In Flame Spray Pyrolysis (FSP), called also liquid flame spray (LFS), a precursor containing a salt of a desired compound is dissolved in a combustible solvent such as ethanol and is sprayed and ignited to form a burning spray flame. The heat generated by the combustion of the fuel and the precursor results in complete evaporation and burning of the solvent and the solid content of the precursor [26]. FSP has high potential for synthesis of composite nanoparticles that can be used as catalysts, sensors and electroceramics.
Typical products synthesized by FSP are TiO2 [27], Al2O3 [28], MgAl2O4 [29], Fe2O3 [30], etc. Multicomponent oxide powders, such as beta-SrMnO3 and NiMn2O4 [31], superconductors [32], and BaTiO3 [33] have been prepared by flame spray pyrolysis of solutions containing inorganic precursors. Production of composite mixed-metal oxide powders with rates up to 250 g/h has been reported [34, 35]. A typical set-up for nanoparticle synthesis by flame spray pyrolysis consists of a spray nozzle, a heat source for initial droplet evaporation and ignition, and an oxidant such as oxygen or air to facilitate combustion.
The nozzle feed rate and spray characteristics, flow rate and type of the oxidant, precursor combustion enthalpy and precursor water content are the parameters that control the temperature and gas phase
reactions of the precursor followed by subsequent particle growth and sintering, taking place within and after the spray flame. The product powder is usually collected by filtration. Micron-sized liquid droplets can be generated, using various atomizers, such as gas-assisted atomizers, ultrasonic atomizers, etc. Controlled synthesis
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