Studies of Phase Diagram and Glass Transitions of a Liquid Crystal with Ferro- and Antiferroelectric Phases

Abstract

Based on the results of the dierential scanning calorimetry, of transmitted light intensity measurements and of texture observations the phase diagram of 4-(6-heptauorobutanoiloxyhexyloxy)biphenyl-4 -carboxylate(S)--4-(methyloheptyloxy-1-carbonyl)-phenyl (4H6) was obtained. The following phases were identied on cooling:isotropic, smectic A, smectic C * , smectic C * A phases and a highly ordered phase called SmX and its glass. During heating transformation from glass of SmX to SmX phase and then transition to a metastable Cr2 phase, evolving to the more stable Cr1 phase, were observed. On further heating SmC * A , SmC * and Sm phases were identied.When Cr2 was cooled, a glass transition was also observed.

Relaxation dynamics and crystallization study of glass-forming chiral-nematic liquid crystal S,S-2,7-bis(4-pentylphenyl)-9,9-dimethylbutyl 9H-fluorene (5P-Am*FLAm*-P5)

“…3). Cracks appeared on the texture at low temperatures, then disappeared upon heating around 273 K; this was followed by a transformation of the N * phase to the isotropic state (Is), then the Is phase immediately crystallized to Cr1 at 304 K. Previously, similar cracking behavior was found for vitrification other materials [26,[34][35][36], and we propose the following phase sequence on cooling: Is-Cr1, GCr1 (glass of Cr1). In the case of fast cooling, a small volume of the isotropic phase first forms another crystal Cr2 at 300 K; following this, the transition Is-N * and formation of the glass of N * (GN * ) occur in the presence of Cr2 ( fig.…”

Modification of AFLC Physical Properties by Doping with BaTiO3 Particles

“…In the antiferroelectric SmC* A phase, a characteristic fan-shaped texture with fingers was registered (Figure d) which slightly changes color and the fingers disappear as the temperature decreases (Figure e). The polygonal inclusions exist in the texture of the antiferroelectric SmC* A phase both for AFLC mixture and composite 2 .…”