BazTech - Yadda

1

Positron trapping in functional spinel-type oxide ceramics.

Klym H., Balitska V., Shpotyuk O. I., Ingram A.

Archives of Materials Science

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2006

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Vol. 27, nr 4

177-187

EN

Positron trapping is studied in functional spinel-type oxide MgAl2O4 and Cu0,4Co0,4Ni0,4Mn1.8O4 ceramics using positron annihilation lifetime spectroscopy. Obtained results are treated in terms of multi-exponential model of positron spectrum involving both positron trapping and ortho-positronium decaying. Crystallographical specifity of spinel structure reflects on the shortest lifetime component, while the middle component corresponds to the vacancy-like defects near boundaries. It is shown that in the cases of humidity-sensitive MgAl2O4 ceramics the positron trapping parameters in defects near grain boundaries occurs more efficiently in water-moistened ceramics.

2

Positron trapping in chalcogenide glasses: a comparison between arsenic sulphide and selenide.

Shpotyuk O. I., Filipecki J., Kozdras A., Popescu M., Hyla M.

Archives of Materials Science

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2006

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Vol. 27, nr 4

167-175

EN

Positron annihilation lifetime measurements are performed for stoichiometric arsenic suphide. It is shown that two-state positron trapping model is valid for this glass as it has been shown previously for stoichiometric arsenic selenide. Two-component fitting parameters of LT computer program, describing positron annihilation in glassy As2S3, are close to those of glassy As2Se3. They are in good agreement with theoretically calculated distribution of nanovoid radii in these materials.

3

On the non-exponentionality in degradation kinetics in functional ceramics.

Balitska V., Shpotyuk O. I.

Archives of Materials Science

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2006

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Vol. 27, nr 4

189-199

EN

The peculiarities of non-exponential degradation kinetics Cu0.1Ni0.1Co1.6Mn1.2O4 ceramics are analyzed. It is shown that degradation kinetics in above materials, described by non-exponential function, corresponds to stretched or suppressed exponential-power relaxation function. The stretched degradation kinetics is proper for degradation transformations of one-type systems. The degradation transformations, including two or more different elementary processes, are described by supressed exponentional kinetics.

4

A unified model of physical ageing in chalcogenide glasses.

Shpotyuk O. I., Golovchak R. Y., Kozdras A., Szymura S.

Archives of Materials Science

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2006

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Vol. 27, nr 4

143-158

EN

Physical ageing processes in As(Ge)-Se glasses are analyzed using the chains crossing model and the constraints theory. It is shown that short-term physical ageing in these materials is fully determined by elementary relaxation acts of inner Se atoms within Se chains leading to the straightening of the latter with further shrinkage of glass matrix. Long term physical ageing is associated with pure shrinkage of under-constrained glass network. Phenomenological model of physical ageing in As(Ge)-Se glasses is developed to explain its compositional behaviour. The main statements of the model are verified by differential scanning calorimetry for chalcogenide glasses of As-Se family.

5

On the microstructural origin of reversible photoinduced transformations in amorphus As₂Se₃

Shpotyuk O. I.

Opto-Electronics Review

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2003

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Vol. 11, No. 1

19-25

EN

A microstructural mechanism of photoinduced structural transformations in amorphous As₂Se₃ thin films was studied by IR Fourier-transform spectroscopy in the range of 300-100 cm⁻¹. It was shown that the stage of irreversible photostructural changes in the freshly-deposited films was connected with coordination of topological defects formation accompanied by homopolar chemical bonds switchings in heteropolar ones. By contrast, the reversible stage of photoinduced effects were caused by two different types of transformations-heteropolar bonds switching in homopolar ones, as well as heteropolar bridge bonds switching in short layer ones. Both processes were associated with the formation of anomalously coordinated topological defect pairs and atomic displacements at the medium-range ordering level.

6

Physical peculiarities of electron-induced dichroism in vitreous As2S3

Shpotyuk O. I., Balitska V. O.

Prace Naukowe. Chemia / Wyższa Szkoła Pedagogiczna w Częstochowie

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1999

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Vol. 4

193--202

EN

The effect of dichroism (transmission coefficient difference for sonde light with parallel and perpendicular orientation of the polarization plane) was investigated in vitreous As2S3 irradiated by accelerated electrons (E=2,8 MeV) with more than 5 ˖ 1015 cm -2 fluences.

PL

Badano elektronowo indukowany dichroizm (różnica współczynnika przepuszczania światła o równoległej i prostopadłej orientacji płaszczyzny polaryzacji) szklistego As2S3 przy napromieniowaniu przyspieszonymi elektronami (E = 2,8 MeV) o strumieniu powyżej 5 ˖ 1015 cm-2.