Determining Extremely Low Sodium Activities at Elevated Temperatures: Problems and Perspectives

Abstract

The approach previously introduced in the literature in order to electrochemically determine extremely low sodium activities in Na–Me–O phase mixtures may sometimes be connected with difficulties arising from the evaluation of the experimental data. The data evaluation even becomes unrealistic if the phase mixture does not establish a univariant equilibrium. As an alternative, a new approach is proposed by means of which the establishment and maintenance of the phase equilibrium can be checked in situ, thereby providing an incomparably sensitive tool for differentiating between univariance and divariance of the phase equilibrium under consideration.