Nimet Yilmaz Canli

Molecular orientation of nickel phthalocyanine doped nematic liquid crystal composite under magnetic field

ABSTRACT The electrical and dielectric properties of the nematic liquid crystal (E63) and Nickel Phthalocyanine (NiPc) doped E63 composite have been investigated by dielectric spectroscopy under 0–0.4 T magnetic field. It has been observed that NiPc doping and external magnetic field, B decrease threshold voltage. Moreover, conductivity of the composite has an increasing tendency with magnetic field. Furthermore, a significant decrease in relaxation frequency with B has been interpreted as the simplification of molecular orientation. Hence, NiPc doping enhances the magnetic sensitivity of E63 and increases molecular orientation ability and conductivity.

The impact of NiPc additive and laser light dielectric properties of E63 nematic liquid crystal

ABSTRACT In this work, the electrical properties of the pure nematic liquid crystal (E63) and different concentrations Nickel Phthalocyanine (NiPc) doped (E63+1%NiPc, E63+3%NiPc and E63+5%NiPc) E63 have been investigated by means of dielectric spectroscopy measurements under laser light illumination. The variations of the real () and imaginary () parts of dielectric constant with frequency have been studied. According to versus voltage graphics, threshold voltage, Vth has been calculated. It has been observed that while NiPc doping increases the Vth, the application of laser light has a remarkable decreasing effect on threshold voltage, Vth. The absorption coefficients, , and relaxation times, , have also been calculated for determining the relaxation mechanism. It has been revealed that the relaxation type of these materials is nearly-Debye type regardless of the laser illumination. Moreover, the dielectric strength has been analysed both Debye and Cole-Cole models. Furthermore, conductivity mechanisms of these composites under dark and laser illumination have been investigated for four frequency regions. It has been shown that conductivity mechanism of the composites are not affected by application of laser light above .

Chiral Liquid Crystal-Based Sensor for the Detection of Low Humidity

The humidity sensing capability of a film of (S)-5-octyloxy-2-[{4-(2-methylbuthoxy)-phenylimino}-methyl]-phenol liquid crystal (LC) was studied. The experimental results show that LC thin film offers a promising perspective as a sensing material for the detection of relatively low humidity levels at even room temperature. It was observed that the operating temperature has a considerable effect on humidity sensing performance of the sensor. A comparison of kinetic models applied to the adsorption of water molecules on the LC film was evaluated for the Ritchie and Elovich kinetic models. Linear regression analysis results show that Elovich equation provides the best correlation for the water molecule adsorption processes.