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Science Forum Index » Physics Forum » Influence of glass basicity on redox interactions of ...
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| ayaz... |
 Posted: Sun May 04, 2008 5:54 pm |
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Glass Physics and Chemistry
Volume 34, Number 1 / February, 2008
W. Thiemsorn1 , K. Keowkamnerd1, S. Phanichphant1, P. Suwannathada2
and H. Hessenkemper3
(1) Faculty of Science, Chiang Mai University, Chiang Mai, 50200,
Thailand
(2) Lambda Nu, Co. Ltd., 29/402 Chaengwattana Rd., Pakkret,
Nonthaburi, 11120, Thailand
(3) Institut für Keramik, Glas-und Baustofftechnik, TU Bergakademie
Freiberg, Leipziger Strasse 28, Freiberg, 09596, Germany
Received: 1 September 2006 Published online: 13 March 2008
Abstract The redox interactions of iron, manganese, and copper ion
pairs including absorption characteristics in a multicomponent soda-
lime-silica glass, were investigated. Glasses containing 11–19 mol %
Na2O were melted under an air atmosphere in an electric furnace at
1450°C for 8 h. The results of chemical analysis indicated that the
redox pairs of Fe2+/Fe3+, Mn2+/Mn3+, and Cu+/Cu2+ shift to more
oxidized states as a function of increasing glass basicity. The redox
interactions of individual pairs, e.g., Fe2+/Fe3+-Mn2+/Mn3+, Fe2+/Fe3+-
Cu+/Cu2+, and Mn2+/Mn3+-Cu+/Cu2+, were not strong but changed with
glass basicity. For the three redox pairs, Fe2+/Fe3+-Mn2+/Mn3+-Cu+/
Cu2+, both Mn3+ and Cu2+ ions simultaneously and proportionally
oxidized Fe2+ to Fe3+ and did not affect one another. The reaction
constants log Q 2 of Fe2+/Fe3+-Mn2+/Mn3+ and Mn2+/Mn3+-Cu+/Cu2+ redox
pairs decreased while the Fe2+/Fe3+-Cu+/Cu2+ and three redox pairs
systems changed markedly with increasing the glass basicity. The
oxidizing and reducing powers of each ion changed only slightly in the
present of one another, and the absorption spectra of all the single
polyvalent elements confirmed to the Lambert-Beer law. The spectra
depended directly on the concentrations of each absorbing ion. While
the spectra of glass doped with more than one element confirmed the
direction of the equilibrium shift, they were used only to predict the
degree of interaction. These investigations gave consistent results. |
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