S. Raghavan et al., DETERMINATION OF THE THERMODYNAMIC ACTIVITIES IN (XCAO-X)CDO)(S,SLN) FROM A SOLID-ELECTROLYTE GALVANIC CELL IN THE TEMPERATURE-RANGE 823-1303-K((1), Thermochimica acta, 228, 1993, pp. 291-296
The thermodynamic activities of CaO in the solid solutions which can e
xist in the system CaO-CdO were determined in the temperature range 82
3-1303 K by the high temperature solid electrolyte galvanic cell techn
ique with calcium fluoride as the solid electrolyte. The conventional
cell arrangement of sandwiching the electrolyte in direct contact with
the electrodes was not found to give stable reproducible EMF values a
t temperatures above 1123 K. For the higher temperatures a modified te
chnique has been introduced, which permits the establishment of an equ
ilibrium through the gas phase. In the temperature range of study, the
system was observed to show near ideal behaviour. The results are in
agreement with the near zero enthalpies of mixing reported in the lite
rature and also with the theroretical models available for predicting
the mixing enthalpies in such systems.