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Phase transition studies in 50CB and 80CB
Author(s) -
Venkatacharyulu P.,
Gupta A. V. N.,
Rao J. V.,
Prasad K. S. R.,
Prasad N. V. L. N.
Publication year - 1989
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.2170240822
Subject(s) - compressibility , van der waals force , intermolecular force , isotropy , liquid crystal , thermodynamics , phase transition , adiabatic process , phase (matter) , van der waals equation , materials science , chemistry , physics , optics , molecule , organic chemistry , optoelectronics
Investigations on the temperature variation of specific volume and ultrasonic velocity are carried out to study the phase transitions in the liquid crystals 4′‐n‐Pentyloxy‐4‐Cyanobiphenyl (50CB) and 4′‐n‐Octyloxy‐4‐Cyanobiphenyl (80CB). From these studies various parameters like the adiabatic compressibility (β ad ), molar sound velocity or Rao number ( R n ), molar compressibility ( B ), Van der Waals constant ( b ) and the intermolecular free lengths ( L ) are estimated as a function of temperature in the isotropic as well as in the mesophases. Finally the variation of the order parameter with temperature in the nematic phase is studied and the results are discussed.