Effect of gamma irradiation on the thermal decomposition of zinc bromate by dynamic thermogravimetry

The thermal decomposition of γ-irradiated zinc bromate has been studied by dynamic thermogravimetry. THe reaction order, activation energy, frequency factor and entropy of activation were computed using the Coats-Redfern, Freeman-Caroll and Horowitz-Metzger methods and were compared with those of the unirradiated salt. Irradiation enhances the decomposition and the effect increases with the irradiation dose. The activation energy decreases on irradiation. The mechanism for the decomposition of unirradiated zinc bromate follows the Avrami model equation, 1-(1-α)1/3 = kt, and the rate-controlling process is a phase boundary reaction assuming spherical symmetry. (author) 21 refs.; 1 ref.; 3 tabs