EXPERIMENTAL STUDY OF CELESTITE-BARITE SOLID SOLUTION

Abstract

Solid solutions of the barite-celestite series were synthesized under hydrothermal 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 · B2O3 melt at 973 K provided the enthalpy of celestite formation, ΔHof, 298.15 = -1458.3±4.0 kJ/mol and showed a negative departure of (Sr,Ba)SO4 solid solutions from ideality. The method of differential scanning calorimetry allowed us to obtain the temperature dependence of natural celestite heat capacity in the range 298.15-800 K: Cop = 148.43 + 3.31 × 10-3T-29.89 × 105T-2 (298.15-800 K) J/mol K.