Synthesis And Growth Mechanism Of One-Dimensional Nanostructures

As we all know,rare earth elements have unique electronic structures and large atomic radius,which makes rare earth materials have many physical and chemical properties that ordinary element materials do not have,so they are widely used in photoelectric converter,energy storage materials,high-efficiency catalysis,metallurgical engineering and other fields.In optical applications,semiconductor nanomaterials doped with rare earth elements show excellent properties in photoluminescence,up-down conversion luminescence and permanent magnet.They have been widely used in many fields,such as temperature sensing,photoluminescence energy storage functional materials,in vivo biological imaging,and military camouflage materials.In this paper,La2O3:Eu3+nanorods and Si:Er3+ nano wires have been investigated prepared by different methods,and the photoluminescence properties of the samples have been investigated.In addition,the growth mechanism of nanowires have been studied from a new theoretical perspective.The main result are listed as follows:1.La(OH)3:Eu3+rod-like nanostructures were successfully prepared by an improved hydrothermal method,and then annealed the nanoparticles into La2O3:Eu3+nanorods with porous morphology.XRD results show that the sample is pure hexagonal phase(P63/m),and the crystal quality is highly positively correlated with annealing temperature.In the emission spectrum test,the main emission peaks of the samples and their corresponding transitions are the 5D0?7F1 transition of Eu3+ion at 565 and 578 nm,the 5D0?7F2 transition of Eu3+ion at 604 and 611 nm,and the 5D0?7F3 transition of Eu3+ion at 654 and 663 nm.By comparing the emission spectra of the samples under different preparation conditions,it can be found that the luminescent properties of the samples show some correlation with annealing temperature and doping concentration.In addition,the excitation spectra of the samples were also studied.The results show that the emission of Eu3+ ions mainly is originated from the energy transfer of the charge transfer band supplied by the substrate materials.It shows that the as-synthesized La2O3:Eu3+ nanorods have great potential in the application of high efficiency fluorescent powder.2.Si:Er3+ nanowires were grown by chemical vapor deposition using ErCl3 powder and silicon as raw materials.The growth of Si:Er3+ nanowires at different growth temperatures and Au film thickness was discussed by morphology characterization.The result of XRD show that the half-peak width of the diffraction peaks become narrow with the increase of growth temperature,which indicates a strong positive correlation between the crystallization quality of nanowires and the growth temperature.The emission spectra of Si:Er3+ nanowires show that the emission peak of Si:Er3+ nanowires is mainly located around 1.53 ?m,and the emission intensity increases significantly with the increase of growth temperature,while the increase of Au film thickness can inhibit the emission intensity to some extent.Since the 1.53 ?m near-infrared light emitted by Si:Er3+nanowires is the wavelength with the lowest propagation loss in the fiber,this work is of great significance for the fabrication of optical amplifiers and optical waveguides used in optical fiber communication.3.The growth mechanism of vapor-liquid-solid was studied by Monte Carlo method from the point of probability statistics.In the paper,the morphology and distribution of the droplets on the substrate were simulated under different preparation parameters,and the probability of nanowire growth in angle and length were discussed.The results show that the better the uniformity of the droplet distribution on the substrate,the closer the growth angle of nanowires is to the vertical state.In addition,the length of nanowires is very sensitive to the thickness of the catalyst film,and for any fixed thickness of the film,And there are two nanowire lengths with high probability density.Our results provide a new perspective for the study of nanowire growth mechanism,and it is expected to provide theoretical basis for the growth and regulation of nanowires.