Anomalous temperature dependence of layer spacing of de Vries liquid crystals: Compensation model

K. Merkel, A. Kocot, J. K. Vij, P. J. Stevenson, A. Panov, D. Rodriguez

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Abstract

Smectic liquid crystals that exhibit temperature independent layer thickness offer technological advantages for their use in displays and photonic devices. The dependence of the layer spacing in SmA and SmC phases of de Vries liquid crystals is found to exhibit distinct features. On entering the SmC phase, the layer thickness initially decreases below SmA to SmC (TA-C) transition temperature but increases anomalously with reducing temperature despite the molecular tilt increasing. This anomalous observation is being explained quantitatively. Results of IR spectroscopy show that layer shrinkage is caused by tilt of the mesogen's rigid core, whereas the expansion is caused by the chains getting more ordered with reducing temperature. This mutual compensation arising from molecular fragments contributing to the layer thickness differs from the previous models. The orientational order parameter of the rigid core of the mesogen provides direct evidence for de Vries cone model in the SmA phase for the two compounds investigated.

Original languageEnglish
Article number243301
JournalApplied Physics Letters
Volume108
Issue number24
DOIs
Publication statusPublished - 13 Jun 2016

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liquid crystals
spacing
temperature dependence
shrinkage
temperature
cones
transition temperature
fragments
photonics
expansion
spectroscopy

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Merkel, K. ; Kocot, A. ; Vij, J. K. ; Stevenson, P. J. ; Panov, A. ; Rodriguez, D. / Anomalous temperature dependence of layer spacing of de Vries liquid crystals: Compensation model. In: Applied Physics Letters. 2016 ; Vol. 108, No. 24.
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Anomalous temperature dependence of layer spacing of de Vries liquid crystals: Compensation model. / Merkel, K.; Kocot, A.; Vij, J. K.; Stevenson, P. J.; Panov, A.; Rodriguez, D.

In: Applied Physics Letters, Vol. 108, No. 24, 243301, 13.06.2016.

Research output: Contribution to journalArticle

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AU - Merkel, K.

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AU - Rodriguez, D.

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