Nonlinear dielectric study of pretransitional effects in liquids above the phase transition temperature

Abstract

Variations in dielectric permittivity in an electric field (NDE) rae measured for two solutions in the single-phase precritical region and for the isotropic phase of MBBA above the clearing temperature T c. The magnitude of the effect measured in the critical solutions is proportional to ( T- T c) −ζ, where ζ ≈ 1 3 , pointing to a relationship with fluctuations in density and concentrations. In MBBA, the effect is proportional to ( T - T*) −ζ, where ζ ≈ 1 and T* = T c - 0.7°. The results and their discussion show that NDE is an efficient method for the study of phase transitions in liquids, especially pretransitional effects at temperatures even 10–20° above the transition point.