Smectic F phase

This region has been divided into two subphases, L and S. The L phase differs from the L2 phase in the direction of tilt. Molecules tilt toward their nearest neighbors in L2 and toward next nearest neighbors in L (a smectic F phase). The S phase comprises the higher-ir and lower-T part of L2. This phase is characterized by smectic H or a tilted herringbone structure and there are two molecules (of different orientation) in the unit cell. Another phase having a different tilt direction, L, can appear between the L2 and L 2 phases. A new phase has been identified in the L 2 domain. It is probably a smectic L structure of different azimuthal tilt than L2 [185]. 

Cr, crystalline phase SmC, smectic C phase SmF, smectic F phase SmX, unidentified smectic phase 1, isotropic liquid dec., decomposition. ... 

FIGURE 21 Ordered tilted smectic phases (a) smectic F phase (b) smectic H phase. The smectic 1 phase has the same structure as smectic F but another tilt direction (not along the prism face but along the prism edge). 

The structure of the chiral smectic F phase is similar to that of the chiral smectic I phase, except that the tilt direction is towards the side of the local hexagonal packing net, rather than towards the apex. 

The smectic F phase can also be considered as a tilted hexatic phase similar to the smectic I phase, the difference between the two phases lying in the direction of the long molecular axes with respect to the two-dimensional arrangement within the smectic layers [151]. Calorimetric and X-ray diffraction studies of several compounds of the homologous TBnA series carried out around the SmC-SmF transition clearly indicate the first order nature of the corresponding transition, with, in particular, a jump in the... 

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