(α,η) phase diagrams in tilted chiral smectics

• Published in: Physica. B, Condensed matter Condensed matter, 2013-02, Vol.410, p.162-169
• Main Authors: Rjili, M., Marcerou, J.P., Gharbi, A., Othman, T.
• Format: Article
• Language: English
• Subjects: Condensed matter; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Continuum theory; Density; Dielectric, piezoelectric, ferroelectric and antiferroelectric materials; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Ferroelectric materials; Ferroelectricity; Free energy; Liquid crystals; Liquids and liquid crystals; Mathematical analysis; Optimization; Phase diagram; Phase diagrams; Phase transition; Physics; Specific phase transitions; Tilted chiral smectics; Transitions in liquid crystals
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2012.11.011

The polymorphism of tilted chiral smectics liquid crystals is incredibly rich and encompasses many subphases such as SmCA⁎; SmCFi1⁎; SmCFi2⁎; SmC⁎; SmCα⁎. The continuum theory established by Marcerou (2010) [1] is used to derive an expression for the free energy density of those subphases. The minimization of this free energy is obtained through a combination of analytical and numerical methods. It leads to a phase diagram built in the (α,η) plane where α is local angular parameter and η describes the variation of the temperature. From this graphical representation, many experimentally observed phase sequences of ferroelectric liquid crystals can be explained, even them including subphases which were recently observed like the SmC5⁎ and the SmC6⁎ ones. However, it should be emphasized that the details of predicted phase diagram are strongly dependent on the compound studied.