کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5411973 | 1506588 | 2013 | 7 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Molecular and dynamical properties of a perfluorinated liquid crystal with direct transition from ferroelectric SmCâ phase to isotropic phase
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
One recently synthesized partially fluorinated ferroelectric liquid crystal is investigated by X-ray diffraction, dielectric relaxation spectroscopy and electrooptic techniques. It exhibits only ferroelectric SmCâ phase over a broad temperature range and it directly goes to isotropic phase from SmCâ phase which is rare in ferroelectric liquid crystals. Tilt angle, measured by X-ray and optical methods, is found to be high. Only Goldstone mode relaxation process is observed. Increase of dielectric strength and critical frequency with temperature has been explained in the light of generalized Landau model. No soft mode is observed since the compound directly melts into isotropic phase. It possesses moderate value of spontaneous polarization and the data fitted nicely to mean-field model and reproduced critical temperature within 0.5°. Fitted critical exponent (0.29) suggests that SmC*-I transition is first order which is supported by DSC measurements. Goldstone mode rotational viscosity is found to obey Arrhenius behavior, thermal activation energy was found to be 97.1 kJ molâ 1. Very fast switching is observed under square pulse. The compound induces ferroelectric phase even below room temperature when mixed in a proper host mixture.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Liquids - Volume 182, June 2013, Pages 95-101
Journal: Journal of Molecular Liquids - Volume 182, June 2013, Pages 95-101
نویسندگان
D. Goswami, D. Sinha, A. Debnath, P.K. Mandal, S.K. Gupta, W. Haase, D. Ziobro, R. Dabrowski,