title: Critical anomalies in thermal diffusivity of liquid-crystalline terephthal-bis-(4-n-butylaniline).
abstract: A temperature wave method has been applied to observe the thermal diffusivity through the isotropic (Iso)-nematic (N)-smectic Sm-A-Sm-C-Sm-B-crystals VI-VII-VIII phase transitions of terephthal-bis-(4-n-butylaniline) (TBBA). Critical anomalies have been found in the N-Sm-A and Sm-C-Sm-B phase transitions as diplike shaped, consistent with the predictions based on the dissipative couplings between the order parameter and the conserved free-energy density. Singular points with a gap have been observed at the Sm-B-crystal VI, crystals VI-VII, and crystals VII-VIII phase transitions, which show polymorphic behaviors on heating and cooling. The second-order Sm-A-Sm-C phase transition emerged as a singular temperature dependence. In all the phases thermal diffusivity decreases with increasing temperature except for Sm-C, where thermal diffusivity increases with increasing temperature. The origin of the anomaly in the thermal diffusivity in Sm-C is discussed based on the parametric analysis of dynamic critical behavior in the Sm-A-Sm-C phase transitions together with the tilt angle change obtained by use of simultaneous measurements of x-ray diffraction and differential scanning calorimetry.
authors.affiliation: Tokyo Institute of Technology, O-okayama 2-12-1, Tokyo 152-8550, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Morikawa
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Hashimoto
authors.forename: Akira
authors.initials: A
authors.lastname: Kishi
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Shinoda
authors.forename: Kenji
authors.initials: K
authors.lastname: Ema
authors.forename: Hideo
authors.initials: H
authors.lastname: Takezoe
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D003198:Computer Simulation; D003460:Crystallization / Q000379:methods*; D004058:Diffusion; D050866:Liquid Crystals; D008956:Models, Chemical; D008958:Models, Molecular; D044367:Phase Transition; D013696:Temperature; D013814:Thermal Conductivity
chemical_list: D000814:Aniline Compounds; C487962:terephthalidine-bis-butylaniline