Experimental study of celestite-barite solid solution

Solid solutions of the barite-celestite series were synthesized under hydro thermal conditions. Lattice parameters were determined for the synthesized samples. Relationships between the composition and lattice parameters were calculated. The method of high-temperature solution calorimetry in 2PbO . B 2O3 melt at 973 K provided the enthalpy of celestite formation, DeltaH(f, 2 98.15)(o) = -1458.3 +/- 4.0 kJ/mol and showed a negative departure of (Sr, Ba)SO4 solid solutions from ideality. The method of differential scanning c alorimetry allowed us to obtain the temperature dependence of natural celes tite heat capacity in the range 298.15-800 K: C-P(o) = 148.43 + 3.31 x 10(- 3)T - 29.89 x 105T(-2) (298.15-800 K) J/mol K.