DECARBONATION CURVES AND ASSOCIATED THERMODYNAMIC DATA FOR SYNTHETIC CD-DOLOMITES CDMG(CO3)(2), CDMN(CO3)(2) AND CDZN(CO3)(2)

Decarbonation curve for the synthetic dolomite analogues; (Cd-dolomite s) were determined for CdMg(CO3)(2), CdMn(CO3))(2) and CdZn(CO3)(2) un der CO2 pressure of up to 2.5 kbar. All the three double carbonates we re completely disordered at the decomposition temperatures and hence t he thermodynamic data (Standard enthalpy; Delta H-f degrees, Standard free energy; Delta G(f) degrees) retrieved from the univariant decarbo nation curve corresponds to the disordered phases. They are: [GRAPHICS ] The mixing enthalpies and free energies for the formation of the dis ordered 1:1 solid solution phases are: [GRAPHICS] The thermodynamic da ta (Delta H-f degrees, Delta G(f) degrees and Delta H-r degrees, Delta G(r) degrees showed a positive correlation with the decomposition tem peratures. The mixing energies of the disordered double carbonates als o show a direct correlation with the cationic size differences.