The effect of oxygen pressure in the synthesis of SnO2 micro/nanocrystals through thermal evaporation of Sn powder was investigated. The thermal evaporation process was performed at 1000 oC for 1 hr under various oxygen pressures. The pressure of oxygen changed from 10 to 500 Torr. The morphology of SnO2 crystals changed drastically with oxygen pressure. SnO2 nanoparticles with an average diameter of 120 nm were formed at oxygen pressure lower than 10 Torr. SnO2 nanowires were grown under an oxygen pressure of 100 Torr. The nanowires have diameters in the range of 100 ~ 500 nm and lengths of several tens of micrometers. As increasing the oxygen pressure to 500 Torr, the sizes of wires increased. A strong visible emission peak centered at about 500 ~ 600 nm was observed in the room temperature cathodoluminescence spectra of all the products.

Keywords: Tin powder, Thermal evaporation, Tin oxide, Micro/nanocrystals, Morphological change, Oxygen pressure.