Regensburg 2013 – scientific programme
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DF: Fachverband Dielektrische Festkörper
DF 9: Glasses and Glass Transition I (joint session with CPP, DY)
DF 9.4: Talk
Monday, March 11, 2013, 16:00–16:15, H34
Molecular dynamics of a discotic liquid crystal studied by Dielectric Relaxation and Specific Heat Spectroscopy — •Christina Krause1, Huajie Yin1, Andreas Wurm2, Christoph Schick2, and Andreas Schönhals1 — 1BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, D-12205 Berlin — 2Institute of Physics, University of Rostock, Wismarsche Straße 43-45, D-18051 Rostock
The molecular dynamics of the discotic liquid crystal pyrene-1,3,6,8-tetracarboxylic tetra(2-ethylhexyl)ester is investigated by dielectric relaxation and specific heat spectroscopy. The data from dielectric spectroscopy shows 3 processes: a β-relaxation at low temperatures and an α-relaxation in the temperature range of the mesophases followed by conductivity. In both phases the dielectric α-relaxation is assigned to restricted glassy dynamics. Glassy dynamics is also detected in the plastic crystalline phase by means of specific heat spectroscopy but with a different temperature dependence of the relaxation rates. This is discussed considering the different molecular restrictions of the fluctuations: close to the columns (dielectric spectroscopy) and more in the intercolumnar space (specific heat spectroscopy). In the frame of the fluctuation approach a correlation length of glassy dynamics is calculated to 0.78 nm which correlates well to the core-core distance estimated by X-ray scattering.