The decomposition of cadmium carbonate in air and in vacuum

Cadmium carbonate powders were decomposed isothermally in air and in vacuum over the temperature range 563 to 773 K. The decomposition rates in vacuum were higher than those in air at corresponding temperatures. When decomposed in vacuum the carbonate phase experiences a total weight loss which is higher than that based on complete dissociation of CdCO₃. The excess weight loss is attributed to stoichiometric deviations and the evaporative dissociation of CdO. On the basis of first-order kinetics, the activation energies for the decomposition of the carbonate in vacuum and in air were calculated as 185 and 177 kJ mol^–1, respectively.