Synthesis of submicron‐sized silver azide by multi‐nozzle Spray Flash Synthesis

Submicron-sized powders of silver azide (AgN3) were prepared by Curtius' reaction between silver nitrate (AgNO3) and sodium azide (NaN3) in aqueous solutions by a new process: the Spray Flash Synthesis (SFS). The SFS process consists in spraying the two precursor solutions in a heated atomization chamber (130-190 degrees C), maintained under low vacuum (15-30 kPa). The reaction occurs in the droplets which have collided; the final size of particles is limited by the fast evaporation of water and the small amount of matter available in each droplet which can be considered as an individual micro-reactor. The mean particle sizes of silver azide synthesized by the SFS process range from 220 nm to 390 nm, which means that these particles are three times smaller than those obtained by the conventional precipitation method. Submicron-sized AgN3 powders can be initiated by a photographic flash.