Anhydrous and Hydrated Barium Azide

Barium azide differs from the other azides discussed in this section in at least two reported respects It is a large band gap azide (see Chapter 5) and deflagrates but does not sustain steady state detonation [182]. Slow decomposition, due to both irradiation and heat, has been investigated extensively with the primary emphasis placed on gas-evolution studies. In this subsection the emphasis is on the disorder remaining in the sample after partial decomposition, primarily by 

In many of the studies it is assumed that the particles are nuclei of Ba metal, although barium nitrides are also found. Studies have been made of the rate of particle formation and the rate of particle growth during thermal decomposition [184,186]. The particles are initially round, but after a certain size is reached, they become diamond shaped [184,186]. The formation is structure sensitive. Torkar et al, reported that particle formation starts at the surface but that the particles or nuclei which are found are oblique pyramids, oriented relative to the crystal axes [187]. By X-ray diffraction and other techniques approximately 75% of thermally decomposed Ba(Na)2 has been identified as BaaN2 with the remaining 25% being Ba, presumably in metallic form. 

A few observations of the color of thermally decomposed samples have been reported and are of interest in comparing thermal- and irradiation-induced decomposition. Harvey reported no visible coloration of thermally decomposed 

Mott suggested that the decomposition process in Ba(N3)2 is similar to that in the silver halides [190], but this has been disputed on the basis of additional observations [191]. Mechanisms for photodecomposition are also discussed below. 

As noted, evidence has been reported for the formation of barium nitride as a result of thermal decomposition. X-rays have been reported to permanently color Ba(N3)2, and the results were interpreted in terms of nitride formation 

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