Calorimetric investigations of liquid-crystal compounds exhibiting almost no layer-shrinkage behavior through the smectic‐Asmectic‐C* transition

K. Ema, K. Takekoshi, H. Yao, S. T. Wang, and C. C. Huang
Phys. Rev. E 71, 031706 – Published 25 March 2005

Abstract

Heat-capacity measurements have been made on liquid-crystal compounds exhibiting almost no layer-shrinkage (NLS) behavior through the SmASmC* phase transition. The transition was found to be second order for two of the substances studied. It was found that the heat-capacity anomaly accompanying a second-order SmASmC* transition with NLS behavior is quite similar to that observed for typical antiferroelectric liquid crystals of the 4-(1-methylheptyloxycarbonyl)phenyl 4-octyloxybiphenyl-4-carboxylate (MHPOBC) group, showing three-dimensional (3D) XY behavior in the vicinity of the transition. On the other hand, for one compound which shows a weakly first-order transition, the anomaly is almost symmetric above and below Tc, with a significant fluctuation effect in the SmA phase. For this compound, the critical behavior of the heat-capacity anomaly is almost tricritical in the immediate vicinity of Tc, while away from Tc the behavior can be explained with the 3D XY model. This suggests that the underlying transition with the 3D XY critical behavior is driven to almost being tricritical but remaining weakly first order. No indication of low-dimensional character in the critical behavior was found in both cases.

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  • Received 1 November 2004

DOI:https://doi.org/10.1103/PhysRevE.71.031706

©2005 American Physical Society

Authors & Affiliations

K. Ema*, K. Takekoshi, and H. Yao

  • Department of Physics, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 Oh-okayama, Meguro, Tokyo, 152-8550, Japan

S. T. Wang and C. C. Huang

  • School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA

  • *Corresponding author. Email address: kema@phys.titech.ac.jp

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Vol. 71, Iss. 3 — March 2005

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