Thermodynamic properties of thiosamarates of calcium and barium and phases based on them

Effect of the nature of the alkaline-earth metal on the electrolytic and thermodynamic properties intrinsic to ternary thiosamarates of barium and calcium, which are capable of forming sulfide-conductive solid electrolytes, is considered. The thermodynamic property are examined by resorting to various modifications of the EMF method in concentration circuits with transfer. Dependence of the activity of binary CaS, BaS, and Sm₂S₃ in ternary MeSm₂S₄ on the composition of solid solutions is investigated with simultaneous determination of cationic and anionic transport numbers. The tendency of variations in the partial molar dissolution enthalpy (Delta bar H_{Sm_2 S_3 } ) in thiosamarates of alkaline-earth metals is studied as a function of the doping-additive content. The vacancy mechanism of the defect formation in the phases under investigation is confirmed. Thermodynamics of the formation of ternary BaSm₂S₄ out of binary sulfides is explored and (Delta H_{fBaSm_2 S_4 }^0 ) is determined for the first time ever.