Thermodynamic model to study the phase transition properties of Sm𝐶_A∗ phase in antiferroelectric Mesogen W-358 Series

Employing the thermodynamic model which is centred on Landau-de-Gennes theory, the electro-optical properties of the Sm𝐶_A∗ phase in antiferroelectric mesogen has been studied. The wave vector q, the polarisation vector P, and the couplings between these order parameters are used to express the system's free-energy density. The Landau coefficients involved in the free-energy density have been computed using experimental data of tilt angle and spontaneous polarisation in the Sm𝐶_A∗ phase of chiral compounds (6F2OBi and 3F5HBM6(S)). Theoretical and experimental data have been compared in investigations. (author)