Electrochemical determination of the activity of Na2O in the pyrochlore phase of the Sb2O4-NaSbO3 system

Abstract

Activity of Na2O in the pyrochlore phase of the system Sb2O4-NaSbO3 has been measured as a function of temperature in the range 1073–1412 K by electromotive force (emf) measurements of the following solid-state electrochemical cells. The solid electrolyte used in the above electrochemical cells is Na-ß-Al2O3, which is an excellent sodium-ion conductor in the temperature range of the measurements. From the measured reversible emf, the activity of Na2O in the Sb2O4-NaSbO3 system has been calculated. The temperature dependence of the logarithm of the activity of Na2O in various two-phase regions of the Sb2O4-NaSbO3 system can be represented as No thermodynamic data have been reported earlier in the literature for the system Sb2O4-NaSbO3, and the present data constitute the first thermodynamic information.