Phase Diagram of Blue Phases

Blue phases exist in a narrow temperamre region between the isotropic and cholesteric phases. As temperamre is decreased, the order of appearance of the blue phases is BPIII, BPII, and BPI [15-17]. Whether a chiral liquid crystal has a blue phase depends on its molecular stmcmre and chirality. The blue phases can be identified by an optical microscope under reflection mode. BPI and BPII have bright and colorful multi-domain crystal plate textures, while BPIII has a dim uniform foggy texmre [5,18]. Therefore, BPIII is also called the fog phase. As will be discussed later, BPI and BPII have cubic crystal structures while BPIII has an amorphous stmcmre. 

When the excessive mole fraction is increased to 0.19 (the corresponding pitch is 0.57 pm and the chirality is 1.75 pm ), BPII appears. The temperature range of BPII first increases with the 

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D.K. Yang, P.P. Crooker, Chiral-racemic phase diagrams of blue-phase liquid crystals. Phys. Rev. A 35, 4419-4423 (1987)... 

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