Order parameter and its critical exponent for some binary mixtures showing induced nematic phase

Abstract

Refractive index measurements as a function of temperature have been performed for an induced nematic binary system by means of thin prism technique. The temperature dependence of the birefringence (Δn) has been assessed from the measured refractive index data. A direct extrapolation method has been employed to determine the orientational order parameter for the investigated mixtures and the order parameter so obtained has also been compared with the mean field values. The Haller type fitting expression results in a relatively lower value of the order parameter critical exponent (β) compared to the theoretically predicted values. Therefore, a four-parameter power law expression, consistent with the mean field theory as well as the first-order character of the nematic–isotropic (N-I) phase transition have been used to explore the critical behavior of the order parameter near the N-I transition.

Keywords:

• binary mixture
• induced nematic phase
• orientational order parameter
• critical exponent

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Financial support from the Department of Science and Technology, New Delhi (Project No. SB/EMEQ-290/2013) is gratefully acknowledged.