Ceramics-Silikáty 30, (4) 289 - 295 (1986)

On the basis of measuring the electrochemical voltage of the cell Fe(s) I Na₂O . 3 SiO -x FeO(l) I ZrO₂ (CaO) I Ni, NiO(s) I Mo(s) the activity of ferrous oxide was determined for x(FeO) = 0.005—0.06 at 1300—1400 °C. At temperatures of 1300—1350 °C, the FeO activity exhibits a negative deviation from Raoult´s law and at 1400 °C approaches the ideal behaviour. A linear relationship between EMF and log x (FeO) was found, the values of standard electromotive force E° and the number of exchanged electrons n were determined; the values are in agreement with theoretical assumptions. The results indicate that it is in principle possible to measure a(FeO) in commercial glass melts by means of the given arrangement.