Silver azide Subject

Silver azide can be readily prepared by precipitation from aqueous solutions containing silver and azide ions. Recrystallization from aqueous ammonia affords colourless plates and needles. It was found to be potentially explosive and often detonated when subjected to shock.131... 

It should be mentioned that the samples were compressed to only 1.8 g/mk in military applications lead and silver azides are pressed to 3-3.5 g/ml. Whether or not the same trends would be observed at higher loading densities is subject to question. 

In an attempt to determine the mechanism of electrical initiation, Bowden and McLaren [38] conducted experiments with 1.0 X 0.5 X 0.5-mm silver azide crystals having an electrical resistance of about lO Q, When subjected to a constant electrical field (450 V/cm), tire current through the crystal increased with time, and after several minutes, when the current reached 150 pA, an explosion took place. 

Haissinsky and Walen [35] subjected nitrogen iodide to 5-MeV a-particles from a polonium source. The dryness of the sample and the intensity of the source decreased the time to explosion. The investigators stated that "the detonation of nitrogen iodide could be explained by a local heating of a grain of the powder." However, they thought this was an exceptional result because lead azide, silver azide, and diazo-zw-nitroaniline perchlorate did not detonate from 1 mCi of Po within 20 min. In lead azide a yellowing of the material occurred. 

The electron bombardment of explosives has been undertaken by various investigators in an effort to initiate or decompose the material under study. One of the early investigations was undertaken by Kallmann and Schrankler [30], who bombarded TNT, mercury fulminate, nitrocellulose, and to some extent, picrates and azides with 10-kV, 1-mA electrons in vacuo but were unable to produce explosions. However, when heavy ions of argon and mercury were used, initiations were achieved with several substances with each of the ions. Muraour [31 ] subjected lead azide and silver acetylide to 90 kV at 3 mA for 3 min and only achieved explosion with silver acetylide. Both explosives blackened upon electron irradiation. Muraour believed that the explosion was either a thermal effect or that, by chance, a sufficiently large number of molecules decomposed at one point to bring about complete decomposition. 

Radiation-induced decomposition of insulating solids has been the subject of extensive research for many years. Because of their structural simplicity, the alkali and silver halides have perhaps received the widest attention. Studies of radiation-induced decomposition in azides could represent the next logical step in structural complexity. The azides in many respects are similar to the halides. Like the alkali halides, the alkali azides are primarily ionically bonded with band gaps of the order of 8 eV. Like the halides, there are azides with smaller band gaps (less than 4 eV). Important differences between the halides and azides are the presence of the triatomic azide anion and the lattice symmetry differences, which are perhaps a result of the nonspherical charge distribution on the azide ion. The salient questions which arise for the purpose of this chapter when one compares the azides to the hahdes are How does the the presence of the molecular anion influence radiation-induced decomposition are new and/or different kinds of defects produced how does the azide molecular anion influence the defect production process ... 

---