Facile synthesis and luminescence properties of belt- and plate-like ZnO micro/nanocrystals via thermal evaporation of ZnO and Al mixture in atmospheric air

Zinc oxide (ZnO) micro/nanocrystals were grown via thermal evaporation of ZnO and Al powder mixture in air at atmospheric pressure. The effect of Al on the morphology and luminescence properties of ZnO crystals was investigated. The spherical shaped ZnO nanocrystals with the sizes of 150–230 nm were formed at 800°C. As the growth temperature increased from 800 to 900 and 1000°C, the morphology of ZnO micro/nanocrystals was changed to belt and plate shape, which indicated that the vertical growth of the crystals was suppressed with the growth temperature. The belt-like crystals had widths of 80–500 nm and lengths of several to several tens of micrometers. The plate-like crystals had widths ranging from 0.8 to 1.7 µm. X-ray diffraction patterns revealed that the ZnO had hexagonal wurtzite crystal structure. A strong ultraviolet emission centered at 380 nm was observed in the cathodoluminescence spectra of all the as-synthesized ZnO crystals.