Small Angle X-Ray Diffraction Studies of an Ester/Biphenyl Mixture (5CB/ME 50.5) Showing an Injected Smectic Phase
作者:
M.K. Das,
R. Paul,
D.A. Dunmur,
期刊:
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals
(Taylor Available online 1995)
卷期:
Volume 258,
issue 1
页码: 239-252
ISSN:1058-725X
年代: 1995
DOI:10.1080/10587259508034564
出版商: Taylor & Francis Group
关键词: injected smectic phase;order parameters;layer thickness;X-ray diffraction.
数据来源: Taylor
摘要:
The molecular organisation in a binary mixture of a strongly polar mesogen (5CB) and a weakly-polar mesogen (ME50.5) is investigated using results of X-ray scattering and density studies. Analysis of the intensity distribution of X-ray scattering has yielded results for orientational order parameters in addition to smectic layer spacings and effective molecular lengths. The results are compared with a mean field theory of the smectic phase. Previously unexplained results for mixtures showing a minimum in the anisotropy of physical properties coincident with a maximum in the nematic/smectic A transition entropy are shown to be consistent with the theory. We conclude that favourable packing of molecules in the injected smectic A phase stabilises the layers but increases the orientational free volume, consistent with a lower orientational order parameter.
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