Aero-Sol−Gel Synthesis of Nanoporous Iron-Oxide Particles: A Potential Oxidizer for Nanoenergetic Materials

Interest in developing an oxidizer matrix for reaction with nano-aluminum for energy-intensive applications involving explosives and propellants have led to the development of an aerosol-based sol−gel method (Aero-sol−gel) for preparing nanoporous iron-oxide nanoparticles with high internal surface area. We have employed sol−gel reactions in the aerosol phase using an iron(III) salt with an epoxide in a volatile solvent (ethanol), to generate nanoporous oxidizer nanoparticles. Porosity of the particles results from the nature of the sol−gel chemistry implemented. Energy-dispersive spectrometry (EDS) results indicate that the aerosol-based chemistry is qualitatively similar to that occurring in bulk sol−gel synthesis. The oxidizer particles obtained from the aero-sol−gel experiment are in the 100−250-nm size range as evidenced by SEM and differential mobility analysis (DMA). Porosity of particles is observed qualitatively in the TEM micrographs and quantitatively determined with BET surface area measurements which indicate that these particles have total surface area that is enhanced by a factor of 200 over the geometric surface area. The aero-sol−gel derived iron oxide has also been mixed with nano-aluminum and preliminary ignition tests have been performed to show the effectiveness of the oxidizer particles.