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Binary separation in very thin nematic films: thickness and phase coexistence

D. van Effenterre·R. Ober·M. P. Valignat·A. M. Cazabat
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Abstract

The behavior as a function of temperature of very thin films (10 to 200 nm) of pentylcyanobiphenyl (5CB) on silicon substrates is reported. In the vicinity of the nematic/isotropic transition we observe a coexistence of two regions of different thicknesses: thick regions are in the nematic state while thin ones are in the isotropic state. Moreover, the transition temperature is shifted downward following a 1/h^2 law (h is the film thickness). Microscope observations and small angle X-ray scattering allowed us to draw a phase diagram which is explained in terms of a binary first order phase transition where thickness plays the role of an order parameter.

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D. van Effenterre, R. Ober, M. P. Valignat, A. M. Cazabat. 2001-06-06. Binary separation in very thin nematic films: thickness and phase coexistence. https://doi.org/10.1103/physrevlett.87.125701

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