K. R. K. Rao

Density and Ultrasonic Velocity Measurements in Hexyloxybenzylidene Phenylazoaniline

Abstract The temperature variation of density and ultrasonic velocity of the liquid crystal hexyloxybenzylidene phenylazoaniline are reported. The density across the smectic A—smectic B transition is more predominant than the other transitions. The density variation with temperature and the calculated thermal expansion coefficients suggest that the transitions isotropic liquid—nematic, nematic—smectic A and smectic A—smectic B are of first order. Anomalous behaviour of ultrasonic velocity is observed across the isotropic liquid—nematic transition and prominent dips in velocity are observed at the nematic—smectic A and smectic A—smectic B transitions. The adiabatic compressibility (β ad ) Rao number (R a ) and molar compressibility (B) are estimated using the experimental density and ultrasonic velocity.

Phase transition studies in p-n-nonyloxybenzoic acid

Abstract Phase transitions of the liquid crystal p-n-nonyloxybenzoic acid have been investigated with density and ultrasonic velocity measurements. The variation of density with temperature confirms that the isotropic-nematic and nematic-smectic C transitions are of first order. All the phase transitions are confirmed by the variation of ultrasonic velocity with temperature. The adiabatic compressibility (βad), and Rao number (Rn) are also estimated.

Magnetic susceptibility studies of the liquid crystal N-(p-n-pentyloxybenzylidene) p-n-butylaniline

Abstract The temperature variation of the magnetic susceptibility (χ) of N-(p-n-pentyloxybenzylidene) p-n-butylaniline is reported in the isotropic, nematic, smectic A, smectic AG and smectic G phases. Abrupt changes in χand Δχ are observed at various phase transitions. An unusual decrease in χ with decreasing temperature is observed during the smectic A-smectic AG and smectic AG-smectic G transitions.

Electric and magnetic field effects in the nematic phase of N-(p-n-pentyloxybenzylidene) p-n-butylaniline

Abstract The molecular alignment in the nematic phase of N-(p-n-pentyloxybenzylidene) p-n-butylaniline (PBBA) in the presence of electric and magnetic fields is investigated by measuring the dielectric constant at 1 MHz. The relative effectiveness of electric and magnetic fields in the nematic phase of PBBA is discussed.