中国物理B ›› 2019, Vol. 28 ›› Issue (3): 34209-034209.doi: 10.1088/1674-1056/28/3/034209

• ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS • 上一篇    下一篇

Improved dielectric and electro-optical parameters of nematic liquid crystal doped with magnetic nanoparticles

Geeta Yadav, Govind Pathak, Kaushlendra Agrahari, Mahendra Kumar, Mohd Sajid Khan, V S Chandel, Rajiv Manohar   

  1. Liquid Crystal Research Laboratory, Department of Physics, University of Lucknow, Lucknow 226007, India
  • 收稿日期:2018-10-07 修回日期:2019-01-23 出版日期:2019-03-05 发布日期:2019-03-05
  • 通讯作者: Rajiv Manohar E-mail:rajiv.manohar@gmail.com

Improved dielectric and electro-optical parameters of nematic liquid crystal doped with magnetic nanoparticles

Geeta Yadav, Govind Pathak, Kaushlendra Agrahari, Mahendra Kumar, Mohd Sajid Khan, V S Chandel, Rajiv Manohar   

  1. Liquid Crystal Research Laboratory, Department of Physics, University of Lucknow, Lucknow 226007, India
  • Received:2018-10-07 Revised:2019-01-23 Online:2019-03-05 Published:2019-03-05
  • Contact: Rajiv Manohar E-mail:rajiv.manohar@gmail.com

摘要:

This study investigates the effect of magnetic nanoparticles (NPs) on the weakly polar nematic liquid crystal (NLC). Different parameters of dielectric data were measured for both the homeotropic and planar aligned samples as a function of frequency and temperature and the substantial changes have been noticed for the doped systems. Dielectric permittivity has been increased after the dispersion of magnetic NPs in the pure NLC. Dielectric anisotropy has also been influenced by incorporating the magnetic NPs with the NLC molecules. These results were attributed to the dipole-dipole interaction between the magnetic nanoparticles and nematic liquid crystal molecules. Electro-optical study indicated the faster rise time and fall time of the doped systems as compare to pure NLC. Threshold voltage has been calculated and found to be decreased for the doped systems. Moreover, we have also calculated the rotational viscosity and the splay elastic constant for pure and the doped systems. Both the rotational viscosity and splay elastic constant of the doped systems are found to be considerably lower than those of pure NLC. Change in these properties has been explained on the basis of molecular disturbances created by the interaction between the magnetic nanoparticle and LC director. This study reveals that the inclusion of magnetic NPs in weakly polar NLC can be useful to enhance the basic properties of the weakly polar NLC and make it a promising material for many display applications.

关键词: magnetic nanoparticles, dielectric permittivity, response time, rotational viscosity

Abstract:

This study investigates the effect of magnetic nanoparticles (NPs) on the weakly polar nematic liquid crystal (NLC). Different parameters of dielectric data were measured for both the homeotropic and planar aligned samples as a function of frequency and temperature and the substantial changes have been noticed for the doped systems. Dielectric permittivity has been increased after the dispersion of magnetic NPs in the pure NLC. Dielectric anisotropy has also been influenced by incorporating the magnetic NPs with the NLC molecules. These results were attributed to the dipole-dipole interaction between the magnetic nanoparticles and nematic liquid crystal molecules. Electro-optical study indicated the faster rise time and fall time of the doped systems as compare to pure NLC. Threshold voltage has been calculated and found to be decreased for the doped systems. Moreover, we have also calculated the rotational viscosity and the splay elastic constant for pure and the doped systems. Both the rotational viscosity and splay elastic constant of the doped systems are found to be considerably lower than those of pure NLC. Change in these properties has been explained on the basis of molecular disturbances created by the interaction between the magnetic nanoparticle and LC director. This study reveals that the inclusion of magnetic NPs in weakly polar NLC can be useful to enhance the basic properties of the weakly polar NLC and make it a promising material for many display applications.

Key words: magnetic nanoparticles, dielectric permittivity, response time, rotational viscosity

中图分类号:  (Liquid crystals)

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