Thermodynamic Investigations of the NaI ‐ AgI System by the EMF Method Using Beta‐Alumina Solid Electrolyte

Abstract

This work was done in order to investigate the ion exchange reaction between and β″‐alumina and to develop a new technique for thermodynamic investigations by the EMF method using the β‐alumina solid electrolyte. The following galvanic cell was assembled, and the EMF measurements were carried out in the temperature range of 325–806 KThe cell was kept at 626 K for 43 days, and an ion exchange reaction between and β″‐alumina was allowed. The ion exchange reaction was confirmed by a change in the EMF. Electrodes were then shorted at 626 K through a resistor six times, and Na of a known quantity was transferred to the cathode. After each shorting, the cell's EMF was measured at various temperatures. was finally formed at the cathode after the cell shortings, and then the EMF agreed with that of the cell in which was used as the cathode. The ion exchange between Ag+ ion in the and Na+ ion in the β″‐alumina crucible proceeded smoothly by the retention of the cell at temperatures higher than 657 K. By conducting the experiment over a period of five months, equilibrium EMF's for the following two kinds of three‐phase coexistences above 657 K were obtained: (i) and (ii) .