title: Measurements of the dielectric and viscoelastic constants in mixtures of 4,4'-n-octyl-cyanobiphenyl and biphenyl.
abstract: We performed measurements of the dielectric constants, splay elastic constant, and rotational viscosity of the nematic phase of mixtures of 4,4'-n-octyl-cyanobiphenyl (8CB) and biphenyl (BP). In contrast with previous results of DasGupta et al. [Phys. Rev. E 63, 041703 (2001); Phys. Lett. A 288, 323 (2001)], we do not find any anomaly of these constants when the smectic-A phase is approached at all concentrations of BP. These results are compatible with recent calorimetric measurements of Denolf et al. [Phys. Rev. Lett. 97, 107801 (2006); Phys. Rev. E 76, 051702 (2007)] and the absence of a tricritical point in the phase diagram. The origin of the anomalies observed by DasGupta et al. at large concentration of BP is also briefly discussed and a likely explanation in terms of biphenyl evaporation is proposed.
authors.affiliation: Université de Lyon, Ecole Normale Supérieure de Lyon, Laboratoire de physique, 46 Allé d'Italie, 69364 Lyon, Cedex 07, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Oswald
authors.affiliation: Université de Lyon, Ecole Normale Supérieure de Lyon, Laboratoire de physique, 46 Allé d'Italie, 69364 Lyon, Cedex 07, France.
authors.forename: Camille
authors.initials: C
authors.lastname: Scalliet