Abstract
SnO2 single crystals (columnar crystals and silver grass-like nanowhiskers) were synthesized by selective microwave heating of a TiO2-SnO2 mixture. The shape of the as-grown SnO2 crystals is strongly dependent on the atmosphere during microwave irradiation. This is due to the difference in growth mechanisms, as revealed by in-situ surface observation under microwave irradiation, in addition to scanning and transmission electron microscopy observations of irradiated specimens. In a N2 atmosphere, silver grass-like SnO2 nanowhiskers were obtained. On the other hand, columnar SnO2 crystals were obtained in air or an O2 atmosphere. Photoluminescence and absorption spectra of the as-grown SnO2 crystals were examined. Based on the analysis of a TiO2-SnO2 pellet, it was found that the bottom was selectively heated, and SnO2 sublimated by microwave irradiation. A density gradient texture of the sample pellet was formed.
