Abstract
The principal dielectric constants of the pentyl to octyl derivatives of 4′-n-alkyl-4-cyanobiphenyl have been measured as functions of temperature in their nematic and isotropic phases. All the compounds exhibit a strong positive dielectric anisotropy due to the presence of a large dipole moment along the major molecular axis. The principal dielectric constantsε ‖ andε ⊥ as well as the anisotropy Δε decrease with increasing alkyl chain length. The experimental value of\(\bar \in = \frac{1}{3}\) (ε‖+2ε⊥) decreases with decreasing temperature, and is throughout less than the extrapolated isotropic value, in conformity with the model of antiferroelectric short range order proposed by Madhusudana and Chandrasekhar.
Similar content being viewed by others
References
Derzhanski A and Perov A G 1971Phys. Lett. 34A 427
Gray G W, Harrison K J, Nash J A, Constant J, Hulme D S, Kirton J and Raynes E P 1973 ‘Liquid Crystals and Ordered Fluids’ Vol 2 eds J F Johnson and R S Porter (New York-London: Plenum Press) p 617
Gray G W 1975J. Physique 36 C1–337
de Jeu W H and Lathouwers Th W 1974Z. Naturforsch. 29 a 905
Karat P P and Madhusudana N V (to be published)
Leadbetter A J, Richardson R M and Colling C N 1975J. Physique 36 C1–37
Luckhurst G R and Poupko R 1975Mol. Phys. 29 1293
Lydon J E and Coakley C J 1975J. Physique 36 C1–45
Madhusudana N V and Chandrasekhar S 1973 Proc. Int. Conf. Liquid Crystals (Bangalore)Pramāna Suppl. 1 57
Minkin V I, Osipov O A and Zhdanov Yu A 1970Dipole Moments in Organic Chemistry (New York-London, Plenum Press) p. 91
Ratna B R, Vijaya M S, Shashidhar R and Sadashiva B K 1973 Proc. Int. Conf. Liquid Crystals (Bangalore)Pramāna Suppl. 1 69
Schadt M 1972J. Chem. Phys. 56 1494
Titov V V, Kovshev E I, Pavluchinko A I, Lazareva V T and Grebenkin M F 197J. Physique 36 C1-387
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Ratna, B.R., Shashidhar, R. Dielectric properties of 4′-n-alkyl-4-cyanobiphenyls in their nematic phases. Pramana - J. Phys. 6, 278–283 (1976). https://doi.org/10.1007/BF02872205
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02872205