koval’chuk¹

2016

Abstract.Within the frequency range 10 -1 …106 Hz at the temperature 293 K, the effect of gold nanoparticles on the dielectric properties of the planar-oriented nematic liquid crystal 6СНВТ has been studied. The concentration of nanoparticles with the average diameter 3 to 5 nm was chosen as 0.01, 0.02 and 0.1 wt.%. It has been shown that for the frequencies less than 10 Hz, the dielectric properties of the samples can be described with the Debye dispersion. For the samples with the concentration of gold nanoparticles 0.1 wt.%, the time of relaxation has been estimated (4.7±0.5 s). It has been also shown that the conductivity of the liquid crystal depends non-linearly on the concentration of nanoparticles introduced into the liquid crystal. The greatest change in conductivity of the liquid crystal on the concentration of introduced gold nanoparticles has been obtained within the range of 0.01 to 0.02 wt.%. It has been assumed that the conductivity of 6СНВТ that depends non-linearly on the concentration of introduced gold nanoparticles is caused by the competing processes of ion desorption from the gold nanoparticles and of nanoparticle aggregation.