Optical microscopy, DSC and dielectric relaxation spectroscopy studies on a partially fluorinated ferroelectric liquid crystalline compound MHPO(13F)BC

Phase transitions in a partially fluorinated compound, MHPO(13F)BC, have been studied by optical microscopy, calorimetry and miscibility methods. Spontaneous polarization (P S ), helical pitch measurements, and frequency-domain dielectric study, have also been carried out. These studies indicate the...

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Bibliographic Details
Published in:Phase transitions 2006-03, Vol.79 (3), p.223-235
Main Authors: Mandal, P. K., Jaishi¶, B. R., Haase, W., Dabrowski, R., Tykarska, M., Kula, P.
Format: Article
Language:English
Subjects:
Dielectric spectroscopy
Goldstone modes
Helical pitch
Miscibility
SmC
Soft modes
Spontaneous polarization
subphase
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Summary:Phase transitions in a partially fluorinated compound, MHPO(13F)BC, have been studied by optical microscopy, calorimetry and miscibility methods. Spontaneous polarization (P S ), helical pitch measurements, and frequency-domain dielectric study, have also been carried out. These studies indicate the presence of an intermediate alpha sub-phase between a ferroelectric and a paraelectric phase. Both the Goldstone-mode (GM) and the soft-mode (SM) relaxation processes have been observed, and by fitting the spectra to the Cole-Cole function, values of dielectric strengths, critical frequencies and dispersion parameters have been determined. Anomalies have been observed in the temperature dependence of P S and inverse dielectric strength, which are interpreted as a signature of a phase between the SmC* and SmA* phases. Microscopic patterns, helical pitch measurements, and miscibility studies give further evidence in support of this inference.
ISSN:0141-1594
1029-0338
DOI:10.1080/01411590500500724