Generation of metal and metal oxide nanoparticles by liquid flame spray process

A liquid flame spray (LFS) process has been investigated for the generation of single component nanoparticles. In the LFS process, a solution consisting of metal nitrate dissolved in water is sprayed into a turbulent, high temperature H2-O2-flame. The primary spray droplets evaporate and subsequent reactions in the flame produce metal or metal oxide vapours which nucleate to final particulate form. In the study, the process characteristics were examined to produce 10–60 nm particles from silver, palladium and iron containing precursors. A systematic study using variable process parameters proved that the size of the generated nanoparticles is set by the mass flow rate of the metal precursor, only. The geometric standard deviation of the size distributions was seen to vary in a limited range of 1.35–1.4. The particle size was verified by aerosol instrumentation, the composition and morphology by X-ray diffraction (XRD) and transmission electron microscopy (TEM), correspondingly. The Ag and Pd particles were seen to consist of pure metals. For iron, the presence of all three of the following compounds were detected: Fe, Fe2O3 and Fe3O4.