Compositional dependence of redox equilibria in sodium silicate glasses
| Autor: | Alexander B. Morgan, Brian K. Kochanowski, Charlotte W. Schreiber, Henry D. Schreiber, Teresa G. Dunlap, M Todd Coolbaugh |
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| Rok vydání: | 1994 |
| Předmět: |
Coordination number
Inorganic chemistry chemistry.chemical_element Manganese Condensed Matter Physics Copper Redox Silicate Electronic Optical and Magnetic Materials chemistry.chemical_compound Cerium chemistry Mineral redox buffer Materials Chemistry Ceramics and Composites Qualitative inorganic analysis |
| Zdroj: | Journal of Non-Crystalline Solids. 177:340-346 |
| ISSN: | 0022-3093 |
| DOI: | 10.1016/0022-3093(94)90548-7 |
| Popis: | The effects of melt composition on the redox equilibria of cerium, chromium, copper, iron manganese and uranium have been individually determined in sodium silicate glass melts at constant oxygen fugacity and temperature. Increased melt basicity shifts the Ce4+Ce3+, Cr6+Cr3+, Mn3+Mn2+ and U6+U5+ redox couples in the direction of the oxidized state, and shifts the Cu2+Cu+ couple to the formation of the reduced state. The compositional shift is dependent on the solvation of the individual redox ions, in particular whether the oxidized or reduced state has the higher coordination number in the resulting glass. The Fe3+Fe2+ redox couple becomes more reduced as the melt composition becomes more basic up to a molar Na/Si ratio of about unity, but then becomes more oxidized as the melt is made even more basic. This compositional dependence is consistent with a change in coordination of Fe3+ with composition; in acid melts, the Fe3+ ion is in octahedral coordination, whereas in basic melts it changes to the FeO2− ion in tetrahedral coordination. |
| Databáze: | OpenAIRE |
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