Thermodynamic Characterization of the Eutectic Phase Mixture NaNbO sub(3)-Na sub(3)NbO sub(4). II: Solid-State Electrochemical Investigation

The difference in the standard Gibbs-free energies of NaNbO sub(3) and Na sub(3)NbO sub(4) has been determined by means of two electrochemical approaches based on potentiometric solid oxide electrolyte galvanic cells. The results are consistent with each other and prove the phase equilibrium between the niobates to be univariant. Quantitatively, the data can be represented by (525-700C)[unconverted image]The results are in between a wide range spanned by estimated literature data and are close to the findings of a previous manometric study.