Dielectric and phase behaviors of blue-phase liquid crystals

Dielectric spectra of two pristine blue-phase liquid crystals and a polymer-stabilized counterpart were acquired at various temperatures in conjunction with simultaneous observations of their optical transmission spectra and birefringent textures. The temperature-dependent dielectric data at 5.5 kHz were specifically retrieved for further examination of the feasibility of the dielectric technique as a means to identify phase transitions. With complementary identification by optical images at specific temperatures, it is suggested that investigations of the second derivative of the real-part permittivity with respect to the temperature can be considered as one of the applicable ways to depict the phase sequence of the blue-phase liquid crystals on the cooling process from the isotropic phase through the chiral nematic phase.