J. Phys. IV France
Volume 125, June 2005
Page(s) 245 - 247

J. Phys. IV France 125 (2005) 245-247

DOI: 10.1051/jp4:2005125058

Investigation of the critical behavior at lyotropic systems by collinear mirage technique

B.S.L. Honda1, H. Mukai2, P.R.G. Fernandes2 and S.M. Shibli1

1  Instituto de Física, Universidade de São Paulo, Caixa Postal 66318, 05315-970, São Paulo, Brazil
2  Departamento de Física, Universidade Estadual de Maringá, Av. Colombo, 5790, 87020-900, Maringá, Paraná, Brazil

We investigate the behavior of the thermal diffusivity (D) in the vicinity of the nematic to isotropic (N - I) and uniaxial to biaxial (N - N) phase transitions for different lyotropic liquid crystals. For the first time, collinear mirage effect technique is used to observe that the presence of a peak in the thermal diffusivity is accomplished by a phase transition due to the variation at the sample's temperature. Furthermore, we show that our experimental setup is sensitive to both first and second order transitions in lyotropic systems. We also propose a critical exponent related to the thermal diffusivity.

© EDP Sciences 2005