Experimental studies in the vicinity of the C*-I* transition

Abstract

Precise layer spacing, polarisation and dielectric measurements have been performed on two compounds CE8 and 8OSI* both of which exhibit the C* and I* phases. High resolution X-ray studies confirm that the C* -I* transition is first-order in CE8, whereas the I* phase evolves continuously from the C* phase in 8OSI*. The thermal variation of the tilt order is reflected in the temperature dependence of polarisation and dielectric constants.