Studies of the Na2O-Na2SO4 system

The behavior of Na2O-Na2SO4 melts at 920 C has been studied by four techniques: (1) chemical analysis of quenched melts, (2) manometric experiments in which the reversible uptake of O2 by the melts was observed, (3) potentiometric studies, using oxide ion specific zirconia electrodes, and (4) voltammetry, which detects the number of oxidizable species. In oxygen atmospheres all four studies are consistent with peroxide formation in the melt, although values of the peroxide/oxide ratio vary somewhat with method. At low O2 pressures (less than 0.1%), the potentiometric results are anomalous.