R. Ellinghaus and W. Muschik
Theoretical Reasons for the Thermodynamic Stability
of a Blue Phase of Trigonal Symmetry
Mol. Cryst. Liq. Cryst. 198, 1991, 73-78
Starting out with a special trigonal ansatz for the alignment tensor
field of a cholesteric liquid crystal we prove by using Landau theory
that this ansatz has a lower free-energy density than the cholesteric
phase and the O5-phase discussed by Grebel et al. [H. Grebel,
R. M. Hornreich, and S. Shtrikman, Landau theory of cholesteric blue
phases. Phys. Rev. A 28 <\b>: 1114, 1983], in a certain region of
the reduced temperature-chirality-plane. In this domain the trigonal
phase may be the thermodynamically stable one. Using an extension of
this ansatz we get an iimplicit equation for the interplanar spacing
of certain lattice planes as a function of an external electric
field. Therefor we are able to discuss electrostrictive effects of
this trigonal phase.