Vapor-phase Synthesis, Characterization And Photoluminescence Properties Of Nano-oxide

One-dimensional (1D) nanomaterials such as carbon nanotubes (CNT) have become an important research subject in the field of nanoscience and nanotechnology. Among these materials, functional oxide semiconductor nanostructures can be used as fundamental ingredients of smart systems, because their physical and chemical properties can be tuned through adjusting cation valence state and anion deficiency. The new synthetic methods, the extension of novel nanostructures and materials systems, as well as the exploration of novel properties and applications of 1D nanomaterials have become the most interesting contents. In this paper, the point is to synthesize one dimensional oxide nanomaterials and research the photoluminescence properties. The main contents of this dissertation are summarized as follows:1. The synthesis of Sn-doped ZnO nanowires on ITO substrate and optical propertiesSingle crystalline Sn-doped ZnO nanowires were successfully synthesized on indium tin oxide coated glass (ITO) substrate by simple thermal evaporation approach without introducing any catalysts. The morphology and microstructure were determined by field emission scanning electron microscopy (FE-SEM), X-ray diffraction, high-resolution transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and photoluminescence spectroscopy (PL). The investigation confirmed that the products were of the wurtzite structure of ZnO. These doped nanowires have diameters in the range of 30 to 50nm and lengths of several tens of micrometers with growth direction along the c-axis of the crystal plane. Photoluminescence (PL) of these doped nanowires exhibits a weak UV emission peak at around 400 nm and the strong green emission peak at around 495 nm at room temperature, which may be induced by the Sn doping. We used a different doping strategy for ZnO nanowires, the dopants originate from substrate rather than from source stock.2. Synthesis and photoluminescence properties of SiOx nanowires Large-scale SiOx nanowires were successfully synthesized by the simple thermal evaporation method without the presence of catalyst. These namowires self-assembled two different namostructures. The growth process of the SiOx namowires is based on vapor-solid (VS) growth mechanism. Its morphology and microstructures were determined by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and photoluminescence spectroscopy. Studies indicate that the diameters of about 100 nm and 10nm, lengths ranging from several tens to several hundreds of micrometers. The room-temperature PL spectrum of our product shows three emission bands centering at about 368nm, 388nm and 400nm, respectively.3. Synthesis and characterization of hierarchical zinc germinate nanostructuresNovel hierarchical zinc germinate nanostructures have been successfully synthesized by the simple thermal evaporation method without the presence of catalyst at 1100℃. Its morphology and microstructures were characterized by field emission scanning electron microscopy, X-ray diffraction, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and photoluminescence spectroscopy. SEM shows that the synthesized product displays interesting firefly-like morphology, in which numerous secondary branches (ZnGeO3 nanowires) are grown randomly around the main stems (Zn2GeO4 microrods). TEM indicates that Zn2GeO4 micorods are 2-3μm in diameters and several tens of micrometers in length. However, ZnGeO3 nanowires have diameters of about 15nm and range from ten to several hundred micrometers in lengths with the growth direction of [113]. A broad emission band from 350 to 550 nm is obtained in the photoluminescence (PL) spectrum of these nanostructures at room temperature. There are three emission peaks : an UV emission peak at 395 nm,a strong green emission peak at 455 nm and a blue emission peak at 532 nm.