γ-Irradiation effects on the non-isothermal decomposition of strontium nitrate by model-free and model-fitting methods

The kinetics of the thermal decomposition of untreated and γ-irradiated strontium nitrate, Sr(NO3)2 was studied under non-isothermal conditions at different heating rates (5, 10, 15 and 20 °C min−1) in nitrogen atmosphere. The data were analysed using both isoconversional and non-isoconversional methods. The activation energies were calculated by Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS) and Friedman (FR) methods. The results show that the irradiation enhances the decomposition and the effect increases with the irradiation dose. The activation energy decreases on irradiation. The appropriate conversion model for the thermal decomposition process selected by means of the master-plot method agrees with three-dimensional diffusion model (D3 mechanism), g(α)=[1−(1−α)1/3]2 for both untreated and irradiated salts at all heating rates.

► The thermal decomposition of Sr(NO3)2 occurs in a single step reaction.
► Irradiation enhances the thermal decomposition.
► Activation energy decreases on irradiation.
► The Master plot method reveals that D3 model best describes the kinetic process.