Abstract
X-ray data are reported for the nematic phase near the nematic (N)–smectic-(Sm-) transition in a binary mixture of pentylphenylcyanobenzoyloxy benzoate (CN)+cyanobenzoyloxypentylstilbene ( stilbene). These data and x-ray data from four other N–Sm- systems, plus the corresponding high-resolution data, are analyzed using the exact solutions of preasymptotic three-dimensional (3D) XY theory. The correlation volume , smectic susceptibility σ, and heat capacity are in good agreement with preasymptotic theoretical predictions. First-order corrections-to-scaling terms were known previously to be important for describing ; their importance for and σ is demonstrated here. Many universal features of the 3D XY model are confirmed by the present self-consistent analysis, but the critical anisotropy of the individual lengths and and the fact that exhibits a normal XY amplitude ratio rather than the theoretically predicted inverted ratio are still unresolved issues.
- Received 18 June 1992
DOI:https://doi.org/10.1103/PhysRevE.47.1918
©1993 American Physical Society