We study phase behavior across the SmA-SmC phase transition of CE8 liquid crystal (LC) perturbed by an aerosil network. The temperature dependence of smectic ordering is measured using X-ray scattering. We reproduce qualitatively the obtained results by employing the Landau-Ginzburg-de Gennes type phenomenological approach. The experiment reveals that with increased relative concentration x of aerosil particles the smectic layers become progressively compressed. In addition a qualitative change in temperature behavior of the smectic tilt angle is observed. We explain the compression of layers as a Correspondence/Reprint request: Dr. George Cordoyiannis, National Centre for Scientific Research “Demokritos”, 153 10 Aghia Paraskevi, Greece. E-mail: gcordo@rrp.demokritos.gr George Cordoyiannis et al. 116 consequence of attraction among aerosil particles, mediated by the intervening liquid crystal phase. This gives rise to distribution of phase transition temperatures. The compression could be also caused by decreased volume available to the LC phase. We show that for x > 0.1 the experimental results could be explained only if a finite pretilt exists in the SmA phase. 6.

George Nounesis

Papers

6 Randomness in disordered aerosil liquid crystal dispersions