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1

Room Temperature Ferroelectric Mixture of Chiral and Achiral Thioesters

100%

Czerwiec J., Ossowska-Chruściel M., Chruściel J., Wróbel S.

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issue 4

549-552

EN

Dielectric properties of the mixture of two thioester compounds: 4-8-alkoxy-benzoate-thio-carboxyl S-4-pentyl-phenyl (8OS5), (s)-4-(1-methyl-heptyloxy)biphenyl-4-thio-carboksyl 4-9-alkil-phenyl (MHOBS9) are presented. The chiral compound exhibits nematic (N*) and ferroelectric smectic C* phase (SmC*). The achiral compound shows N, SmA and monotropic SmC and SmB phases. the mixture of both compounds of 0.5 molar fraction shows SmC* in the wider temperature range than pure MHOBS9. The mixture was studied using frequency domain dielectric spectroscopy. Dielectric measurements for the SmC* phase of the mixture revealed Goldstone mode at higher frequencies and Maxwell-Wagner relaxation at low frequencies.

2

Dielectric Properties of Ferroelectric Liquid Crystals with Diversified Molecular Structure - ERRATUM

88%

Czerwiec J., Dąbrowski R., Żurowska M., Ziobro D., Wróbel S.

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issue 6

978

3

Dielectric Properties of Ferroelectric Liquid Crystals with Diversified Molecular Structure

88%

Czerwiec J., Dąbrowski R., Żurowska M., Ziobro D., Wróbel S.

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issue 4

553-556

EN

Mesomorphic, thermodynamic, electro-optic and dielectric properties of three homologues of fluorosubstituted esters are described. Full chemical names of these compounds are as follows: (S)-(+)-4-(1-metyl-hepty-loksy)benzoate-(6-penta-fluoro-propano-ynloxyhex-1-oxy)-biphenyl-4-yl (in short 2F6BBiOC8), (S)-(+)-4-(1-metyl-hepty-loksy)benzoate-(6-nona-fluoro-pentano-yloxyhex-1-oxy)-biphenyl-4-yl (in short 4F6BBiOC8), (S)-(+)-4-(1-metyl-hepty-loksy)benzoate-(6-trideca-fluoro-heptano-yloxyhex-1-oxy)-biphenyl-4-yl (in short 6F6BBiOC8). The compounds exhibit ferroelectric smectic C* phase between crystalline and isotropic phase. Only one compound (6F6BBiOC8) shows antiferroelectric phase (SmC*_{A}) observed by dielectric spectroscopy, but the range of this phase is narrow of about 2°. All three compounds exhibit in the SmC* phase Goldstone mode and Maxwell-Wagner relaxation hidden in the conductivity contribution at low frequencies, whereas in the SmC* _{A} phase two anti-ferroelectric modes (AFM1) and (AFM2) contribute to the dielectric spectrum. The compounds were studied using differential scanning calorimetric, frequency domain dielectric spectroscopy, and reversal currents method to determine spontaneous polarization.

4

Polymorphism of Chiral Thioester Studied by Dielectric Spectroscopy

52%

Wawrzyniak A., Chruściel J., Douali R., Dubois F., Leblond J., Legrand C., Ossowska-Chruściel D., Marzec M., Ropa P., Czerwiec J., Wróbel S.

Acta Physica Polonica A

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2013

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vol. 124

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issue 6

933-936

EN

(S)-(+)-4'-[(4-(1-methylheptyloxycarbonylphenyl) thiocarbonylphenyl]-decyloxybenzoate (in short 10.OPOSMH) was studied by complementary methods. The substance shows rich polymorphism. In addition to ferroelectric and antiferroelectric smectic C* phases it possesses three ferrielectric sub-phases. Phase transitions between the phases were revealed by differential scanning calorimetry and static dielectric permittivity measurements. The aim of this paper was to study phase transitions and differences in dielectric spectra shown by different phases. Collective and molecular dynamics of all phases shown by 10.OPOSMH will be discussed in terms of theoretical models. Dielectric spectra of antiferroelectric phase show two characteristic dielectric relaxation modes: one connected with the molecular process (reorientation around the short axis) and the other originating from fluctuations of antiferroelectric order parameters.

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4 Acta Physica Polonica A

1 2013

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4 Wróbel S.

2 Chruściel J.

2 Dąbrowski R.

2 Ziobro D.

2 Żurowska M.

1 Douali R.

1 Dubois F.

1 Leblond J.

1 Legrand C.

1 Marzec M.

1 Ossowska-Chruściel D.

1 Ossowska-Chruściel M.

1 Ropa P.

1 Wawrzyniak A.

Room Temperature Ferroelectric Mixture of Chiral and Achiral Thioesters

Dielectric Properties of Ferroelectric Liquid Crystals with Diversified Molecular Structure - ERRATUM

Dielectric Properties of Ferroelectric Liquid Crystals with Diversified Molecular Structure

Polymorphism of Chiral Thioester Studied by Dielectric Spectroscopy