Frustrated smectic liquid crystal phases

Thermotropic liquid crystals, 15 86-98 bent-core, 15 98 discotic phases of, 15 96 frustrated phases of, 15 94-96 metallomesogens, 15 97 nematic liquid crystals, 15 86-92 smectic liquid crystals, 15 92-94 Thermotropic mesophases, 20 79 Thermotropic polycarbonates, 19 804 Thermotropic polyesters, liquid-crystalline, 20 34... 

J. Wang, The Frustrated Smectic Phases in Liquid Crystals , thesis. University of Pennsylvania, 1985. 

Although not specific of liquid crystals, the re-entrant phenomenon (i.e. re-appearance of the phase of higher symmetry upon cooling) is often observed in frustrated smectics [80,106]. Theoretical analyses suggest that there is no universal explanation for re-en-trance in the N-SmA problem. 

Liquid crystal molecules usually tilt in the same direction over the smectic layers (synclinic [212]) in the smectic C (SmC) phase. However, in one of the smectic A (SmA) phases, called de-Vries phase [213,214], molecules tilt but the tile direction is random so that the overall molecular tilt cannot be recognized optically. Frustration can be produced between aligning and random orders [215]. There is another style of tilt, in which the tilting direction is aligning in one direction in each smectic layer however, tilting direction alternates between the adjacent layers (anticlinic [212]). It has been well known that the introduction of chirality into the synclinic and anticlinic stmctures produces the ferroelectric and antiferroelectric properties, respectively. Frustration between the ferroelectric and antiferroelectric properties produces the ferroelectric structure in which the spontaneous polarization is partially canceled by the different magnitude between plus and minus polarization directions [216, 217]. The anticlinic order, NOT the antiferroelectric order, has been reported to be created by achiral systems [218, 219], indicating that the frustration between synclinic and anticlinic structures occurs, without any polar effects. The clinicity is determined by the style of the molecular order between the adjacent smectic layers, and therefore, the molecular structures at the peripheral... 

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