Thermodynamic Characterization of the Eutectic Phase Mixture NaNbO3/Na3NbO4. I: Literature Survey

Abstract

The literature about the thermodynamic properties of NaNbO3 and Na3NbO4 has mainly been governed by estimations. The only exceptions are two current calorimetric investigations on the standard enthalpy of formation of NaNbO3 and, in addition, an old and inappropriately evaluated study on the carbon dioxide equilibrium gas pressure over the phase mixture NaNbO3/Na3NbO4/Na2CO3. Upon reevaluating the latter results, first experimentally proven data on the difference of the Gibbs‐free energies have been obtained (715°–822°C): image