Fabrication And Yellow Luminescence Study Of Single-crystalline Sno₂ Nanostructure

In the past few years, great progress has been achieved in the synthesis, structural characterization, and physical properties investigation of nanostructures. Due to their peculiar characteristics and size effects, these materials often show some physical properties that are different from those of the bulk, and are of great interest both for fundamental studies and for potential applications. Among them, metal oxide such as SnO2 is a superexcellent example. SnO2 has been paid attention in a variety of applications in chemical, optical, electronic, and mechanical fields, because of its unique high conductivity, chemical stability, gas sensitivity, and semiconducting properties. Many syntheses of SnO2 with different morphologies, such as nanoscale belt, wire, and disk have been reported. However, there is a long way to go in the synthesis, structural characterization and applications investigation of SnO2. For instance, it is still in question that how the one-dimensional SnO2 emits luminescence and where the emitting position is. Based on the previous studies and the experimental conditions nowadays, we prepared SnO2 nanowires by Chemical Vapor Deposition (CVD) and SnO2 nanopowders by solvo-thermal method, and then do in-depth research in their nanostructure, growth mechanism, and luminescence mechanism.The high quality samples of SnO2 nanowires were fabricated by CVD. The samples were grown on the surface of silicon film coated by Au via a simple chemical reaction with SnO2 vapor, which was carried into the reaction region by high purity N2. We controlled the condition of normal pressure, low temperature, and detected the product by scanning electron microscopy (SEM), Raman spectroscopy (Raman spectra), X-ray diffraction (XRD), photoluminescence (PL). It is shown in the results: The SnO2 nanowires prepared in this method have a rutile structure and show excellent photoluminescence characteristics. The crystal growth directions is[101]. The nanowires have a good photoluminescence properties, luminescence peak at 540nm. First-principle Calculation (by VASP) indicates that the yellow luminescence derives from the Sn vacancy (VSn).Solvent-thermal method is in a critical condition, can occur under the normal conditions the reaction can not be achieved, and can generate metastable state structure of materials. In order to study the SnO2 nanostructure further, we prepare SnO2 nanopowders. In the preparation, SnCl4·5H2O, ethvlenediamine and oleic acid react by solvo-thermal method, and then the SnO2 nanopowders are obtained by centrifugal cleaning, drying, grinding and annealing the reaction products. XRD images for the nanopowders show that the grain size of the SnO2 nanostructure increases with temperature rising, and there is mixed-phase above the critical temperature. Therefore, it is important to determine a proper annealing temperature in the whole process.