Structure and Properties of the Cholesteric Blue Phases

Abstract

A study of Bragg reflections in both blue phases (BPI, BPII) of two mixtures of chiral and nonchiral biphenyls indicates both phases probably have the same translational symmetry and are either body-centered or simple cubic. The temperature dependence of several Bragg reflections indicates that the BPI-BPII transition may be either continuous or discontinuous and that, given the bcc lattice, the lattice parameter is commensurate with the pitch. These results are discussed relative to existing theories.