Analysis of birefringence property of three different nematic liquid crystals dispersed with TiO 2 nanoparticles

Pathak, Govind; Katiyar, Rohit; Agrahari, Kaushlendra; Srivastava, Atul; Dąbrowski, R.; Garbat, K.; Manohar, Rajiv

doi:10.1016/j.opelre.2017.11.005

Cited by 61 publications

(14 citation statements)

References 36 publications

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“…The Δε of the LCs was defined as the difference between ε and ε ⊥ at a frequency of 1 kHz. The Δn of the LCs was derived with the phase retardation technique 5 . Figure 2a shows the POM images of the BNA-doped LC cells, where the cell rubbing direction was placed at 45° with respect to the transmission axes of the polarizer and analyzer.…”

Section: Methodsmentioning

confidence: 99%

Electro-optical effects of organic N-benzyl-2-methyl-4-nitroaniline dispersion in nematic liquid crystals

Selvaraj

Karthick

Brahadeeswaran

et al. 2020

Sci Rep

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The dispersion of organic N-benzyl-2-methyl-4-nitroaniline (BNA) in nematic liquid crystals (LCs) is studied. BNA doping decreases the threshold voltage of cell because of the reduced splay elastic constant and increased dielectric anisotropy of the LC mixture. When operated in the high voltage difference condition, the BNA-doped LC cell has a fall time that is five times faster than that of the pure one because of the decrements in the threshold voltage of the cell and rotational viscosity of the LC mixture. The additional restoring force induced by the BNA's spontaneous polarization electric field (SPEF) also assists to decrease the fall time of the LC cell. The decreased viscosity can be deduced from the decrements in phase transition temperature and associated order parameter of the LC mixture. Density functional theory calculation demonstrates that the BNA dopant strengthens the absorbance for blue light, enhances the molecular interaction energy and dipole moment, decreases the molecular energy gap, and thus increases the permittivity of the LC mixture. The calculation also shows that the increased dipole moment, polarizability, and polarizability anisotropy increase the dielectric anisotropy of the LC mixture, which agrees with the experimental results well. BNA doping has a promising application to the fields of LC devices and displays. Nematic liquid crystals (LCs) are extraordinarily responsive and optically uniaxial materials. Nematic LCs have been extensively used in diverse applications, such as optical nonlinearity, optical phase modulators, microdisplays, flat panel displays, optical antennas, and optical switching, due to their electro-optical property and other admirable features 1-5. LCs with a fast response are vital in removing motion blur in moving pictures and resolving cross-talk in 3D displays 6-9. The response time of LCs should be less than 3 ms to diminish motion blur and cross-talk. Several techniques have been proposed to resolve this issue, and they include tuning the viscosity of materials 10 , varying the anchoring energy 11 , changing the electrode shape and driving scheme 12 , changing the cell gap 13 , modifying the guest-host material 14 , and applying new switching modes 15. The improvements in the electro-optical properties of LCs with the dispersion of different gust entities were presented recently. For example, Y. Dai et al. demonstrated that the incorporation of γ-Fe 2 O 3 nanoparticles into LCs results in a response time of 4.75 ms with the application of the overdriving scheme, which is three times faster than pure LCs 16. A response time of around 4 ms was obtained with the addition of a small amount of dye to a polymer-dispersed liquid crystal (PDLC) or functionalized carbon nanotubes dispersed in optically isotropic LCs. However, in this case, the excellent response speed is valid only for operation at a relatively high voltage 17,18. Blue-phase LCs have a response time of 0.5 ms, but they still have drawbacks, such as hysteresis, high operation voltage, and narrow t...

