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Article Dans Une Revue Physical Review E : Statistical, Nonlinear, and Soft Matter Physics Année : 2006

Optical and confocal microscopy observations of screw dislocations in smectic-A liquid crystals

Résumé

We present experimental evidence of the presence of isolated screw dislocations in smectic-A liquid crystals observed by polarizing microscopy. In a wedge-shaped homeotropic cell, the edge and screw dislocations interaction gives rise to a strong-enough optical contrast and makes visible their mutual intersections at temperatures close to the smectic-A to smectic-C phase transition temperature. The nature of the defects is confirmed by confocal microscopy observations. At large scale we observe a forest of screw dislocations, perpendicular to the smectic layers, across the thickness of the cell (end-on configuration). Their density varies between 109 and 1012m−2. In situ observations of dislocations under stress, in the optical microscope, provide quantitative information about the screw-edge dislocation interactions. The latter interaction is calculated in the unharmonic approximation and it gives rise to an observed yield stress.
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hal-01208105 , version 1 (01-10-2015)

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Ioannis Lelidis, Christophe Blanc, M. Kléman. Optical and confocal microscopy observations of screw dislocations in smectic-A liquid crystals. Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, 2006, 74 (5), pp.051710. ⟨10.1103/PhysRevE.74.051710⟩. ⟨hal-01208105⟩
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