Controlling the Particle Size of Calcined SnO₂ Nanocrystals

Smaller SnO 2 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 SrCO 3 nanoparticles. Calcination at 600 °C yields SnO 2 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 SnO 2 nanocrystals increases from 3.65 eV with a particle size 5.9 nm to 3.97 eV with a particle size 3.5 nm.