Redox potentials of Fe
3+/Fe
2+ in silicate liquids measured by voltammetry were evaluated by comparison with those obtained by other analytical methods. Differential pulse voltammetry was carried out for 20Na
2O·80SiO
2 and 18K
2O·82SiO
2 (mol%) melts doped with 0.5 or 3 wt% Fe
2O
3 and 15Na
2O·9CaO·76SiO
2 and 25CaO·16MgO·9Al
2O
3·50SiO
2 melts doped with 1 wt% Fe
2O
3. Observed half wave potentials (
E1/2) agreed with those of previous voltammetry experiments, however, systematically smaller than
E1/2 calculated from redox ratios measured by wet chemistry and Mössbauer spectroscopy and redox potentials estimated from calorimetric data by about 0.1-0.3 V. The Fe
3+/Fe
2+ ratios calculated from the
E1/2 by the voltammetry were always overestimated compared with those by other analytical methods. We could not explain the reason for discrepancy of the
E1/2. It is expected that at least the discrepancy can not result from reduction of oxygen in working electrode, ohmic drop effect and difference between diffusivities of Fe
2+ and Fe
3+ in the liquids.
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