Effect of Ga on the Morphology of SnO2 Nano/Micro-Crystals Grown by a Thermal Evaporation Method

SnO2 nano/micro-crystals with different morphologies were fabricated by the thermal evaporation of SnO2 powders mixed with Ga2O3 powder. The synthesis process was performed at 1300oC in air. X-ray diffraction (XRD) analysis, energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were used to examine the morphology, microstructure, elemental composition and chemical property of the as-synthesized products. X-ray diffraction analysis revealed that the products were SnO2 with a tetragonal rutile crystal structure. From the Fourier transform infrared spectra of the products, Sn-O stretching mode was observed, which confirmed the formation of SnO2. Scanning electron microscopic analysis clearly showed that the morphology of the SnO2 crystals was significantly affected by the addition of Ga2O3 to SnO2 source powder. SnO2 crystals with a belt-like morphology were grown when the source powder without Ga2O3 powder was used. Rod-like SnO2 crystals were grown by using SnO2 powder mixed with Ga2O3 powder as the source powder. When the amount of Ga2O3 mixed in the source powder was increased, the morphology of the SnO2 crystals changed from rod to tube. Energy dispersive X-ray analysis indicated that the inner core of the tube-like crystals was composed of Snrich metastable phase. No catalytic particles were observed at the tips of the SnO2 nano/micro-crystals, suggesting that the growth process occurred by vapor-solid growth mechanism.