Controlling the particle size of calcined SnO2 nanocrystals

Smaller SnO2 nanocrystals are prepared by a novel method. In this method, hydrous tin oxide nanoparticles are precipitated by dropping ammonium hydroxide into tin salt solution under sonication. Further calcination is conducted after the hydrous tin oxide nanoparticles are adsorbed onto the surface of SrCO3 nanoparticles. Calcination at 600 degreesC yields SnO2 particles with an average particle size of 3.5 nm. This compares with 5.9 nm for the sample prepared by the conventional method. The band gap of SnO2 nanocrystals increases from 3.65 eV with a particle size 5.9 nm to 3.97 eV with a particle size 3.5 nm.