Orientational order parameter-II - A birefringence study

P. Pardhasaradhi, C. S.V.S. Murthy, J. Lalitha Kumar, P. V.Datta Prasad, M. Srinivasulu, V. G.K.M. Pisipati

Research output: Contribution to journalArticle

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Abstract

Different techniques are available for the estimation of order parameter in the nematic phase of liquid crystals. However, most of these methods are not applicable to Cholesteric and smectic phases and therefore, the experimental data regarding the order parameter in these phases are hardly available. Measurement results of birefringence and refractive index of liquid-crystalline N-(p-n-pentyloxybenzylidene)-p-n-pentylaniline, 5O.5, N-(p-n-pentylbenzylidene)- p-n-pentylaniline, 5.5, N-(p-n-pentylbenzylidene)-p-n-pentyloxyaniline, 5.O5, and N-(p-n-hexyloxybenzylidene)-p-n-pentyloxyaniline, 6O.O5, were presented. Using these data, the polarizability anisotropy was calculated for both Vuks and Neugebauer local field models. Polarizabilities calculated in this way were applied to determine δα(polarizability anisotropy in the case of perfect orientation) using either Haller's and/or Subramhanyam's normalization procedures. Further, the polarisability anisotropy in the perfect order was calculated theoretically using the θ-function model developed by Lippincott et al. These procedures enabled the calculation of the orientation order parameter. Polarizabilities calculated using both local field models and from θ-function model developed by Lippincott et al. have been compared. The values of polarizability anisotropy for both local electric field models differ significantly. No criterion is known to decide which value is correct. To avoid the determination of uncertain xi and δαvalues considering different local field models, a simple procedure developed by Kuczynski et al. was used for evaluation of S, based solely on birefringence measurement. This procedure gave very reasonable results.

Original languageEnglish
Pages (from-to)1211591-1321602
Number of pages110012
JournalMolecular Crystals and Liquid Crystals
Volume511
DOIs
Publication statusPublished - 01-09-2009

Fingerprint

Birefringence
birefringence
Anisotropy
anisotropy
Liquid Crystals
Liquid crystals
Refractive index
liquid crystals
Electric fields
refractivity
Crystalline materials
electric fields
evaluation
Liquids
liquids

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Pardhasaradhi, P., Murthy, C. S. V. S., Kumar, J. L., Prasad, P. V. D., Srinivasulu, M., & Pisipati, V. G. K. M. (2009). Orientational order parameter-II - A birefringence study. Molecular Crystals and Liquid Crystals, 511, 1211591-1321602. https://doi.org/10.1080/15421400903053644
Pardhasaradhi, P. ; Murthy, C. S.V.S. ; Kumar, J. Lalitha ; Prasad, P. V.Datta ; Srinivasulu, M. ; Pisipati, V. G.K.M. / Orientational order parameter-II - A birefringence study. In: Molecular Crystals and Liquid Crystals. 2009 ; Vol. 511. pp. 1211591-1321602.
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Pardhasaradhi, P, Murthy, CSVS, Kumar, JL, Prasad, PVD, Srinivasulu, M & Pisipati, VGKM 2009, 'Orientational order parameter-II - A birefringence study', Molecular Crystals and Liquid Crystals, vol. 511, pp. 1211591-1321602. https://doi.org/10.1080/15421400903053644

Orientational order parameter-II - A birefringence study. / Pardhasaradhi, P.; Murthy, C. S.V.S.; Kumar, J. Lalitha; Prasad, P. V.Datta; Srinivasulu, M.; Pisipati, V. G.K.M.

In: Molecular Crystals and Liquid Crystals, Vol. 511, 01.09.2009, p. 1211591-1321602.

Research output: Contribution to journalArticle

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AU - Pardhasaradhi, P.

AU - Murthy, C. S.V.S.

AU - Kumar, J. Lalitha

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AU - Pisipati, V. G.K.M.

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Pardhasaradhi P, Murthy CSVS, Kumar JL, Prasad PVD, Srinivasulu M, Pisipati VGKM. Orientational order parameter-II - A birefringence study. Molecular Crystals and Liquid Crystals. 2009 Sep 1;511:1211591-1321602. https://doi.org/10.1080/15421400903053644