Wyniki wyszukiwania - Biblioteka Nauki

1

Radiation-induced paramagnetic centers in Bioglass(R).

100%

Padlyak B. , Szarska S. , Jungner H.

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2000

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tom Vol. 30, nr 4

709-717

EN

The X-band (v=9.4 GHz) electron spin resonance (ESR) and thermally stimulated luminescence (TSL) spectra of the UV-, X-, and gamma -irradiated Bioglass(R) samples of different composition (Bioglass(R) I and Bioglass(R) II) have been investigated. The efficiency of generation of electron and hole centers strongly depends on basic Bioglass(R) composition and is almost independent of ionizing radiation type and presence of Fe/sup 3+/ non-controlled impurity in the glass network. The spin Hamiltonian parameters (g and a values) and thermal stability of the radiation-induced centers have been evaluated. The results of TSL measurements show good agreement with ESR data. The energetic structure, formation peculiarities and specific models of the radiation-induced paramagnetic centers in the Bioglass(R) network are discussed.

2

Structure of CaO-Ga/sub 2/O/sub 3/-GeO/sub 2/ glasses: X-ray and molecular dynamics simulation studies.

75%

Padlyak B. , Mudry S. , Halchak V. , Korolyshyn A. , Rybicki J. , Witkowska A.

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2000

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tom Vol. 30, nr 4

691-699

EN

The X-ray scattering data for CaO-Ga/sub 2/O/sub 3/-GeO/sub 2/ glasses of stoichiometric compositions similar to that of calcium-gallium-germanium garnet (Ca/sub 3/Ga/sub 2/Ge/sub 3/O/sub 12/) Ca-gallogermanate (Ca/sub 3/Ga/sub 2/Ge/sub 4/O/sub 14/) and Ca/sub 3/Ga/sub 2/O/sub 6/ crystals are presented. Experimental results show the true glass structure of the compounds under investigation. A comparative analysis of the X-ray data for glasses and their crystalline analogies has shown that the glass network consists of gallium and germanium oxygen co-ordinated octahedra and tetrahedra. The results obtained have been compared with the results of preliminary molecular dynamics (MD) calculations of the structure of CaO-Ga/sub 2/O/sub 3/-GeO/sub 2/ glasses. The pair distribution functions (PDFs) obtained from the MD simulation, show satisfactory agreement with the X-ray data The building blocks of the CaO-Ga/sub 2/O/sub 3/-GeO/sub 2/ glass network have been proposed. The structure peculiarities of the glasses and their crystalline analogies are discussed.

3

Spectroscopy and high pressure spectroscopy of the Cr-doped glass materials.

75%

Grinberg M. , Borzowska J. , Padlyak B. , Nowosielski T. , Kukliński B. , Buchynski P.

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2000

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tom Vol. 30, nr 4

509-516

EN

Optical spectroscopy and high pressure optical spectroscopy of the Cr-doped glasses of CaO-Ga/sub 2/O/sub 3/-GeO/sub 2/ system have been used. The emission spectrum consists of the broad band at about 12700 cm/sup -1/ and the sharper band with maximum peak at 14495 cm/sup -1/ (the R line emission). We have attributed the R line luminescence to the octahedral strong field Cr/sup 3+/ sites in the microcrystallites whereas the broad band luminescence has been related to the chromium in the glassy phase.

4

EXAFS study of glasses of the CaO-Ga2O3-GeO2 system

75%

Chełstowski D. , Witkowska A. , Rybicki J. , Padlyak B. , Trapananti A. , Principi E.

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tom Vol. 33, nr 1

125-132

EN

X-ray absorption spectroscopy (XAS) measurements for Ca3Ga2Ge3O12 and Ca3Ga2Ge4O14 glasses are presented. In particular, the extended X-ray absorption fine structure (EXAFS) spectra are analysed and local neighbourhood of Ga and Ge atoms is described in detail. The Ge/Ga atoms neighbourhood in considered glasses is compared with the data available for corresponding crystals. Performed comparative crystal-glass structural analysis confirms correlation between crystalline and glassy structures of the Ca3Ga2Ge3O12 and Ca3Ga2Ge4O14 compounds. Our results provide several new detailed data, and some general suggestions on the CaO–Ga2O3–GeO2 glass structure.

5

Synthesis and optical spectroscopy of the lithium tetraborate glasses, doped with terbium and dysprosium

63%

Padlyak B. , Ryba-Romanowski W. , Lisiecki R. , Pieprzyk B. , Drzewiecki A. , Adamiv V. , Burak Y. , Teslyuk I.

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tom Vol. 42, nr 2

365-379

EN

A series of the Tb- and Dy-doped glasses with Li2O-2B2O3 (or Li2B4O7:Tb and Li2B4O7:Dy) composition were synthesised and their spectroscopic properties were investigated. The Li2B4O7:Tb and Li2B4O7:Dy glasses of high chemical purity and optical quality were obtained from corresponding polycrystalline compounds in the air using standard glass technology. The Tb and Dy impurities were added to Li2B4O7 composition in the form of Tb2O3 and Dy2O3 oxide compounds in amounts of 0.5 and 1.0 mol%. The electron paramagnetic resonance (EPR), luminescence excitation and emission spectra of the Li2B4O7:Tb and Li2B4O7:Dy glasses were investigated. On the basis of EPR and photoluminescence spectra analysis it was shown that the Tb and Dy impurities are incorporated in the Li2B4O7 glass network as Tb3+ (4f8, 7F6) and Dy3+ (4f9, 6H15/2) ions, exclusively. All observed transitions of the Tb3+ and Dy3+ centres in the luminescence excitation and emission spectra were identified. The luminescence kinetics shows single exponential decay for Tb3+ and Dy3+ centres in Li2B4O7 glasses. The lifetime values for main emission transitions of the Tb3+ and Dy3+ centres in the Li2B4O7 glasses containing 0.5 and 1.0 mol% Tb2O3 and Dy2O3 are determined at T = 300 K. Peculiarities of optical properties and local structure of the Tb3+ and Dy3+ centres in the Li2B4O7:Tb and Li2B4O7:Dy glasses as well as their potential applications have been discussed.