Planar-homeotropic transition observed for B<sub>2</sub>phase of banana-shaped thioester

Ossowska-Chruściel, D.M.; Wierzejska-Adamowicz, M.; Marzec, M.; Mikułko, A.; Douali, R.; Legrand, C.; Chruściel, J.; Sikorska, A.; Wróbel, S.

doi:10.1080/01411590903461318

Cited by 5 publications

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“…For 12OSOR this process is complex: in the high temperature range of B 2 phase it is connected with reorientation of molecules around the short axis (process I), whereas in the low temperature range -around the long axis (process II) [10]. Activation energy of the process connected with fluctuations of domains is equal to ∆E = 62 kJ/mol with bias voltage (Fig.…”

Section: Dielectric Measurementsmentioning

confidence: 99%

Dielectric and Electrooptic Investigations of B Phases οf Banana-Shaped Thioesters

Wierzejska-Adamowicz

Ossowska-Chruściel²,

Chruściel³

et al. 2010

Acta Phys. Pol. A

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Electrooptic and dielectric measurements were done for B phases of two banana-shaped homologues 1,3-phenylene bis{4- [(4-nonyloxybenzoyl)sulfanyl]benzoate (9OSOR) and 1,3-phenylene bis{4-[(4-dodecyloxybenzoyl)sulfanyl]benzoate (12OSOR). Polarizing microscopy allowed to identify B 1 phase for 9OSOR and B 2 phase for 12OSOR on the basis of texture observation. Spontaneous polarization measurements were performed using reversal current method. The current response to applied triangular voltage shows that B 1 phase is a ferroelectric and B 2 phase -antiferroelectric one for which two well separated peaks were observed. Polarization for phase B 1 of 9OSOR is rather small and its temperature dependence is unusual for ferroelectric liquid crystals -it increases with temperature. Spontaneous polarization for B 2 phase of 12OSOR compound is of about 600 nC/cm 2 . Dielectric spectra measured with bias field for B 2 phase of 12OSOR show two well separated relaxation processes. In the low frequency range the relaxation process is connected with fluctuations of ferroelectric domains. The relaxation process in the high frequency range appearing also without bias field is connected with molecular reorientation. The dielectric spectra measured for B 1 phase of 9OSOR with and without bias voltage showed only one dielectric relaxation process connected with molecular reorientation around the short axis.

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Section: Dielectric Measurementsmentioning

confidence: 99%