Stimulation of the Electrohydrodynamic Instability in the Smectic a Phase

Chirkov, V. N.; Aliev, D. F.; Radshabov, G. M.; Zeinally, A. Kh.

doi:10.1080/00268947908070465

Cited by 21 publications

(15 citation statements)

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“…7,8 For 8CB, at 22°C, the value of the dielectric anisotropy, ⌬ ͑= ʈ − Ќ ͒ was found to be 8.4. This compound has the phase sequence: crystal to S A at 21.1°C, S A to nematic at 33.5°C and nematic to isotropic at 40.1°C.…”

Section: Resultsmentioning

confidence: 96%

“…The theoretical predictions require further investigation, since for example, the cell thickness dependencies found experimentally disagree. 4,7,8 In the organosiloxane compounds, a doping level of 0.01% w/w CTAB is used. 4 This is in agreement with other workers.…”

Section: Correspondence With Electro-optic Resultsmentioning

confidence: 99%

“…This is not surprising, since factors such as the surface roughness of the ITO-coated electrodes, the nature of the ionic dopant used, and the definition of threshold voltage have an effect 7,19. A general result, however, is that for 8CB the ratio V write / V erase Ͼ 1 7,8. Possibly, this is indicative of a very smooth ITO coating in these cells.…”

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confidence: 89%

“…This is a consequence of the multiblock nature of these covalently bonded compounds; they consist of three chemically distinct parts, i.e., the mesogenic core, the hydrocarbon chains, and the siloxane moiety, that, in their pure form, are mutually immiscible in the absence of a solvent. 7,8 This device offers advantages over conventional liquid crystal displays with similar polarizer-free operation ͓e.g., the polymer dispersed liquid crystal ͑PDLC͒ device͔ 9 since both modes are stable and there is minimal haze in the clear state ͑i.e., they have a wide viewing angle͒. 6 In this paper, we are mainly concerned with characterization of siloxane liquid crystals in the context of the electrically addressed bistable S A display.…”

Section: Introductionmentioning

confidence: 99%

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Highly anisotropic conductivity in organosiloxane liquid crystals

Gardiner

Coles

2006

Journal of Applied Physics

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Articles you may be interested inA field-induced ferrielectric liquid crystal phase Appl. Phys. Lett. 98, 043501 (2011); 10.1063/1.3545847Memory effect near transition temperature in Sm C phase in nonsurface stabilized ferroelectric liquid crystalsIn this paper, we present the conductivity and dielectric characterization of three homologous series of smectic A siloxane containing liquid crystals. The materials studied include one monomesogenic series, which consists of a 4-͑-alkyloxy͒-4Ј-cyanobiphenyl unit terminated by pentamethyldisiloxane, and two bimesogenic series, which consist of twin 4-͑-alkyloxy͒-4Ј-cyanobiphenyls joined via tetramethyldisiloxane or decamethylpentasiloxane. All of the compounds exhibit wide temperature range enantiotropic smectic A phases; the effect of the siloxane moiety is to suppress nematic morphology even in the short chain homologs. We find that these compounds exhibit a highly anisotropic conductivity: the value perpendicular to the director is to up to 200 times that parallel to the director. For the nonsiloxane analog 4-͑-octyl͒-4Ј-cyanobiphenyl ͑8CB͒, this value is approximately 2. It is also found that the dielectric anisotropy is reduced significantly; a typical value is ϳ1 compared to 8.4 for 8CB. We propose that the origin of these unusual properties is in the smectic structure; the microphase separation of the bulky, globular siloxane moieties into liquidlike regions severely inhibits the mobility parallel to the director and across the smectic layers. Further, the inclusion of this unit acts to increase the antiparallel correlations of molecular dipoles in the aromatic and alkyloxy sublayers, reducing the dielectric anisotropy significantly compared to nonsiloxane analogs. The highly anisotropic conductivity suggests that these materials are particularly suitable for application in electro-optic effects which exploit this property, e.g., the bistable electro-optic effect in smectic A liquid crystals.

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Section: Resultsmentioning

confidence: 96%

Section: Correspondence With Electro-optic Resultsmentioning

confidence: 99%

mentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

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Highly anisotropic conductivity in organosiloxane liquid crystals

Gardiner

Coles

2006

Journal of Applied Physics

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“…Temperature dependences of the electroconductivity components o ,~ and uL (1,3) and of the electroconductivity anisotropy of oL /oil as well as the dielectric anisotropy (4).flow of the medium near the electrode regions on the thickness of the Debye distance, L D . It is confirmed by the circular motion perpendicular to the optic axis of foreign particles specially doped into the liquid crystal.…”

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confidence: 99%