First-order isotropic-smectic-A transition in liquid-crystal-aerosil gels

M K Ramazanoglu, Paul Clegg, R J Birgeneau, C W Garland, M E Neubert, J M Kim

Research output: Contribution to journalArticlepeer-review

Abstract

The short-range order which remains when the isotropic to smectic- A transition is perturbed by a gel of silica nanoparticles (aerosils) has been studied using high-resolution synchrotron x-ray diffraction. The gels have been created in situ in decylcyanobiphenyl, which has a strongly first-order isotropic to smectic- A transition. The effects are determined by detailed analysis of the temperature and gel density dependence of the smectic structure factor. In previous studies of the continuous nematic to smectic- A transition in a variety of thermotropic liquid crystals the aerosil gel appeared to pin, at random, the phase of the smectic density modulation. For the isotropic to smectic- A transition the same gel perturbation yields different results. The smectic correlation length decreases more slowly with increasing random-field variance in good quantitative agreement with the effect of a random pinning field at a transition from a uniform phase directly to a phase with one-dimensional translational order. We thus compare the influence of random fields on a freezing transition with and without an intervening orientationally ordered phase.

Original languageEnglish
Article number061706
Pages (from-to)-
Number of pages8
JournalPhysical Review E - Statistical, Nonlinear and Soft Matter Physics
Volume69
Issue number6
DOIs
Publication statusPublished - Jun 2004

Keywords

  • X-RAY-SCATTERING
  • PHASE-TRANSITIONS
  • ORIENTATIONAL ORDER
  • HEAT-CAPACITY
  • RANDOM-FIELDS
  • BEHAVIOR
  • OCTYLCYANOBIPHENYL
  • DISORDER
  • SYSTEMS

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