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1

EPR spectroscopy of Cu2+ and Mn2+ in borate glasses

Drzewiecki A., Padlyak B., Adamiv V., Burak Y., Teslyuk I.

Nukleonika

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2013

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Vol. 58, No. 3

379--385

EN

Electron paramagnetic resonance (EPR) spectra of the CaB4O7 and LiCaBO3 glasses containing 0.5 and 1.0 mol.% CuO and MnO2 impurity compounds were investigated at room temperature. The glasses with CaB4O7:Cu, LiCaBO3:Cu, CaB4O7:Mn and LiCaBO3:Mn compositions were produced from the corresponding polycrystalline compounds using standard glass synthesis and technological conditions developed by the authors. The EPR spectral parameters of the Cu2+ and Mn2+ centres in both glasses containing 0.5 and 1.0 mol.% CuO and MnO2 doping oxides were determined. Analysis of EPR spectral parameters shows that Cu impurity is incorporated into the CaB4O7 and LiCaBO3 glass network as isolated Cu2+ (3d9, 2D5/2) paramagnetic ions. The Cu2+ ions occupy Ca(Li) sites of the borate glass network coordinated by six O2− anions with geometry of elongated octahedron (D4h symmetry) due to the Jahn- -Teller effect. The EPR spectra of the Mn-doped CaB4O7 and LiCaBO3 glasses are virtually identical and typical of all oxide glasses activated with Mn2+ (3d5, 6S5/2) ions. Observed EPR spectra in the Mn-doped glasses were attributed to isolated Mn2+ (1) centres (geff ≅ 4.3) in octahedral Ca(Li) sites with a strong (fully) rhombic distortion, isolated Mn2+ (2) centres (geff ≅ 2.0) in octahedral Ca(Li) sites with nearly cubic local symmetry as well as pairs and small clusters of the Mn2+ ions, coupled by magnetic dipolar and exchange interactions. On the basis of the obtained results and analysis of referenced data, the local structure of the Cu2+ and Mn2+ centres in the borate glasses have been proposed.

2

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

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

Optica Applicata

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2012

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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.

3

Synthesis and optical spectroscopy of the Eu- and Pr-doped glasses with SrO–2B2O3 composition

Padlyak B., Grinberg M., Kuklinski B., Oseledchik Y., Smyrnov O., Kudryavtcev D., Prosvirnin A.

Optica Applicata

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2010

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Vol. 40, nr 2

413--426

EN

A series of Eu- and Pr-doped glasses with SrO–2B2O3 (or SrB4O7) composition were obtained and their spectroscopic properties were investigated. The SrB4O7 polycrystalline compounds were synthesised at T = 1300 K using high purity strontium carbonate (SrCO3) and boric acid (H3BO3). The Eu and Pr impurities were added to SrB4O7 compounds as Eu2O3 (amount: 0.167 at.%) and Pr2O3 (amounts: 0.05 and 0.25 at.%) oxides. The glass samples of high chemical purity and optical quality were obtained from corresponding polycrystalline compounds in the air atmosphere in platinum crucibles according to standard glass technology. Optical absorption, luminescence excitation and emission spectra of the Eu- and Pr-doped glasses with SrO–2B2O3 composition were investigated in the spectral range 300–800 nm at temperatures of 293 and 85 K. On the basis of optical spectra obtained and electron paramagnetic resonance (EPR) data analysis it is shown that Eu and Pr impurities are incorporated into the SrO–2B2O3 glass network as Eu3+ (4f6, 7F0) and Pr3+ (4f2, 3H4) ions, exclusively. All the observed transitions of the Eu3+ and Pr3+ centres in absorption and luminescence spectra were identified. The luminescence kinetics of Eu3+ and Pr3+ centres were investigated and analysed. The decay constants for main emission transitions in all samples investigated were obtained at room temperature. Peculiarities of incorporating the Eu3+ and Pr3+ activator ions in the glass with SrO–2B2O3 composition and their optical spectra are discussed in comparison with rare-earth doped polycrystalline compounds and single crystals with the same (SrB4O7) composition and other borate glasses.

4

Optical spectra and luminescence kinetics of the Sm3+ and Yb3+ centres in the lithium tetraborate glasses

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

Optica Applicata

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2010

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Vol. 40, nr 2

427--438

EN

Optical absorption, luminescence excitation, and emission spectra as well as luminescence kinetics of the Sm- and Yb-doped glasses with lithium tetraborate (Li2B4O7) composition were investigated and analysed. The Sm- and Yb-doped lithium tetraborate glasses of high optical quality were obtained in air from corresponding polycrystalline compounds according to standard glass synthesis technology. The Sm and Yb impurities were added to the Li2B4O7 compound in the form of Sm2O3 and Yb2O3 oxides in amount of 0.4 mol%. Using optical and electron paramagnetic resonance spectroscopy it was shown that the Sm and Yb impurities are incorporated into the lithium tetraborate glass network as Sm3+ (4f5, 6H5/2) and Yb3+ (4f13, 2F7/2) ions, exclusively. All of the observed transitions in the absorption and luminescence spectra of Sm3+ and Yb3+ centres were identified. The luminescence kinetics of the Sm3+ and Yb3+ centres in the Li2B4O7 glass are characterised by a single exponential decay. Decay constants for the main emission transitions of the Sm3+ and Yb3+ centres in the lithium tetraborate glass were obtained at T = 300 K. Incorporation peculiarities and optical spectra of Sm3+ and Yb3+ ions in the lithium tetraborate glass have been discussed in comparison with other borate glasses and crystals.

5

Optical spectroscopy and local structure of the Nd3+ luminescence centres in glasses of the CaO-Ga2O3-GeO2 system

Padlyak B., Ryba-Romanowski W., Lisiecki R.

Optica Applicata

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2008

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Vol. 38, nr 1

189-202

EN

Optical absorption and luminescence spectra as well as luminescence kinetics of the Nd3+ centres in glasses with Ca3Ga2Ge3O12:Nd composition, containing 0.2 and 1.0 wt% of the Nd2O3 were presented and analysed. The oscillator strengths and phenomenological intensity parameters omega t (omega 2, omega 4, and omega 6) were obtained using standard Judd-Ofelt theory. Calculated omega t parameters, radiative transitions rates, branching ratios and radiative lifetime for Nd3+ centres in the glass with Ca3Ga2Ge3O12 composition were analysed and compared with corresponding Nd3+ parameters in their crystalline analogue with garnet structure. Experimental lifetimes are compared with those calculated, and quantum efficiency of Nd3+ centres from 4F3/2 emitting level in the glass with Ca3Ga2Ge3O12 composition is estimated. Incorporation peculiarities and local structure of Nd3+ luminescence centres in the glass with Ca3Ga2Ge3O12 composition and corresponding Ca3Ga2Ge3O12:Nd3+ garnet laser crystals are considered. On the basis of extended X-ray absorption fine structure (EXAFS) spectra (L3-edge) of rare-earth elements analysis it has been shown that Nd3+ luminescence centres in the CaO-Ga2O3-GeO2 glass network occupy structural sites with the coordination number to oxygen N = 6.

6

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

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

Optica Applicata

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2003

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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.

7

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

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

Optica Applicata

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2000

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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.

8

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

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

Optica Applicata

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2000

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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.

9

Radiation-induced paramagnetic centers in Bioglass(R).

Padlyak B., Szarska S., Jungner H.

Optica Applicata

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2000

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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.