L. Longa et al., NONLINEAR DIELECTRIC SUSCEPTIBILITY IN BLUE PHASES OF CHIRAL LIQUID-CRYSTALS, Molecular crystals and liquid crystals science and technology. Section A, Molecular crystals and liquid crystals, 303, 1997, pp. 237-247
The deformation of the cubic blue phase I along the field changes from
dilatation to compression or vice versa when the electric field vecto
r is rotated from one crystallographic direction to another. This phen
omenon is termed anomalous electrostriction and together with topology
of phase diagrams of the blue phases awaits elucidation. Standard the
ory of blue phases is not able to explain these observations. Followin
g the experiments of Pieranski et al. we generalized the standard theo
ry by incorporating a nonlinear dielectric susceptibility tensor (NDS)
. It is shown that the distortion of the cubic blue phase I in the pre
sence of the NDS may display the anomalous electrostriction, in accord
ance with experiment. These results seem to indicate that nonlinear su
sceptibility tensor is a relevant order parameter for the blue phases.