Theory of nematic–smectic phase separation in thin twisted liquid crystal cells
- Resource Type
- Authors
- J. R. Sambles; Mikhail A. Osipov; Lizhen Ruan
- Source
- Liquid Crystals. 30:823-830
- Subject
- Phase transition
Materials science
Biaxial nematic
Condensed matter physics
business.industry
Transition temperature
General Chemistry
Condensed Matter Physics
Condensed Matter::Soft Condensed Matter
Optics
Liquid crystal
Slab
General Materials Science
Twist
Deformation (engineering)
Whole cell
business
- Language
- ISSN
- 1366-5855
0267-8292
Recently it has been shown experimentally by the authors that a highly twisted thin nematic cell at low temperatures can separate into a smectic A region in the middle of the cell surrounded by twisted nematic layers at the boundaries. In this case the twist is expelled into the nematic layers and the nematic–smectic A transition temperature is strongly depressed. We present a thermodynamic theory of such a phase transition in a twisted nematic cell, taking into account that the smectic A slab inside the nematic cell can be stable only if the decrease of free energy in the smectic region overcomes the increase in distortion energy of the twist deformation in the nematic layers plus the energy of the nematic–smectic A interface. In such a system the equilibrium thickness of the smectic A slab corresponds to the minimum of the total free energy of the whole cell, which includes all the bulk and surface contributions. Existing experimental data are at least qualitatively explained by the results of the prese...