The variation of refractive indices with temperature of three pure nematogenic compounds 5OCB, CPHB and 6CHBT were studied experimentally using thin prism technique. The refractive indices no and ne were measured using 633 nm lines from a HeNe laser. A modied four-parameter model was taken which is based on the Vuks equation describing the eect of temperature on the refractive indices of liquid crystals. In this paper we report the variation of refractive indices of these three liquid crystals with temperature, using the thin prism method. The variation in birefringence was determined experimentally. The variation in refractive indices and birefringence were also tted theoretically using the modied Vuks equation. On comparison, the theoretically tted values show close agreement with the experimental values.

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Phase transition and some physical properties of binary mixtures of two nematogenic compounds showing induced smectic phase, Phase Transitions: A Multinational Journal, 85:1-2, 85-95,The binary mixtures of nematogenic compounds 4-n-pentyl phenyl 4-n 0 -hexyloxy benzoate (ME6O.5) and 4-cyanophenyl 4-pentyl benzoate (CPPB) show the presence of induced smectic phase. In this article, we report the phase diagram and the results of refractive index, density, static dielectric permittivity and X-ray diffraction measurements of different binary mixtures of (ME6O.5 þ CPPB) throughout the entire composition range. The density and refractive index values have been analysed to obtain orientational order parameters. The various physical properties of the system have been discussed on the basis of the phase diagram.