Particle size distribution, lead azide decomposition

S. Kleinberg F.P. Stein, Effect of Particle-Size Distribution on the Thermal Decomposition of a-Lead Azide , JPhysChem 77, No 7, 870— 875 (1973) 13) Director, Explosives Re-... 

Hutchinson et al. [57] have examined the effects of particle size on the decomposition of lead azide powder. Finer powders (radius = 8 pm) decomposed more than twice as rapidly as coarser powders (radius = 24 pm). A mathematical model was developed which incorporated the independently measured particle-size distribution and gave an excellent description of the experimental sigmoid ar-time curves. 

An approach which circumvents the problem of the effect of particle-size distribution on decomposition kinetics was adopted by Walker et al [26] and by Fox [10], who worked with individual single crystals or collections of noninteracting particles of uniform size. A typical lead azide preparation of the latter type is shown in Figure 4. Walker et al found that sodium and thallous azides do indeed show induction periods which are dependent upon particle size the... 

The two studies, confined in detail to lead azide decomposition, suggest that closer attention to the effects of particle size distribution in experimental samples may reduce the difficulties of fitting the equations for nucleation and growth to experimental data. Nevertheless, curve fitting alone can never resolve such questions as at what sites does decomposition start in the crystal by what mechanism are azide ions converted to gaseous nitrogen and how do metal ions acquire electrons and grow as metal products ... 

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