Critical behavior at the smectic-A to nematic transition confined to a random network.

High-resolution calorimetric study of the nematic to smectic-A transition in aligned liquid crystal-aerosil gels.

High-resolution ac calorimetry has been used to study the nematic to smectic- A (N-SmA) phase transition in the liquid crystal octylcyanobiphenyl (8CB) confined in aligned colloidal aerosil gels. A stable and robust nematic alignment was achieved by repeated thermal cycling of the samples in the presence of a strong uniform magnetic field. In some ways (such as transition temperature and integr...

Random-field effects on the nematic–smectic-A phase transition due to silica aerosil particles

A high-resolution calorimetric study has been made on the smectic-A to nematic phase transition in liquid crystals perturbed by the dispersion of 70-Å-diam silica spheres ~aerosils!. The specific heat peak of this transition decreases in amplitude and shifts to lower temperatures with increasing silica density. However, it remains sharp in comparison to the effects of aerogel confinement at the...

Calorimetric study of the nematic to smectic-A and smectic-A to smectic-C phase transitions in liquid-crystal-aerosil dispersions.

A high-resolution calorimetric study has been carried out on nanocolloidal dispersions of aerosils in the liquid crystal 4-n-pentylphenylthiol-4'-n-octyloxybenzoate (8S5) as a function of aerosil concentration and temperature spanning the smectic-C to nematic phases. Over this temperature range, this liquid crystal possesses two continuous XY phase transitions: a fluctuation-dominated nematic t...

Critical behavior at the nematic-to-smectic-A transition in a strong magnetic field.

The critical divergence of the smectic-order correlation lengths parallel and perpendicular to the director, xi( parallel, perpendicular), and the susceptibility, sigma(0), near the nematic-to-smectic-A phase transition has been measured in a 5 T magnetic field. The high magnetic field reduced the mosaicity and improved the effective transverse resolution by almost 2 orders of magnitude and per...

Critical behavior at the nematic-to-smectic-A transition in a nonpolar liquid crystal with wide nematic range.