Bonding and ion–ion interactions of Mn2+ ions in fluoride-phosphate and boro-silicate glasses probed by EPR and fluorescence spectroscopy
| Autor: | Efstratios I. Kamitsos, Doris Ehrt, Doris Möncke, Manfred Friedrich, Andreas Herrmann |
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| Rok vydání: | 2011 |
| Předmět: |
Chemistry
Metaphosphate Analytical chemistry Condensed Matter Physics Fluorescence Fluorescence spectroscopy Electronic Optical and Magnetic Materials Ion BORO law.invention chemistry.chemical_compound Covalent bond law Materials Chemistry Ceramics and Composites Physical chemistry Electron paramagnetic resonance Hyperfine structure |
| Zdroj: | Journal of Non-Crystalline Solids. 357:2542-2551 |
| ISSN: | 0022-3093 |
| DOI: | 10.1016/j.jnoncrysol.2011.02.017 |
| Popis: | Electron paramagnetic resonance (EPR) and fluorescence spectroscopy are sensitive and selective methods for probing coordination and bonding of Mn2+ ions in glasses. Both methods provide additional information on Mn–Mn ion interactions and cluster formation. Mn2+ was found to be tetrahedrally coordinated in boro-silicate glasses of high optical basicity, and octahedrally coordinated in low alkaline boro-silicate glasses (duran-type) as in fluoride-phosphate glasses. Broad emission bands and multicomponent fluorescence decay curves in duran glasses indicate very strong Mn–Mn ion interactions and the presence of multiple Mn2+ sites. Site distribution is more homogenous in metaphosphate glasses, though concentration quenching is apparent at high Mn-levels. As the Mn-content increases the EPR spectra show exchange narrowing due to a decrease in the Mn–Mn distances in the duran series, but show extreme linewidth broadening due to increased cluster sizes at constant Mn–Mn distances for metaphosphate glasses. For the fluoride-phosphate and boro-silicate systems investigated, fluorescence lifetimes are found to decrease as the wavelength of the emission maximum increases and with increasing g-values of the sextet at g = 2. For octahedral coordination of Mn2+ ions the EPR hyperfine splitting constant decreases linearly with increasing optical basicity, as a result of an increasing covalent character of the Mn2+–ligand bond. |
| Databáze: | OpenAIRE |
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