2018 年 126 巻 7 号 p. 547-550
The morphology of tin oxide (SnO2) crystals, which were formed by thermal evaporation of SnO2/graphite powder mixture, was changed with the ratio of graphite to SnO2 powder in the source material. The synthesis process was performed in air at atmospheric pressure and no catalysts and substrates were used, which makes the process very simple and low cost. At the low ratios of graphite to SnO2 powder in the source material, the SnO2 crystals had a spherical shape with nanometer dimensions. With increasing the ratio of graphite to SnO2 powder, the morphology of SnO2 crystals changed from particle to belt. The belt-shaped SnO2 crystals had the widths in the range of 1.2–3.1 µm and the lengths of several tens of micrometers. X-ray diffraction analysis showed that all the SnO2 crystals had a rutile tetragonal crystal structure. Visible emission band with the wavelength in the range of 400–600 nm was observed in the cathodoluminescence spectra of the SnO2 crystals.