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1
Content available Azopolyimides – influence of chemical structure on azochromophore photo-orientation efficiency
Konieczkowska J., Kozanecka-Szmigiel A., Piecek W., Węgłowski R., Schab-Balcerzak E.
Polimery
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2018
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T. 63, nr 7-8
481--487
EN
This work is a summary of our previous investigations of polyimides containing derivatives of azobenzene or azopyridine. Here we discussed the relationship between the microstructure of azopolyimides and azochromophore photo-orientation efficiency determined in measurements of photoinduced birefringence as well as the relationship between the microstructure ofazopolyimides and their selected physical properties. The designed architecture of azopolymers allowed to trace the effect of such structural elements as the structure of the polymer main chain and chromophore, its content, location including the method of dye assembling with the polymer matrix on thermal, optical and photoinduced properties. We also discussed the possibility of the intermolecular hydrogen bonds formation in functionalized azopolyimides, which hinder isomerization of the azobenzene molecules results the photoinduced birefringence is not observed in the material. Additionally, the possibility of potential applications of azopolyimides as layers for the liquid crystal alignment was presented.
PL
Artykuł stanowi podsumowanie naszych badań dotyczących azopoliimidów zawierających pochodne azobenzenu lub azopirydyny. Przedstawiono zależność między budową azopolimerów a efektywnością fotoorientacji azochromoforów, określaną na podstawie mierzonej fotoindukowanej dwójłomności, z uwzględnieniem wpływu struktury na wybrane właściwości fizyczne. Przedmiotem rozważań były azopolimery o odpowiednio zaprojektowanej budowie chemicznej pozwalającej na określenie wpływu struktury łańcucha głównego polimeru, a także chromoforu, jego zawartości i sposobu przyłączenia oraz lokalizacji w merze polimeru na właściwości termiczne, optyczne i fotoindukowane światłem spolaryzowanym. Omówiono także możliwość tworzenia w poli­merach funkcjonalizowanych międzycząsteczkowych wiązań wodorowych, które hamują izomeryzację grup azobenzenowych, w wyniku czego nie obserwuje się generowania fotoindukowanej dwójłomności w materiale. Przedstawiono ponadto badania aplikacyjne, które wykazały możliwość porządkowania mieszaniny ciekłokrystalicznej za pomocą warstw otrzymanych z wybranych azopoliimidów.
2
Content available remote Electro-optic activity of an azopolymer achieved via poling with the aid of silicon nitride insulating layer
Kozanecka-Szmigiel A., Szmigiel D., Switkowski K., Schab-Balcerzak E., Siwy M.
Optica Applicata
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2011
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Vol. 41, nr 3
777--785
EN
Nonlinear optical chromophore was synthesized to form a guest-host system with a PMMA matrix. Thin polymer films were spin-coated onto the substrates containing an additional insulating layer. The layer material was high resistivity and high transmittance silicon nitride obtained by chemical vapour deposition with plasma enhancement at a relatively low temperature of 150 °C. The presence of the nitride layer allowed for performing the polymer poling in the range of high electric field strengths not attained in structures without the insulating layer. Here, for the first time to the best of our knowledge, the silicon nitride interlayer was used in the poling process.
3
Content available remote Investigations of photoresponse signals of LT-GaAs photodetector
Białous M., Świtkowski K., Kozanecka-Szmigiel A., Wierzbicki M., Pura B.
Optica Applicata
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2009
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Vol. 39, nr 1
161--167
EN
In this paper, we demonstrate our electro-optic sampling system constructed for characterization of high-speed photodetectors based on low-temperature-grown GaAs (LT-GaAs). Changes in the shape of electrical signals for different optical powers, voltage biases and positions of a probe beam have been shown. The obtained photoresponse of the investigated photodetector exhibits 0.9 ps (full width at half maximum).
4
Content available remote Structure and electrical properties of oxide-ion conductors in the Bi3NbO7-Bi3YO6 system
Kozanecka-Szmigiel A., Krok F., Abrahams I., Wrobel W., Chan S.C.M., Dygas J.R.
Materials Science Poland
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2006
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Vol. 24, No. 1
31--37
EN
A study of the structure and electrical conductivity of Bi3Nb1-xYxO7-x is presented. X-ray diffraction confirms full solid solution formation in this system, with the adoption of a fluorite-type structure. Superlattice ordering of the anion sublattice is evident in neutron diffraction data, the nature of which varies with composition. At low values of x, long-range ordering is present, whereas above x = 0.4 only local ordering is observed. Arrhenius plots of the total electrical conductivity of all samples containing yttrium show two linear regions with different activation energies, with evidence for a phase transition between 450 and 680 °C.
5
Content available remote Oxide-ion conductors for fuel cells
Krok F., Abrahams I., Wrobel W., Kozanecka-Szmigiel A., Dygas J.R.
Materials Science Poland
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2006
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Vol. 24, No. 1
13--22
EN
The principal materials used in the construction of solid oxide fuel cells (SOFCs) are discussed. Some of the problems encountered with high temperature fuel cells (HT-SOFCs) might be overcome by lowering the operating temperature to 500-700 °C, through the development of suitable materials for intermediate temperature fuel cells IT-SOFCs. Candidate electrolyte materials are discussed, including cerium gallium oxide, lanthanum strontium gallium magnesium oxide, and electrolytes based on doped bismuth oxide. While high ionic conductivities can readily be achieved in these materials at intermediate temperatures, stability in reducing atmosphere is still a problem. This might be overcome by careful chemical design of electrolytes containing stabilising dopants. Two zirconia-doped bismuthate systems are discussed in this respect. In both cases, the obtained materials exhibit different structures - one is Bi3Nb1-xZrxO7-x/2 of the ?-Bi2O3 type, and the other, Bi4V2-2xZrxO11-x, has a layered structure of the Aurivillius type.
6
Content available remote Bi8V2O17 - a stable phase in the Bi2O3-V2O5 system
Wrobel W., Krok F., Abrahams I., Kozanecka-Szmigiel A., Malys M., Chan S.C.M., Dygas J.R.
Materials Science Poland
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2006
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Vol. 24, No. 1
23--30
EN
Bi8V2O17 is commonly observed as an intermediate phase in the synthesis of compounds in ternary systems of the type Bi2O3-V2O5-MexOy. It is also seen as an end product at particular compositions in these systems. A rhombohedral substructure model for this phase is presented along with electrical parameters. Evidence from the Arrhenius plot suggests a phase transition at around 550 °C. The existence of a limited solid solution of Bi8V2O17 with ZrO2 is also discussed.
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