The Effect of the Size of BaTiO<sub>3</sub>Nanoparticles on the Electro-Optic Properties of Nematic Liquid Crystals

The electro-optic and dielectric properties of barium titanate, BaTiO 3 , nanoparticle (NP) doped nematic and ferroelectric liquid crystal materials were examined with respect to different size and concentration of the NPs. Smaller size paraelectric NPs (≈80nm) are compared to larger, ferroelectric NPs (≈240nm). It is found that for concentrations larger than 0.5vol% the ferroelectric NPs exhibit an increasing effect on the electro-optic response of the nematic liquid crystal, which is demonstrated by the enhancement of the dielectric anisotropy. This could be induced by the coupling of the electrical dipole moments in the spherical NPs with the LC director field. The electro-optical properties of the SmC* phase, like tilt angle Θ, switching time and spontaneous polarisation are found to be independent of the concentration and size of the NPs. The rotational viscosity calculated from response times, polarization reversal current and dielectric properties is comparable for all three methods employed and practically independent of particle concentration and size. The relaxation frequency of the Goldstone mode is higher in the ferroelectric NPs suspensions of 2.0vol% as compared to the smaller paraelectric NPs.

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“…. 10 This is of predominant interest for LC device applications since any reduction of V th can lead to a reduction of the power consumption.…”

Section: Reznikov Et Al Have Shown That a Low Concentration Of Ferromentioning

confidence: 99%

“…This is often achieved by coating the surface with monomolecular organic materials, surfactants (stabiliser), or ligands. For instance, oleic acid, 7,10,17,20,21,[24][25][26][27] selenium docosane 28 and dodecylbenzenesulphonic acid 29,30 have been widely utilized for the coating of NPs.…”

Section: Reznikov Et Al Have Shown That a Low Concentration Of Ferromentioning

confidence: 99%

A comparison between size dependent paraelectric and ferroelectric BaTiO3 nanoparticle doped nematic and ferroelectric liquid crystals

Al-Zangana

Turner

Dierking

2017

Journal of Applied Physics

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“…j and L (2) j are the geometric functions of the inner and outer ellipsoids [33], V is the total volume of the particle including the surfactant layer, and f is the ratio of the volume of the gold core relative to V . {1,2,m} are the dielectric permittivities of the gold core, surfactant and surrounding material, respectively.…”

Section: Appendix: Nanoparticle Modelmentioning

confidence: 99%

“…For example, ferroelectric nanoparticles have been shown to decrease the Fréedericksz threshold and increase the birefringence of nematics [2,3]. Similarly, ferromagnetic nanoparticles have been used to increase the sensitivity of the host liquid crystals to an applied magnetic field [4,5].…”

Section: Introductionmentioning

confidence: 99%

Gold nanoparticle liquid crystal composites as a tunable nonlinear medium

2014

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We investigate the nonlinearity of a liquid crystal cell doped with gold nanoparticles by considering their selective absorption. Such nonlinearities are promising for optical processing applications and optical limiters. Systems displaying thermal nonlinearities are particularly attractive as the maximum nonlinearity may occur in the absence of an applied field and additionally this nonlinearity can be controlled by the reorientation of the liquid crystal. We show that there exists a theoretical optimum concentration of absorbers, which maximizes the nonlinearity. Further we show that the nonlinearity of the system can be tuned by the reorientation of the liquid crystal host, with the nonlinearity decreasing from 9×10 −5 cm 2 W −1 to zero by the application of a magnetic field of the order of 0.01 Tesla. This allows a fine control of the diffraction efficiency and, in principle, many other nonlinear effects.

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“…It has been already reported that in the optical spectrum a hybrid LC and nanoparticle (NP) mixture, with a low concentration of ferroelectric NPs, can improve the birefringence of the material. [12][13][14][15] Doping of the LC with NPs, with size between 10-100 nm, can lead to significant increase of the dielectric anisotropy and of the birefringence of the suspension without disturbing the LC alignment. The enhancement of LC parameters is caused by the ferroelectricity of NPs, which produces large dipole moments, and thus large electric fields between the NPs.…”

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confidence: 99%

Refractive indices and birefringence of hybrid liquid crystal - nanoparticles composite materials in the terahertz region

et al. 2015

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We show that a hybrid LC-ferroelectric nanoparticle suspension of liquid crystal E7 doped with BaTiO3 nanoparticles leads to 10% increase in birefringence in the THz region of spectrum as compared to pure E7. Doped liquid crystals can be used to increase performance of THz modulators and waveplates. BaTiO3 nanoparticles used in the mixture were synthesised with the sol gel technique, and their refractive index has been measured in THz in powder form and in solution.

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The Effect of the Size of BaTiO₃Nanoparticles on the Electro-Optic Properties of Nematic Liquid Crystals

Cited by 23 publications

References 18 publications

A comparison between size dependent paraelectric and ferroelectric BaTiO3 nanoparticle doped nematic and ferroelectric liquid crystals

A comparison between size dependent paraelectric and ferroelectric BaTiO3 nanoparticle doped nematic and ferroelectric liquid crystals

Gold nanoparticle liquid crystal composites as a tunable nonlinear medium

Refractive indices and birefringence of hybrid liquid crystal - nanoparticles composite materials in the terahertz region

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The Effect of the Size of BaTiO3Nanoparticles on the Electro-Optic Properties of Nematic Liquid Crystals

Cited by 23 publications

References 18 publications

A comparison between size dependent paraelectric and ferroelectric BaTiO3 nanoparticle doped nematic and ferroelectric liquid crystals

A comparison between size dependent paraelectric and ferroelectric BaTiO3 nanoparticle doped nematic and ferroelectric liquid crystals

Gold nanoparticle liquid crystal composites as a tunable nonlinear medium

Refractive indices and birefringence of hybrid liquid crystal - nanoparticles composite materials in the terahertz region

Contact Info

Product

Resources

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The Effect of the Size of BaTiO₃Nanoparticles on the Electro-Optic Properties of Nematic Liquid Crystals