High resolution x-ray study of nematic-smectic-A and Smectic-A-reentrant nematic transitions in liquid crystal+aerosil gels
arXiv:0711.2763 · doi:10.1103/PhysRevE.77.031702
Abstract
We have studied the effects of quenched random disorder created by dispersed aerosil nanoparticle gels on the nematic to smectic-A (N-SmA) and smectic-A to reentrant nematic (SmA- RN) phase transitions of thermotropic liquid crystal mixtures of 6OCB (hexyloxycyanobiphenyl) and 8OCB (octyloxycyanobiphenyl). These effects are probed using high-resolution synchrotron x-ray diffraction techniques. We find that the reentrant characteristics of the system are largely unchanged by the presence of the aerosil gel network. By comparing measurements of the smectic static structure amplitude for this 8OCB-6OCB+aerosil system with those for butyloxybenzilidene-octylaniline (4O.8)+aerosil gels, we find that the short-range smectic order in the smectic-A phase is significantly weaker in the reentrant system. This result is consistent with the behavior seen in pure 8OCB-6OCB mixtures. The strength of the smectic ordering decreases progressively as the 6OCB concentration is increased. Detailed line shape analysis shows that the high- and low-temperature nematic phases (N and RN) are similar to each other.
34 Pages, 11 Figures, A regular Article submitted to PRE
References in corpus (7)
- Smectic ordering in liquid crystal - aerosil dispersions I. X-ray scattering
- First evidence of anisotropic quenched disorder effects on a smectic liquid crystal confined in porous silicon
- Smectic ordering in liquid crystal - aerosil dispersions II. Scaling analysis
- Evolution of the isotropic to nematic phase transition in octyloxycyanobiphenyl+aerosil dispersions
- Smectic Liquid Crystals in an Anisotropic Random Environment
- High-resolution x-ray study of the nematic - smectic-A and smectic-A - smectic-C transitions in 8barS5-aerosil gels
- First order isotropic - smectic-A transition in liquid crystal-aerosil gels