Droplet evaporation on a substrate at the final stage of Low Pressure Spray Pyrolysis and the final morphology of nanoparticles

For lowered pressure conditions femtoliter droplets evaporation on metallic substrate is investigated by experimental and theoretical methods. Simulation results of the kinetics of droplet evaporation, which substantially used the pinning effect, are presented. It was shown that the evaporation time of a droplet with the height 5 μm is about 0.01 s. For evaporation on the substrate droplets of aqueous solution with nanoparticles inside it was predicted the formation of the core–shell structure of nanoparticles. Qualitative confirmation of this effect is obtained. For Low-Pressure Spray Pyrolysis of droplets of aqueous solution of salts, the core is a metal oxide and the shell is a deposited layer of the initial salt.