Density studies across smectic‐smectic transitions in 70.6 and 80.10

Abstract

Abstract The temperature dependence of density in N(p‐n‐heptyloxy benzylidene) p‐n‐hexylaniline (70.6) and in N(p‐n‐octyloxy benezylidene) p‐n‐decylaniline (80.10) is carried out to study the nature of the phase transitions associated density jumps, to estimate the pressure dependence of transition temperatures and pretransitional effects. The compounds 70.6 exhibits a phase variant ACFG whereas 80.10 exhibits a new phase sequence variant ABF. The isotropic‐smectic A, semctic A‐smectic B and semctic C‐smectic F phase transitions are found to be first order. The calculated thermal expansion coefficient also supported the density results. The density jumps, associated enthalpies and estimated pressure dependence of transition temperatures at the isotropic‐smectic A phase transformation in other compounds are presented.