Coordination and RedOx ratio of iron in sodium-silicate glassesстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 19 июля 2013 г.
Аннотация:Mössbauer and Electron paramagnetic resonance (EPR) spectroscopy studies of iron status in doped sodium-silicate glasses, (100-x)Na2O-(x)SiO2-yFe2O3 (x = 75;81 mol.%; y = 0.05-13 wt.%) were made as a function of glass matrix and total iron content . Mössbauer spectroscopy identified three signals: Fe3+ doublet, Fe2+ doublet and Fe3+ broad hyperfine splitting (HFS) at room temperature. HFS appeared even in the glass samples with total iron content about 7 wt.% and were explained by slow relaxation effect of ferric ions. X-band EPR spectra exhibited resonance signals at g 2.0, g 4.3 and a shoulder in the region of g 6. The distribution of ferric ions on different structural states was observed by EPR technique, as depending on total iron content. EPR spectra were computer simulated on the basis of rhombic spin-Hamiltonian with Zeeman and fine-structure terms. The nature of EPR absorption signals were interpreted as a combination of five types of Fe3+ complexes. Three of them were clustered iron ions and two others were isolated paramagnetic ferric ions in strongly distorted octahedral sites. The iron RedOx ratio (Fe2+/Fe3+) has been estimated by Mössbauer spectroscopy, while proportion of Fe3+ ions in adjacent sites (Fe3+(isolated)/Fe3+(clustered)) has been obtained from Mössbauer spectra and theoretically simulated EPR spectra. The results of both methods are in reasonable agreement for the glasses with y = 2.5, 4 and 7.