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Volumn 25, Issue 3, 2008, Pages 277-289

Lehmann effect in a compensated cholesteric liquid crystal: Experimental evidence with fixed and gliding boundary conditions

Author keywords

[No Author keywords available]

Indexed keywords

LEHMANN EFFECT; PLANAR GLIDING ANCHORING; THERMOMECHANICAL COUPLING;

EID: 42149120072     PISSN: 12928941     EISSN: 1292895X     Source Type: Journal    
DOI: 10.1140/epje/i2007-10290-4     Document Type: Article
Times cited : (25)

References (27)
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    • note
    • As pointed out by Pawel Pieranski, convection must develop in the sample as long as it is submitted to a horizontal temperature gradient. As a result, the director field must distort in homeotropic samples because of the shear flow. It can be checked that this effect should lead to a phase shift Φ ab{H}} proportional to 9. This dependence is very different from that observed experimentally (Φ{\ab{H}}\propto d 5), suggesting that hydrodynamic effects are negligible in our experiments. This conclusion agrees with the experimental results of Éber and Jánossy eber1 who found that Φ{\ab{H}}= 0 at all temperature gradients in a pure nematic (8CB).
  • 17
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    • note
    • We emphasize that in the planar geometry the convection does not destabilize the director field as the director is perpendicular to the shear plane.
  • 18
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    • note
    • Note that we have implicitly assumed that ν{eff} is positive as in the mixture 8CB+CC, for which this result was proved experimentally by Éber and Jánossy in reference eber2. We emphasize that taking ν{eff}<0 would have lead to ν=-10.4\times10{-7}kg K-1 s-2, which is more than three times larger in absolute value than the retained value. The conclusion is that, in all cases, ν is different from 0, which is the main result of this article.
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* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.