Electric-field-induced transition between the polarization-modulated and ferroelectric smectic- C(S) P(F)* liquid crystalline states studied using microbeam x-ray diffraction.

We report x-ray microbeam studies of a bent-core liquid crystalline material with chiral citronellyl tails. This material has an equilibrium polarization-modulated smectic-$CP$ $(\mathrm{PM}\text{\ensuremath{-}}\mathrm{Sm}CP)$ state exhibiting the ${B}_{7}$ texture upon slow cooing from the isotropic while a metastable chiral synclinic ferroelectric $\mathrm{Sm}\text{\ensuremath{-}}CP$ state $(\mathrm{Sm}\text{\ensuremath{-}}{C}_{S}{P}_{F}^{*})$ is obtained on quenching from the isotropic. The polarization modulated phase $\mathrm{PM}\text{\ensuremath{-}}\mathrm{Sm}{C}_{S}{P}_{F}^{*}$ shows typical x-ray patterns having multiple satellite peaks around the first-order layer reflection, indicating undulated layers, while the metastable $\mathrm{Sm}\text{\ensuremath{-}}{C}_{S}{P}_{F}^{*}$ state exhibits a single layering peak indicating flat layers. The $\mathrm{Sm}\text{\ensuremath{-}}{C}_{S}{P}_{F}^{*}$ state is also induced by the application of an electric field larger than the threshold field (${E}_{\text{th}}$) and thermally returns to the polarization modulated $\mathrm{PM}\text{\ensuremath{-}}\mathrm{Sm}{C}_{S}{P}_{F}^{*}$ structure.