In this master's thesis I will address the design of two aluminum and one nickel-iron oxide core-shell nanoparticle reactors, as well as the selection of the chemical precursors' triethylaluminum (TEA), aluminum trichloride, nickel carbonyl, and iron pentacarbonyl. This research provides evidence for the generation of aluminum oxide passivated aluminum nanoparticles from TEA, the failure to completely dissociate aluminum trichloride, and the successful growth of iron oxide (shell) onto nickel (core) nanoparticles. Reactions and synthesis are carried out in gas phase allowing the use of specialized aerosol sampling and characterization techniques. In addition to studying the particle in situ, TEM and EDS measurements are preformed post collection. Motivation for this work is driven by the nanoparticle's enhanced performance when used in explosive and propellants.