A Silver–Lead-Azide Core–Shell Nanoparticle for Novel Metal-Azide-Based Primary Explosives with High Stability and Enhanced Detonation Ability

Metal-azide-based primary explosives are the key charge in ammunition's energy sequence. For the weakness of weak detonation ability or ultrahigh sensitivity of metal azide (Pb(N₃)₂, LA; AgN₃, SA; Cu(N₃)₂, CA) and their composites, novel metal-azide-based primary explosives with characteristics of improved safety and detonation ability are urgently needed to meet ammunition's miniaturization development. In this work, a novel silver-lead-azide core-shell nanoparticle design, with SA as the core and LA as the shell, is realized by the microfluidic method. The silver-lead-azide core-shell nanocrystal shows fine particle size (average particle size distribution 0.06-0.19 μm), narrow particle size distribution (0.01-0.25 μm, 0.06-0.12 μm), improved thermal stability (decomposition temperature >325 °C), passivated electrostatic spark sensitivity, and adjustable activation energy. By controlling the LA-SA ratio, LA-SA (1-1) is characterized as the optimized silver-lead-azide core-shell nanocrystal, with characteristics of high decomposition temperature (351.34 °C), passivated electrostatic spark sensitivity (13.11 mJ, higher than that of LA 0.66 mJ), low ignition energy (33 μF capacitor-discharge, 50% trigger voltage 19.8 V, lower than the corresponding value of SA), and strong detonation ability. This work not only develops the controlled preparation method for the silver-lead-azide core-shell nanocrystal structure but also provides ideas for the design of novel primary explosives.