Question

What happens when barium azide is heated?

Answer 1

The thermal decomposition of un-irradiated azide and the effect of short-period pre-irradiation on this process has been studied. Nucleus formation is considered to be the production of F-centres which, by interaction with vacant anion sites, acquire mobility and so aggregate to form more stable double F-centres, or nuclei. Nuclear growth involves decomposition at the metal-salt interface, and the nitrogen produced diffuses out through the crystal. The activation energy for growth of small nuclei is shown to be higher than that for growth of nuclei of visible size; this concept requires the introduction of a slow growth correction, and the pressure of nitrogen expressed as a function of time of heating t is then given by a relation of the formula p = const. (t-y)6. The effects of pre-irradiation in promoting nucleus formation and the processes occurring in the ageing of freshly prepared azide are also discussed.