Smectic transitions between them

We do not give a detailed classification of the types of liquid crystals, since the systems under consideration mainly form nematic or in some cases cholesteric phase. The latter phase belongs, in principle, to the same range of liquid crystals as the nematic phase, since there is no phase transition between them (unlike smectic-nematic phase transition). 

In the smectic B phase, the molecules within the layers are aligned perpendicularly to the layers, but the molecules of the Sp and Si phases within layers are tilted with respect to the layer normal by a tilt angle. The azimuthal of the tilt direction or the projections onto the smectic layers of the Sp and Si phases are different. In the former, the projections of molecules onto the layer point to the edge of the hexatic, while in the latter, to the apex. The difference seems not so significant, but Sp and Si liquid crystals are not miscible, and there is a phase transition between them when the temperature varies. 

The blue phase was earlier classified as belonging to the cholesteric phase, but is in fact a separate phase. It is in a sense a crystalline liquid. The molecules are positionally disordered and have no fixed mean positions, but the spatial pattern of molecular orientations can be assigned to a translation group. Usually the blue phase falls between the cholesteric and the isotropic phase, but direct transition to the smectic phase has been observed. Three blue phases have been found, one of them is amorphous. 

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