Preparation And Optical Properties Study Of Several Ⅵ-compound Nanomaterials

Size tunable solid SnO2(STO) and hollow SnO2(HTO) nanospheres wereprepared by a sacrificing template method. The peaks around390nm were observed inphotoluminescence (PL) spectra. Based on the results, the PL intensity exhibitsmorphology-dependence and size-dependence, and HTO structure displays betteroptical properties than STO structure. The degradation of Methyl Orange (MO) inaqueous solution is selected as a probe reaction to evaluate the catalytic activity ofnano-SnO2. The result shows that HTO structure presents stronger photocatalytic (PC)activity. According to the result of specific surface area testing, the improved PL andPC properties of HTO structure can be mainly explained by the surface effect inducedby large specific surface area. This work is meaningful for developing nanoma terialswith enhanced optical and photochemical properties.One-dimensional rare earth oxides and hydroxides are of importance in manyapplications due to their rich physicochemical properties. In this work, we synthesizedLn(OH)3(Ln=Eu, Nd, Dy) nanorods by a hydrothermal method with assistance ofn-butylamine as an alkaline resource. The porous Ln2O3nanorods were producedthrough annealing the corresponding Ln(OH)3nanorods. XRD and TEM techniqueswere employed to characterize the products. The annealing process and the opticalproperties of as-synthesized Ln2O3are also investigated by TG and PL test. Weexpected that these nanomaterials could find potential applications in future.Eu-doped SnO2nanospheres were fabricated by the sol–gel calcination process.The effect of Eu doping concentrations on the structure and photoluminescenceproperties of Eu-doped SnO2nanocrystalline powders was investigated. X-raydiffraction patterns and feld emission scanning electron microscope are employed toinvestigate the morphology and the structure of Eu-doped SnO2nanospheres. Thesamples display reddish-orange light and red light when excited at indirect and directexcitation, respectively. Meanwhile, PL spectra indicate that the quenchingconcentrations are different when the excitation wavelength alters. Based on theanalysis of the PL spectra, it is believed that Eu3+ions located at different sites in theSnO2host are selectively excited.We grew the very new material which is called Erbium Chloride Silicate in bothcore/shell Si/ECS and pure ECS forms. I demonstrated that as growth temperature increases Si core layer shrinks. The Er concentration for ECS is1.6x1022which is2-3orders of magnitude higher than other erbium doped or compound materials such aserbium oxide erbium silicate. The main emission peak is at1.53um which is veryimportant wavelength for optical communication and the lines from peak are verysharp and the intensity is high. As temperature increases, crystalline quality andoptical quality gets better. XRD peaks becomes stronger and narrower and emissionlines become very sharp and strong. Also it is very important that linewidth of the1.53um at77K is only0.8nm which is much narrower than its counterparts. Since itemits1.53um light, we can use this material for optical fiber communication becausethis wavelength is in the lowest loss window for fiber optics. We also use it to makeoptical amplifiers and waveguides. We can also use it to increase the Si solar cellefficiency because by utilizing up and down conversion process we can increase theefficiency.Dual gradient method (DGM) has been successfully demonstrated as a means togrow semiconductor alloys with composition controllably varied over a large range.This paper attempts for the first time to establish a theoretical model in order tounderstand the detailed mechanism of the DGM and to guide future experiments. Onthe basis of chemical reaction equilibrium, we attempt to establish a universal modelfor the DGM growth of alloy nanowires based on the vapor-liquid-solid mechanism,using the example of quaternary ZnxCd1-xSySe1-ynanowires growth. The theoreticalpredictions based on our model are in good agreement with experimental data. Ourtheoretical model can relate the bandgap (and the composition) of as-synthesizedquaternary alloy nanowires and the supersaturation of the involved vapor phases to thelocal gradients of compositions and growth temperature. Our model and theestablished relationship could be important for guiding the future growth experimentsof semiconductor alloy nanowires with widely tunable bandgaps or with preciselycontrolled alloy compositions.