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1

Non-linear electrooptic effect in antiferroelectric liquid crystal

Dardas D., Kuczyński W., Hoffmann J., Jeżewski W., Nowicka K. K., Małecki J.

Opto-Electronics Review

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2009

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Vol. 17, No. 1

25-29

EN

Electrooptic phenomena caused by weak electric fields, much lower than those needed for the helix unwinding, in helical smectic liquid crystals were studied in thin planar samples. The investigations were performed in chiral liquid crystal 4-(1-methyl-heptyloxycarbonyl) phenyl 4'-(3-butanoyloxy propyl-1-oxy) biphenyl-4-carboxylate which exhibits antiferro-electric properties. We have found that electric field applied to a helical smectic liquid crystal caused two effects. First, the helix was deformed and the position of effective optic axis changed by an angle proportional to the field strength. The second effect, quadratic in field, causes the change in the shape of the indicatrix. As a consequence, the relative changes in the light intensity caused by external electric field consist of two components. The first component represents the modulation with the fundamental frequency and the second one with the doubled frequency (second harmonic of the electrooptic effect). The ab- solute values of the first- and second-order electrooptic coefficients have been determined and their temperature dependence discussed.

2

Liquid-crystalline properties of 4-alkyl-, 4-alkyloxy and 4-halogene-4'-hydroxyazobenzene alkyloates

Trzaska J., Galewski Z.

Opto-Electronics Review

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2009

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Vol. 17, No. 2

129-139

EN

Twenty one esters, 4-alkyl-, 4-alkyloxy-, 4-nitro- and 4-halogene-4'-hydroxyazobenzne alkyloates have been synthesised. Basing on the DSC calorimetry and polarizing microscopy liquid- crystalline polymorphism was investigated. Five types of mesophases were identified: nematic, smectics A, C, F and unknown X (probably G).

3

Influence of the smectic standart's polarity on their stability in mixtures with 4-decyloxybenzylidene-4'-alkyloxyanilines

Godzwon J., Sienkowska M. J., Galewski Z.

Scientific Bulletin. Physics / Lodz University of Technology

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2006

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Vol. 26

29-37

EN

This paper describes synthesis and liquid crystalline properties of the homologous series of 4-decyloxybenzylidene-4'-alkyloxyanilines. On the basis of the polarization microscopy (POM, TOA) and the calorimetric (DSC) measurements a rich polymorphism has been detected. Investigated compounds have the following phases: nematic, smectic A, smectic C, smectic B, smectic I and smectic G. The presence of these mesophases has been confirmed by the miscibility method, using a mesophase reference 4-heptyloxybenzilidene-4'-pentyloaniline. Seven other smectic standarts with different polarity has been applied for search mesophase stability.

PL

W pracy przedstawiono wyniki badań właściwości ciekłokrystalicznych pełnego szeregu homologicznego 4-decykloksybenzylideno-4'-alkiloksyanilin. Metodami kalorymetrii DSC oraz mikroskopii polaryzacyjnej POM określono ilościowo parametry przejść fazowych oraz zidentyfikowano występujące mezofazy (w oparciu o metodę współmieszalności Sackmanna-Demusa). Zbadano pięć diagramów fazowych pochodnych badanego szeregu z wzorcem mezofaz, 4-heptyloksybenzylideno-4'-pentyloaniliną, które potwierdziły obecność sześciu mezofaz: N, SmA, SmC, SmB, SmI, i SmG. Zbadano również wpływ polarności wzorca (7 związków) na stabilność występujących mezofaz oraz na położenie punktów potrójnych pochodnej 4-decyloksybenzylideno-4'-propyloksyaniliny.

4

Non-linear electrooptical effects in chiral liquid crystals

Dardas D., Kuczyński W.

Opto-Electronics Review

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2004

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Vol. 12, No. 3

277-280

EN

We studied the electrooptical effects in ferroelectric liquid crystals at both the fundamental and the second harmonic frequency. The linear effects caused mainly by the changes in optic axis position give rise to the changes in the intensity of light passing the sample placed between crossed polarizers. The electric field causes also changes in the shape of the indicatrix. Both mentioned effects influence the second harmonic response. We observed that the defects present in ferroelectric liquid crystal sample affect the electrooptical response to a large extent. This influence is especially significant for the second order harmonics. The depth of light modulation depends on kind of alignment (bookshelf or chevron).