  Recent experiments probing a new ferroelectric liquid crystal (CLF08)
confined in cells with planar alignment have shown dielectric and optic
anomalies suggesting the onset of ferrielectric ordering within the surface
lattice of dechiralisation lines. We present a phenomenological theory
describing the corresponding phase transitions sequence SmA->SmC*->Ferri. Phase
diagrams, thermodynamic, dielectric and optic properties are worked out and
compared with experiments. The anomalies are related to the predicted
tristability of the experimental cells under applied electric field. The order
parameters of Landau theory are reinterpreted in terms of line positions,
allowing the description of the entrance/exit lines behavior, and yielding the
prediction and identification of new limit phases within a non-conventional
Landau approach.
