Induction of the smectic Ad phase in polar systems II. Role of steric effects in the smectic Ad phase induction

Binary mixtures in which one component is nCBB or its chiral analogue, and the second component is nCB, nOCB, n.CN, or one of their chiral analogues are studied by thermomicroscopy. The branched compounds induce the smectic A_d phase more strongly than unbranched compounds with the same alkyl chain length. The observed behaviour is discussed from the point of view of dimer formation. In all chiral systems, the TGB_A phase appears.