| Autor: |
Lagerwall, Jan P. F., Parghi, Deven D., Krüerke, Daniel, Gouda, Fathi, Jägemalm, Pontus |
| Předmět: |
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| Zdroj: |
Liquid Crystals; Feb2002, Vol. 29 Issue 2, p163-178, 16p, 4 Black and White Photographs, 4 Diagrams, 1 Chart, 8 Graphs |
| Abstrakt: |
Using a variety of optical and electro-optical techniques, as well as dielectric spectroscopy, we have investigated three homologues in the chiral liquid crystal series nF1M7, where n denotes the length of the unbranched terminal chain. The main focus of the study is the series of smectic C subphases, i.e. SmC*[sub α] , SmC*[sub 1/3] and SmC*[sub 1/4]. During switching in the SmC*[sub α] phase, a peculiar redirection of the plane of biaxiality, distinguishing this phase from SmA* and SmC*, was observed. We present a simple explanation for this behaviour which correlates well with the clock model description of the SmC*[sub α] phase. We found a zero mesoscopic polarization for the SmC*[sub 1/4] phase and a non-zero mesoscopic polarization for SmC*[sub 1/3], observations which are consistent with a distorted clock model. The dielectric spectroscopy investigations, performed at several different cell gaps, clearly show that the dielectric response in these materials is easily dominated by surface-induced structures if the cell gap is reduced, thus reflecting that the bulk thermodynamic phase exists in very thick cells only. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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