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Section: Methodsmentioning

confidence: 99%

Electro-optical effects of organic N-benzyl-2-methyl-4-nitroaniline dispersion in nematic liquid crystals

Selvaraj

Karthick

Brahadeeswaran

et al. 2020

Sci Rep

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“…Anatase TiO 2 NPs used as a doped material in this study have spherical shape and particle size 20-24 nm [38,39]. These NPs have been purchased from Aldrich UK.…”

Section: Methodsmentioning

confidence: 99%

Effect of ion trapping behavior of TiO2 nanoparticles on different parameters of weakly polar nematic liquid crystal

et al. 2018

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In the present investigation, TiO 2 -doped weakly polar nematic liquid crystal (NLC) has been studied. This study mainly focuses on dielectric, electro-optical and optical properties of pure NLC and doped systems. Variation in different parameters like dielectric permittivity, dielectric loss, dielectric anisotropy and conductivity has been noticed. Permittivity of the doped system is almost the same as undoped system. With doping concentration, the ionic contribution to the dielectric loss as observed in low-frequency region has been suppressed and the shift in relaxation frequency toward higher frequency side has also been observed. The electrical conductivity and threshold voltage have been decreased with increasing concentration of nanoparticles (NPs). The continuous increase in dielectric anisotropy with increasing the concentration of NPs has also been observed. These results have been attributed to the trapping capability of free ions by TiO 2 NPs. Further, we focused on the study of photoluminescence (PL), UV absorbance and Fourier transformed infrared spectroscopy (FTIR) of pure and doped systems. The continuous increase in PL intensity without any shift in emission peak has been observed for doped systems. Enhancement in UV absorbance with increasing concentration of NPs has also been observed. The effect of NPs doping on molecular dynamics of NLC can be clearly seen by FTIR study. The results suggest that the TiO 2 NP-doped weakly polar NLC can have significant improved dielectric, electro-optical and optical properties. This makes the weakly polar NLC to be a potential candidate for many applications.

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“…Base precipitating agents such as KOH, NaOH, NH 4 OH, and K 2 CO 3 may then be added in drops with vigorous agitation for 3 h. The mixture is then allowed to settle, and the resultant solution is separated and dried at 100‐120 °C for 24 h. The dried sample is then calcined at appropriate temperature. This method was adopted by Pathak et al 105 . in their experiment to synthesize basic iron oxide nanoparticles (MAPAE@Fe 3 O 4 ).…”

Section: Biogenic Waste Derived Catalysts Modifications and Its Activmentioning

confidence: 99%

Effectiveness of biogenic waste‐derived heterogeneous catalysts and feedstock hybridization techniques in biodiesel production

Etim

Musonge

Eloka‐Eboka

2020

Biofuels Bioprod Bioref

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Biodiesel has the potential to contribute significantly to the elimination of the present global energy and climate change logjam, but its production and commercialization have been hindered by the diverse nature of the feedstocks used for production. This paper reviews the effectiveness of applying various types of crop and animal waste-derived catalysts together with innovative feedstock hybridization as an economically viable technique for biodiesel production. Feedstock challenges, availability, and sustainability for large-scale applications are addressed with a view to bridging the existing gaps. Challenges in the use of edible oils and algae oil sources and development remain, but the technique of feedstock hybridization appears to be very promising, innovative, and cost-effective for biodiesel production. The present state of biodiesel production could be improved by the application of simple and cost-effective technologies in the feedstock system. High free fatty acid (FFA) content is the major hurdle to the use of most oils, especially low-grade/advanced oil feedstocks, in biodiesel production. This could be addressed through technological application of feedstock hybrids and biogenic waste-derived heterogenous catalysts, and their biochemical modifications. Conventional technology for the large-scale application of inorganically derived catalysts in biodiesel production with various characteristic differences is presented. Heterogenous catalysts derived from biogenic wastes and their modification could be used to overcome associated problems with the use of inorganic catalysts in biodiesel production. Biogenic waste-derived heterogenous catalysts are renewable, available, eco-friendly, and cost-effective. Technological applications of heterogeneous catalysts derived from biogenic waste are outlined and reviewed, considering various materials and different modification techniques to identify appropriate options for scaling up development. This review also discusses fundamental considerations for the Review

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Analysis of birefringence property of three different nematic liquid crystals dispersed with TiO 2 nanoparticles

Cited by 61 publications

References 36 publications

Electro-optical effects of organic N-benzyl-2-methyl-4-nitroaniline dispersion in nematic liquid crystals

Electro-optical effects of organic N-benzyl-2-methyl-4-nitroaniline dispersion in nematic liquid crystals

Effect of ion trapping behavior of TiO2 nanoparticles on different parameters of weakly polar nematic liquid crystal

Effectiveness of biogenic waste‐derived heterogeneous catalysts and feedstock hybridization techniques in biodiesel production

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