Evidence for a nematic-nematic transition in thin cells of a highly polar compound
- 1 November 1998
- journal article
- Published by IOP Publishing in Europhysics Letters
- Vol. 44 (3), 296-301
- https://doi.org/10.1209/epl/i1998-00473-7
Abstract
We report experimental evidence for a weak first-order nematic-nematic transition in thin ( ~ 1–2 μm) cells of the strongly polar nematogen, p-cyanophenyl p-n heptylbenzoate. The transition temperature TNN increases as the thickness of the cell decreases indicating that, in the bulk, this transition may occur at temperatures well below the ambient one. Optical and dielectric measurements of the order parameters in thin cells show that there is considerable enhancement compared to the bulk values. TNN can be increased significantly by moderate electric and magnetic fields. The transition probably indicates a jump in the concentration of neighbours with antiparallel configurations compared to those with parallel configurations. The results imply that the order parameter coherence length in the compound is relatively large.Keywords
This publication has 14 references indexed in Scilit:
- A simple molecular theory of the SmA nematic lake in highly polar compounds -SmA critical point and 1 dLiquid Crystals, 1997
- Biaxial nematic and smectic-A boundaries in thin planar samples of 8OCB aligned by rubbed polyimideEurophysics Letters, 1996
- Experimental Observation of a Transition between Two Uniaxial Nematic Liquid-Crystal PhasesPhysical Review Letters, 1994
- A simple molecular theory of a nematic–nematic phase transition in highly polar compoundsLiquid Crystals, 1993
- A simple molecular theory of double reentrance exhibited by highly polar compoundsLiquid Crystals, 1990
- Dislocation-loop melting theory of phase diagrams with nematic regions surrounded by smectic regionsPhysical Review A, 1987
- Boundary-layer phase transition in nematic liquid crystalsPhysical Review A, 1982
- The Re-entrant Nematic, Enhanced Smectic A Phases and Molecular CompositionMolecular Crystals and Liquid Crystals, 1981
- Refractive Indices and Orientational Order Parameter of Five Liquid Crystals in Nematic PhaseMolecular Crystals and Liquid Crystals, 1980
- X-Ray study of the reentrant polymorphism N-SA-N-SA in a pure liquid crystal compoundJournal de Physique, 1980