Temperature-Dependent Tilt Angle in the Smectic<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>C</mml:mi></mml:math>Phase of a Liquid Crystal

Abstract

Measurement of the tilt angle of the smectic $C$ phase of terephthal-bis-($4\ensuremath{-}n\ensuremath{-}\mathrm{b}\mathrm{u}\mathrm{t}\mathrm{y}\mathrm{l}\mathrm{a}\mathrm{n}\mathrm{i}\mathrm{l}\mathrm{i}\mathrm{n}\mathrm{e}$) has been made using conoscopic observation and circularly polarized light. The new phenomenon of a smectic $C$ phase with a temperature-dependent tilt angle is reported. Terephthal-bis-($4\ensuremath{-}n\ensuremath{-}\mathrm{b}\mathrm{u}\mathrm{t}\mathrm{y}\mathrm{l}\mathrm{a}\mathrm{n}\mathrm{a}\mathrm{l}\mathrm{i}\mathrm{n}\mathrm{e}$) has nematic, smectic $A$, smectic $C$, and smectic $B$ liquid-crystalline phases. The tilt angle of smectic $C$ changes from 0\ifmmode^\circ\else\textdegree\fi{} at the smectic-$A\ensuremath{-}\mathrm{s}\mathrm{m}\mathrm{e}\mathrm{c}\mathrm{t}\mathrm{i}\mathrm{c}\ensuremath{-}C$ transition to approximately 26\ifmmode^\circ\else\textdegree\fi{} at the $\mathrm{s}\mathrm{m}\mathrm{e}\mathrm{c}\mathrm{t}\mathrm{i}\mathrm{c}\ensuremath{-}C\ensuremath{-}\mathrm{s}\mathrm{m}\mathrm{e}\mathrm{c}\mathrm{t}\mathrm{i}\mathrm{c}\ensuremath{-}B$ transition temperature.