THERMODYNAMICS OF FORMATION OF HIGH CALCIUM ANTIMONITES FROM E.M.F MEASUREMENTS

The standard molar Gibbs energies of formation of the high calcium antimonites, namely, 2CaO.Sb2O3, 3CaO.Sb2O3 and 4CaO.Sb2O3 from the component oxides have been determined in the temperature range, 1193 to 1296 K by operating galvanic cells with calcium fluoride as solid electrolyte. The Gibbs energy of formation of 4CaO.Sb2O3(s) from the free oxides obtained in the present work at 1193 K is in reasonable agreement with that reported in the literature at 1101 K based on a CaO-stabilized zirconia solid electrolyte study.