Abnormal switching behavior of nanoparticle composite systems

Abstract

We have investigated the properties of liquid crystals (LCs) doped with ZnO (8% Cu doped) nanoparticles. The electro-optic properties of LCs have changed with varying concentration of ZnO nanoparticles. The dielectric anisotropy obtained from the values of dielectric permittivity at 5 kHz in the nematic and smectic phases was found to increase with increasing concentration of nanoparticles in LCs. It has been established that the effect of nanoparticles on the dielectric anisotropy depends on the physical properties of LCs; the nanoparticle disturbs the orientation ordering of LC molecules. The nanoparticle also influences the switching behavior, splay elastic constant, rotational viscosity and threshold voltage of pure LCs. A small quantity of nanoparticles causes slight reduction of the splay elastic constant and rotational viscosity of LC cells.

Keywords:

• nanoparticle
• liquid crystal
• dielectric anisotropy
• switching
• splay elastic constant

Acknowledgements

The authors are sincerely thankful to ISRO for providing assistance in the RESPOND program in the form of the project entitled ‘Designing of SLMs based on nematic LCs doped with non-mesogenic molecules’. One of the authors (AKM) is thankful to UGC, New Delhi, for the third-year grant of Dr D.S. Kothari Post Doctoral Fellowship No. F.4.2/2006 (BSR)-13-234/2008(BSR).