Experimental evidence for a hexagonal Blue Phase

Experimental evidence for a Blue Phase of hexagonal symmetry is reported. In agreement with a theoretical prediction by Hornreich et al., this new Blue Phase has been found in a short pitch cholesteric liquid crystal of positive dielectric anisotropy submitted to a large enough electric field. Its symmetry, compatible with crystal forms and with Bragg reflections, is either P6 1 22 or P6 2 22. The phase is three-dimensional in contradistinction with theoretically considered two-dimensional models En accord avec les predictions theoriques de Hornreich et al. cette nouvelle phase apparait dans des cristaux liquides cholesteriques de petit pas, d'anisotropie dielectrique positive et soumis au champ electrique d'intensite suffisante