Heat capacities and phase transitions of the antiferroelectric liquid crystals MHPOBC and MHPOCBC
作者:
S. ASAHINA,
M. SORAI,
A. FUKUDA,
H. TAKEZOE,
Y. SUZUKI,
I. KAWAMURA,
K. FURUKAWA,
K. TERASHIMA,
期刊:
Liquid Crystals
(Taylor Available online 1997)
卷期:
Volume 23,
issue 3
页码: 339-348
ISSN:0267-8292
年代: 1997
DOI:10.1080/026782997208262
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
Heat capacities of the antiferroelectric liquid crystals 4-(1-methylheptyloxycarbonyl)phenyl4-octyloxybiphenyl-4-carboxylate (MHPOBC) and 4-(1-methylheptyloxycarbonyl)phenyl4-octylcarboxybiphenyl-4-carboxylate (MHPOCBC), have been measured with an adiabatic calorimeter between 350 and 460 K. MHPOBC showed three smectic subphases (ferrielectric C*, ferroelectric C* and a fancy phase C*) between antiferroelectric smectic C* and paraelectric gamma alpha smectic A, while MHPOCBC exhibited only one subphase (smectic C*). These phases are clearly discriminated by the existence of phase transitions. The enthalpies and entropies gained at the respective phase transitions were very small. A much larger phase transition from smectic A to isotropic liquid was also observed in both compounds. A alpha
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