Mössbauer and optical spectroscopy of phosphoniobate and phosphotantalate glasses doped with iron
| Autor: | Marco Bettinelli, Adolfo Speghini, Umberto Russo, Barbara Lovisetto, Silvia Marson |
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| Rok vydání: | 2001 |
| Předmět: | |
| Zdroj: | Philosophical Magazine B. 81:313-320 |
| ISSN: | 1463-6417 1364-2812 |
| DOI: | 10.1080/13642810108221986 |
| Popis: | Glasses of the nominal compositions.xNb2TO5-(1 - x) (95mol% NaPO3-5% Na2B4O7) (x = 0, 10.3, 20.6, 30.0, 36.5 or 43.0) and x-Ta2O5-(1 - x) (95mol% NaP03-5mol%Na2B4O7) (x = 0, 5.0, 9.3 or 14.0) were prepared by conventional quenching of the melts. Raman spectroscopy shows that introduction of T2O5 (T = Ta or Nb) in smali amounts gives rise to the formation of ‘isolated’ TO6 octahedra. As the concentration of T2O5 increases, the spectra suggest the formation of corner-sharing TO6, octahedra and finally, for the glasses richest in T2O5, of a three-dimensional association of cornersharing, less distorted octahedra. All these considerations lead to the conclusions that both niobium and tantalum in octahedral coordination act as network formers strengthening the glass network. The near-infrared spectra have provided information on the coordination geometries of iron(II) that has been used for the interpretation of the Mossbauer spectra. In this way the simultaneous presence of iron(III) and iron(II) in ... |
| Databáze: | OpenAIRE |
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