Macroscopic properties of smectic C-G liquid crystals

We discuss the macroscopic behavior of smectic C-G liquid crystals. Smectic C-G is the most general tilted smectic phase that is fluid in the layers. It is characterized by global C-1 symmetry. Consequently, it is ferroelectr ic; pyroelectric and piezoelectric, opening up a number of possible applica tions for such a phase. As smectic C-G-phase has a macroscopic hand duc to its structure, it is a natural candidate to explain the recent experimental observations of left and right-handed helices in a system composed of achi ral molecules. We also discuss critically to what extent smectic C-G could be important for liquid crystalline phases formed by banana-shaped molecule s. Phase transitions involving a smectic C-G phase and defects of its in-pl ane director are briefly discussed.