2009 Volume 50 Issue 5 Pages 1148-1151
The distribution ratio of Se between Ag-Pb alloy and PbO phases was investigated at 1273 K. A chemical equilibrium technique was used for the measurement. The oxygen partial pressure was in equilibrium with both the phases, and it was measured by an EMF method. The distribution ratio, defined as the mole fraction of Se in PbO to the mole fraction of Se in metal, was plotted against the oxygen partial pressure. The distribution ratio decreased with an increase in the oxygen partial pressure. The slope of the plot indicates that Se dissolves in the PbO phase as oxide, which is unreasonable. The activity coefficient of Se in the Ag-Pb alloy was also measured, and it was found to decrease with an increase in the concentration of Ag. Se dissolved in the PbO phase in the non-oxide form. The activity coefficient of Se in Ag was estimated as 0.0009 at 1273 K.