Chevrons ferroelectrics

C1/C2 chevrons, ferroelectric devices 644 cadmium selenium TFT address 233 Cano wedge, chiral nematics 347 f, 351 Canon technology, ferroelectric devices 648 capillaiy flow, shear viscosity 143 carbocyclic compounds, charge transfer systems 958 carbocyclic rings, smectogens 412 carbon atoms, intercalated smectics 808 carbon-carbon bonds, dimers 823 carbon-carbon double bonds, chiral smectics 498 carbonaceous phases 693 carbonyl connectors, antiferroelectrics 687 carbonyl groups... 

Rieker T P, Clark N A, Smith G S, Parmar D S, Sirota E B and Safinya C R 1987 Chevron local layer structure in surface-stabilized ferroelectric smectic-C cells Phys.Rev.Lett 59 2658-61... 

Fig. 17a-c. Sketches of the molecular arrangements for the smectic structure with alternating layer-to-layer tilt a conventional and chevron smectic C layering in low molecular mass mesogens b ferroelectric hilayer chevron structures for achiral side-chain polymers c antiferroelectric hilayer chevron structures for achiral side-chain polymers. Arrows indicate the macroscopic polarization in the direction of the molecular tilt... 

The Tokyo Tech group assigned a C2 structure for the layers in the B2 phase, and ferroelectric packing of such layers to form a locally polar C2v macroscopic structure, as indicated in Figure 8.20. Other early workers in the field also adopted this structural model for the B2 phase. Brand et al. had discussed a C2 smectic chevron structure in their 1992 theoretical study,29 and while they seem to be referring to an all-anticlinic bilayer smectic, their actual graphic is basically identical to that shown in Figure 8.20. Furthermore,... 

It is interesting to point out here that with all of the theoretical speculation in the literature about polar order (both ferroelectric and antiferroelectric) in bilayer chevron smectics, and about reflection symmetry breaking by formation of a helical structure in a smectic with anticlinic layer interfaces, the first actual LC structure proven to exhibit spontaneous reflection symmetry breaking, the SmCP structure, was never, to our knowledge, suggested prior to its discovery. 

Figure 5.29 (a) Bookshelf geometry in a surface-stabilized ferroelectric liquid crystal (SSFLC) display showing two states of polarization. Here the surface acts to unwind the helix, (b) Chevron geometry in an FLC. This disturbs the switchable polarization in the bookshelf geometry... 

Ferroelectric liquid crystal devices have suffered from a number of characteristic alignment defects which are absent from nematic liquid crystal devices. The most important of these, termed zig-zag defects (from their characteristic shape) result from the chevron structure (Fig. 23). The chevron can form with the layer tilt toward either of the directions perpendicular to the layer planes if there is also a surface pretilt, its direction and that of the layer tilt may... 

Since very little is known about LCLC structures and properties, the recognition of these materials is not widespread. However, as one of the pioneers in the field, J. Lydon, writes "A single commercial application, however, could change this picture overnight. The liquid crystal literature will be as full of chromonic studies as it now is with ferroelectric chevron structures. Watch this space."... 

Using X-ray diffraction, the origin of the piezoelectricity was related to the presence of chevrons and the tilted orientation of the molecules. It is interesting to compare the values of the piezoelectric coefficients and spontaneous polarization (Ps - 8 nCVcm ) of this plasticized ferroelectric network with the respective values for the phase of PVDF,... 

In tbc ambitious JOERS/ALVEY Project, STC, Thom EMI, RSRE, BOH. and the University of Hull have joined to push forward the development of ferroelectric displays. A 10.4-in.-diagonai, VGA display with 8 colors and lO-Hz frame rale for laptop applications was presented [39]. Tb establish this technology the C2U chevron stale was selecicd and a high-frequency AC stabilization operating in tiK t-V minimum was used (31). 

A. Ptiknda, Y. Ouchi, H. And. R Ihkano, K. Ishikawa, and H. Ihkezoc. Cxwnpicxitics in the structure of ferroelectric liquid crystal cells. The chevron structure and twisted stales. Uq Cryst 5 1055 (1989). 

We have measured the viscosity [43, 44] and the electroclinic effect [45] of MHPOBC, but we did not mention a little abnormality of it in those papers. However, we have mentioned that the SmC may in fact be SmF or SmI in a footnote of [43]. In addition, we had inferred a third stable state, such as the one shown in Fig. 9.1, appears due to the effect of the polarization charge below a certain temperature in [44]. This structure was proposed by us on the bases of a chevron structure and was presented as a poster at the first international ferroelectric liquid crystal conference in 1987 [46]. This structure, however, was later replaced by the model of the antiferroelectrie liquid crystal phase. 

T.P. Rieker, N.A. Clark, G.S. Smith, D.S. Parmar, E.B. Sirota and C.R. Safinya, Chevron Local Layer Structure in Surface-Stabilized Ferroelectric Smectic-C Cells, Phys. Rev. Lett, 59, 2658-2661 (1987). 

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