Orientational order parameter of liquid crystalline mixtures – A birefringence study
https://doi.org/10.17586/2220-8054-2018-9-6-735-740
Abstract
The orientational order parameter is one of the most important material parameters of nematic phase. In the present work, the phase transition temperatures of the mesogenic mixtures are measured by using a polarizing optical microscope. The birefringence in nematic phase is estimated by measuring ordinary and extraordinary refractive indices. The birefringence is also measured by measuring the diameter of Newton’s rings at various temperatures in nematic phase. The orientational order parameter is evaluated by using the birefringence data obtained in the above two methods. The orientation order parameter can be enhanced by the dispersion of different nanoparticles in the liquid crystal matrix.
Keywords
Liquid crystalline mesogens,
orientational order parameter,
birefringence,
refractive index,
Newtons rings
Supporting agencies: Authors express their thanks to the Department of Physics, Ghousia College of Engineering, Ramanagaram for providing laboratory facilities. The authors are thankful to Dr. C.M. Yellamagad and Dr. D.S. ShankarRao for providing liquid crystalline compounds to carry out the present studies. The financial support rendered by the VTU Belgaum under VTU research grant scheme for the research project [No. VTU/Aca/2011-12/A-9/750] is gratefully acknowledged.
About the Authors
. Shahina
Department of Physics, Ghousia College of Engineering
India
India
Ramanagara., Karnataka
C. M. Subhan
Department of Physics, Shri Shirdi Sai Institute of Science and Engineering
India
India
Vadiyampeta, Anantapurmu, Andhra Pradesh
S. Rangappa
Department of Physics, BIT
India
India
Bangalore, Karnataka
K. Fakruddin
Department of Physics, Ghousia College of Engineering
India
India
Ramanagara., Karnataka
References
1. Kato T., Mizoshita N., Kishimoto K. Functional liquid-crystalline assemblies: self-organized soft materials. Angew Chem. Int. Ed. Engl., 2005, 45 (1), P. 38–68.
2. Goodby J.W., Saez I.M., et al. Transmission and amplification of information and properties in nanostructured liquid crystal. Angew Chem. Int. Ed. Engl., 2008, 47 (15), P. 2754–2787.
3. Shiraishi Y., Toshima N., et al. Frequency modulation response of a liquid-crystal electro-optic device doped with nanoparticles. Appl. Phys. Lett., 2002, 81 (15), P. 2845–2847.
4. de Gennes P.G., Prost J. The Physics of Liquid Crystals, Clarendon Press, Oxford, 1998.
5. Obadovic D.Z., Stojanovic M., et al. Study of Binary Cholesteric Liquid Crystalline Mixtures Doped with Some Chiral Nonmesogenic Estradiol Derivatives. Mol. Cryst. Liq. Cryst., 2011, 547, P. 1736–1743.
6. Eren San S., Mustafa Okutan, Oguz Koysal, Yusuf Yerli. Carbon Nanoparticles in Nematic Liquid Crystals. Chin. Phys. Lett., 2008, 25 (1), P. 212–215.
7. Goel P., Arora M., Biradar A.M. Electro-optic switching in iron oxide nanoparticle embedded paramagnetic chiral liquid crystal via magneto-electric coupling. J. App. Phy., 2014, 115, P. 124905.
8. Silva J.B., Brito W.D., Mohallem N.D.S. Influence of heat treatment on cobalt ferrite ceramic powders. Material Sci. Eng. B, 2004, 112, P. 182–187.
9. Sun S., Murray C.B., et al. Monodisperse FePt Nanoparticles and Ferromagnetic FePt Nano Crystal Superlattices. Science, 2000, 287, P. 1989–1992.
10. Pankhurst Q.A., Connolly J., Jones S.K., Dobson J. Applications of magnetic nanoparticles in biomedicine. J. Phys. D: Appl. Phys., 2003, 36, P. 167–181.
11. Ito A., Shinkai M., Honda H., Kobayashi T. Medical application of functionalized magnetic nanoparticles. J. Bio. Sci Bio. Eng., 2005, 100 (1), P. 1–11.
12. Meng X., Li H., et al. Mossbauer study of cobalt ferrite nanocrystals substituted with rare-earth Y3+ ions. J. Magn. Magn. Meter., 2009, 321, P. 1155–1158.
13. Toh C.L., Xu J., He C. Synthesis and characterisation of main-chain hydrogen-bonded supramolecular liquid crystalline complexes formed by azo-containing compounds. Liq. Cryst., 2008, 35 (3), P. 241–251.
14. Haller I., Huggins H.A., Lilienthal H.R., McGuire T.R. Order – Related Properties of Some Nematic Liquids. J. Phys. Chem., 1973, 77 (7), P. 950–954.
15. Fakruddin K., JeevanKumar R., DattaPrasad P.V., Pisipati V.G.K.M. Orientational Order Parameter – 1 A Birefringence Study. Mol. Cryst. Liq. Cryst., 2009, 511, P. 133–145.
16. Subhan C.M., Jeevan Kumar R., et al. An Optical Study to Estimate Orientational Order Parameter on Some Benzylidene amino phenyl benzoate Liquid Crystals. Acta Physica Polonica A, 2016, 129 (3), P. 284–288.
17. Narasimhamurthy G.K., Subhan C.M., et al. Orientational order parameter of some CBOnO.m liquid crystalline compounds – an optical study. Mol. Cryst. Liq. Cryst., 2016, 641, P. 25–36.
18. Kuczynski W., Zywucki B., Malecki J. Determination of Orientational Order Parameter in Various Liquid-Crystalline Phases. Mol. Cryst. Liq. Cryst., 2002, 381, P. 1–19.
19. Zywucki B.J., Kuczynski W. The Orientational Order in Nematic Liquid Crystals From Birefringence Measurements. Dielectr. Electr. Insul., 2001, 8 (3), P. 512–515.
20. Ramakrishna Nanchara Rao M., Datta Prasad P. V., Pisipati V.G.K.M., MadhaviLatha D. An Optical study on Orientational order parameter and Molecular Polarizability in Benzylidene Anilines. Solid State Phenomena, 2012, 181–182, P. 102–105.
21. Subramhanyam H.S., Krishnamurti D. Polarization Field and Molecular Order in Nematic Liquid Crystals. Mol. Cryst. Liq. Cryst., 1973, 22, P. 239–248.
22. Pardhasaradhi P., Datta Prasad P.V., et al. Orientational order parameter studies in two symmetric dimeric liquid crystals – an optical study. Phase Transitions, 2012, 85 (12), P. 1031–1044.
Review
For citations:
Shahina , Subhan C.M., Rangappa S., Fakruddin K. Orientational order parameter of liquid crystalline mixtures – A birefringence study. Nanosystems: Physics, Chemistry, Mathematics. 2018;9(6):735–740. https://doi.org/10.17586/2220-8054-2018-9-6-735-740
Views:
2
Email this article 