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

Research output: Contribution to journalArticle

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

Related Edinburgh Organisations

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

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.

    Research areas

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

ID: 1457958