Hydrogen-bonded Silica Gels Dispersed in a Smectic Liquid Crystal: A Random Field XY System

摘要

The effect on the nematic to smectic-A transition in octylcyanobiphenyl (8CB)due to dispersions of hydrogen-bonded silica (aerosil) particles ischaracterized with high-resolution x-ray scattering. The particles form weakgels in 8CB creating a quenched disorder that replaces the transition with thegrowth of short range smectic correlations. The correlations include thermalcritical fluctuations that dominate at high temperatures and a secondcontribution that quantitatively matches the static fluctuations of a randomfield system and becomes important at low temperatures.