Voltammetric studies in iron-doped 5Na(2)O center dot xMgO center dot(15-x) CaO center dot yAl(2)O(3) center dot (80-y) SiO2 melts

摘要

Melts with the basic compositions 5Na(2)O . xMgO . (15 - x)CaO . yAl(2)O(3) (80 - y)SiO2, doped with 0.25-0.5 mol% Fe2O3 were studied using square-wave voltammetry at temperatures in the range of 1300-1600degreesC. Decreasing the temperature resulted in more negative standard potentials. Introducing alumina in the soda-alkaline earth-silicate melts also resulted in less negative standard potentials, i.e. in a shift of the redox equilibrium to the reduced state. A further increase in the alumina concentration led to a re-decrease of the standard potentials. The alumina concentration attributed to maximum standard potentials is an effect of the CaO concentration. A structural model is proposed. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 24]