Transitions de Phase en Series Mesogenes: |
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| Authors: | N B Chanh M Cotrait J Gautlier Y Haget Nguyen Huu Tinh C Polycarpeet |
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| Institution: | 1. Laboratoire de Cristallographie et de Physique Cristalline , associé au C.N.R.S. LA. 144-351, Cours de la Libération , 33405, Talence, Cedex, France;2. Centre de Recherche Paul Pascal , Domaine Universitaire , 33405, Talence, Cedex, France |
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| Abstract: | The polymorphism of the di(4-alkylphenyl) and di(4-alkoxyphenyl) tetrathiafulvalene (TTF) is investigated by optical, crystallographic and calorimetric methods. All the studied derivatives are mesomorphic. The first mesophase is always a smectic G phase; the second one is a nematic N phase for short chains and a smectic C phase for long chains. The entropies corresponding to the passage high-temperature crystalline phase C1 → SG and to the “melting” (C1 → mesophases → isotropic phase I) increase with the length of the chain and with the presence of the oxygen atom in the radical. |
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