Liquid crystal materials that exhibit apparently a single ferrielectric phase in a wide temperature range are reported to show the V-shaped switching. To clarify the phase structure, we have studied one of such LC compounds and found that the helicoidal pich changes continuously in a wide temperature range (more than 100℃), that the dielectric constant is as large as that of ferroelectric phase, and that the melatopes of the conoscopic figure scarcely split by applying an electric field. These results indicate almost continuous emergency of a variety of commensurate and/or incommensurate phase structures near the sprl region in the ANNNI model proposed by Yamashita. More details of the structure can be clarified by resonant X-ray scattering, since the constituent molecule contains a Cl atom.
