Microwave Synthesis and Optical Absorption Studies of SnO Nanocrystallites

Here, we report single phase pure SnO nanoparticles synthesized by microwave heating in aqueous media, using SnCl2.2H2O and HCl in presence of ammonia. The powders of SnO nanocrystallites with crystallite sizes less than 10 nm have been prepared by a solution process. It is noticed that amorphous precipitate of Sn+2 is crystallized with microwave heating. The SnO samples show excitonic peaks in UV-Vis absorbance spectra which is absent in the SnO bulk sample. Blue shift up to ~288 nm corresponding to an energy gap of 4.3 eV is observed for particle size of ~7 nm. The appearance of these excitonic peaks for nanocrystallites SnO may be attributed to the conversion of band gap from indirect in bulk SnO to the direct band gap in nanocrystallines SnO. The products were characterized by X-ray powder diffraction (XRD), and transmission electron microscopy (TEM).