J. Phys. III France
Volume 2, Number 6, June 1992
Page(s) 1029 - 1038
DOI: 10.1051/jp3:1992176
J. Phys. III France 2 (1992) 1029-1038

Piezothermal analysis of the N $_{\rm Re}$-S $_{\rm Ad}$ transition on small samples of p-octylbenzoate p-cyanobenzoyloxyphenyl

A. Anakkar1, J. M. Buisine1, C. Alba-Simionesco2, L. Ter Minassian2, H. T. Nguyen3 and C. Destrade3

1  Equipe de Dynamique et Structure des Matériaux Moléculaires, U.A. CNRS n° 801, Université des Sciences et Technologies de Lille, 59655 Villeneuve d'Ascq, France
2  Laboratoire de Chimie Physique, Université Pierre et Marie Curie, U.A. CNRS n° 176, U.A. CNRS n° 721, 11 rue P. et M. Curie, 75231 Paris Cedex, France
3  Centre de Recherche Paul Pascal, Domaine Universitaire, 33405 Talence Cedex, France

(Received 16 December 1991, accepted 27 February 1992)

In order to detect weakly first-order phase transitions by means of piezothermal measurements on small samples of calamitic mesogens exhibiting reentrant phenomena, a new high pressure calorimeter equipped with a composite slab thermostat has been built. Its efficiency has been proved and its performances determined. Its use on a ten cubic millimeter effective volume of p-octylbenzoate p-cyanobenzoyloxyphenyl has permitted to prove the N $_{\rm Re}$-S $_{\rm Ad}$ transition is not purely second order but weakly first-order.

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