Identification of a TGBA liquid crystal phase via its defects |
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| Authors: | YuA Nastishin M Kléman J Malthête HT Nguyen |
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| Institution: | (1) Laboratoire de Minéralogie-Cristallographie de Paris (UMR7590), T16 case 115, 4 place Jussieu, F-75252 Paris cédex 05, France, FR;(2) Institute for Physical Optics, 23 Dragomanov str., Lviv 290005 Ukraine, UA;(3) Institut Curie, Section de recherche, CNRS UMR 168, 11 rue Pierre et Marie Curie, Paris cédex, 05 France, FR;(4) Centre de recherche Paul Pascal, CNRS UPR 8641, avenue Albert Schweitzer, 33600 Pessac cédex, France, FR |
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| Abstract: | We have shown that cholesteryl nonanoate, a thermotropic compound which is well known to exhibit pretransitional effects at
the smectic A (SmA) cholesteric (N*) transition (W.L. McMillan, Phys. Rev. A 4, 1238 (1971); 6, 936 (1972)), has in fact a TGBA phase in between. Our arguments rely on the observation of new TGBA defects, either in Robinson
spherulites cooled from the N* phase or in free-standing films. The same new defects can be obtained in a well-documented
TGBA phase of a tolane compound. We analyze qualitatively the TGBA defects in both geometries, in particular their relation
to the disclination radius of the N* Robinson spherulites.
Received 12 February 2001 |
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| Keywords: | PACS 61 30 Jf Defects in liquid crystals – 61 72 -y Defects and impurities in crystals microstructure – 64 70 Md Transitions in liquid crystals |
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