N-S_A Transition First or Second Order: Tricritical Point (TCP) in N(p-n-pentyloxy benzylidene)p-n-alkyl anilines?

Abstract

The nature of the nematic-smectic A (NA) phase transition is discussed in the light of the available experimental data on N(p-n-pentyloxy benzylidene)p-n-alkyl anilines, 50.m series of compounds. The experimental data elucidate the interesting aspects and it is confirmed that the 50.m homologues have a unique place in nO.m compounds. The nature of the NA transition, its dependence on the nematic thermal range, the length of the alkoxy and alkyl chains are discussed. The experimental evidence suggests the presence of TCP near the 50.m homologues.