Grain size control of calcined SnO2 nanocrystals: Raman study and room temperature ethanol sensing properties.

SnO2 nanoparticles were prepared via a sol-gel method by heating the mixture of hydrous SnO2 nanoparticles and SiO2 nanospheres at 600 degrees C. The average particle size of the obtained SnO2 nanoparticles is 3.3 nm, smaller than that of the SnO2 nanoparticles ( 6.4 nm) prepared by calcining the pure hydrous SnO2 at 600 degrees C. The restricting effect of SiO2 on the growth of SnO2 nanoparticles was discussed by Raman spectra. A blue shift of A1g ) and B2g Raman modes in SnO2/SiO2 composite was observed, and it was considered to be a compressive stress effect. The obtained SnO2 nanoparticles with a size of about 3.3 nm exhibit enhanced ethanol response at room temperature, and their recovery time is much shorter than that of the SnO2 nanocrystals with a size of about 6.4 nm.