Simultaneous dielectric and A.C. electrooptic measurements near the phase transition of tanane

Abstract
The complex electrooptic coefficient f 63 (v, T) has been measured over a large frequency range (0.0003 HzTc ). A critical dispersion has been observed at very low frequency, and is attributed to static defects or mechanical imperfections. In the vicinity of Tc . simultaneous measurements of the dielectric constant ε33 (1500 Hz) and the electrooptic coefficient. f 63 (1500 Hz) show that they are linearly coupled by a temperature independent coefficient which is not affected by the dispersion.