Structural Investigation of Aluminum Nanoparticles as Energetic Materials

Understanding the agglomeration of aluminum (Al) nanoparticles during chemical synthesis and the changing properties after surface functionalization is the key to improvements of interfacial interactions and overall reactivity of Al particles as energetics. This work studies the effects of aluminum iodate hexahydrate (AIH) coating on changing the morphology and crystallinity of Al nanoparticles and their effects on coalescence during synthesis. Al particles with and without the AIH coating were investigated via transmission electron microscopy (TEM). Prior to the coating on Al, all particles consisted of crystalline cores surrounded by amorphous alumina (Al2O3) shell. The AIH-coated particles exhibited rough surfaces having the AIH coating as protruded nodules on Al particles, which would shrink and disappear in a few minutes. The coated particles also exhibited high crystallinity from the core to the outermost surface without the apparent presence of amorphous shell. The TEM diffraction pattern of the AIH-coated particles was consistent with a bulk Al crystal but with extra spots and relatively larger lattice spacings. The results suggest more severe agglomeration with a less compact structure for AIH-coated Al particles.