THERMAL-DECOMPOSITION OF BARIUM AND STRONTIUM PEROXIDES

Isothermal TG studies of the thermal decompositions in nitrogen of barium (490-610 degrees C) and strontium (380-530 degrees C) peroxides to the corresponding oxides with the evolution of gaseous oxygen showed that reactions were deceleratory overall with an initial relatively rapid process followed by the main deceleratory reaction. Curves of fractional decomposition (alpha) against time could be described by the Ginstling-Brounshtein diffusion model (low alpha) and the first-order rate equation (BaO2, alpha > 3.0; SrO2, alpha > 0.5). The activation energy for the main deceleratory process of the decomposition of BaO2 is 185 +/- 5 kJ mol(-1), which is considerably higher than the value of 119 +/- 2 kJ mol(-1) for the deceleratory stage of the SrO2 decomposition. Non-isothermal kinetic analyses gave similar E(a) values for the decompositions of both BaO2 and SrO2, namely 165 +/- 5 kJ mol(-1). Possible mechanisms are discussed.