Investigation of the phases and the nature of the corresponding phase transition of a chiral ferroelectric liquid crystalline compound

Investigation of the phases and the nature of the corresponding phase transition of a chiral ferroelectric liquid crystalline compound

Barnali Barman

Department of Physics, Seva Bharati Mahavidyalaya, Jhargram, West Bengal, India, 721507

Abstract

Liquid crystals offer an excellent platform for studying the nature of phase transitions by providing a rich variety of mesophase orderings [1]. In many cases, they occur in narrow temperature ranges, and the phase transitions between different mesophases can be either continuous or weakly first-order. The most commonly studied mesophases are nematic (N), smectic-A (SmA), smectic-C (SmC), and their chiral analogue,s such as N*, SmA*, and SmC* phases. This work mainly focuses on the characteristics of the N* to SmC* phase transition of a pure ferroelectric liquid crystalline (FLC) compound, namely QVE 8/5 [2, 3]. The textures are characteristics of the different phases. For the studied compound, the characteristic textures corresponding to the N* and SmC* phases have been detected. The optical transmission method [ 4, 5] has been used in order to investigate the N* to SmC* phase transition. The temperature variation of the transmitted intensity for the compounds QVE 8/5 have been measured for both planar and homeotropic alignments of the molecules. The critical behaviour of the N* to SmC* phase transition has also been investigated. The extracted critical exponent (α') of the investigated compound was found to be less than 0.5, which implies the second-order nature of the N*-SmC* phase transition corresponding to the studied FLC compound.

References

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