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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

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.

3

On the non-exponential degradation kinetics in topologically-disordered substances

Klym H., Balitska V., Shpotyuk O., Vakiv M.

Prace Naukowe. Chemia i Ochrona Środowiska / Akademia im. Jana Długosza w Częstochowie

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2005

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Vol. 10

33--43

EN

The peculiarities of non-exponential degradation kinetics in topological-disordered solids are analyzed. It was shown that degradation transformations, described by ideal exponential function, are determined by one value of activation energy independently to the structural dispersivity of the system, while the non-exponential degradation kinetics corresponds to stretched or suppressed exponential-power-like relaxation function. The stretched degradation kinetics is proper to own degradation transformations in one-type systems. The degradation transformations, including two or more different elementary processes, are described by suppressed kinetics.

4

Degradation of dynamic radiation-induced effects in chalcogenide vitreous compounds.

Balitska V., Shypotyuk O., Vakiv M.

Inżynieria Materiałowa

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2001

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R. XXII, nr 4

189-192

EN

The experimental results on time dependent changes of radiation-induced darkening effects in vitreous chalcogenide semiconductors of ternary stoichiometric (As2S3)y(GeS2)t-y and non-stoichiometric (As2S3)x(Ge2S3)t-x systems with variations of the average coordination number Z are discussed. We established that an adequate model for the quantitative description of these effects can be developed on the basis of bimolecular relaxation function appropriate for annihilation of specific structural defects in the form of oppositely charged atoms with anomal coordinations. The observed features of the investigated dynamic radiation-optical changes in these glasses are explained by their compositional dependences on atomic compactness, as well as covalent bond statistics.