The Fabrication Of Nanomaterials Containing Of Titanium And The Study On The Photoluminesce Properties

Nanomaterials have many applications in many fields, such as semi-conductor, photoluminescence, chemical industry and sensor et al., due to its special properties caused by the size effect. Among many kinds of nanomaterials, CaTiO₃ and TiO₂ as the typical representative of the nanomaterials containing of titanium have attracted much attention. In this thesis, we have successfully fabricated the CaTiO₃ nanomaterials and TiO₂ nanotube. The structure and the size of these nanomaterials can be tuned up by changing the experiment parameters. In addition, we also researched the properties of these materials. We expect to enhance the photoelectric and photocatalysis performance by using these materials containing of titanium. Three sections are mainly included as following:(1) Fabrication of Eu doping CaTiO₃ nanopowders and their photoluminescent propertiesIn this section, Eu3+-doped CaTiO₃ (CTO) nanoparticles were prepared by a sol-gel method. Three different charge compensation mechanisms were realized by substituting Eu ion at different sites. (i) Ca site substitution with Ca vacancy compensation (CTO-A); (ii) Ti site substitution with O vacancy compensation (CTO-B); (iii) simultaneous substitution at both Ca and Ti sites with self-compensation (CTO-AB). Strongly related to the site substitution, the photoluminescent (PL) intensities were increasing in the sequence of CTO-B>CTO-AB>CTO-A. The absorbance spectra analysis of pure CTO nanoparticles showed absorption in the UV light region, while the absorption of Eu doped CTO samples exhibited the blue shift owing to the presence of Eu3+. Moreover, the photocatalytic activities of samples for decomposing dyes were reverse to the sequence of PL intensities. The PL properties and photocatalytic activity of the Eu3+-doped CTO nanoparticles were thus discussed in detail from the viewpoints of the microstructures and charge transfer-related processes.(2) Fabrication of TiO₂ nanotubes and their photoelectric propertiesIn this section, we applied the anodic oxidation method to fabricate the TiO₂ nanotube structure, which the structure parameters could be controlled. From the pictures of scanning electronic microscope (SEM), we can obtain that the sample surface covered a layer of nanowire after anodic oxidation. Under the TiO₂ nanowire, the uniform, dense and highly ordered TiO₂ nanotube could be found. In additional, a layer of nanoring covered on the nanotube could be obtained after twice corrosion process, which formed a ring and tube heterostructure. For these two kinds samples, it is important that the structure parameters, such as the length of the nanotube and the size of the tube wall or nanoring et al., could be modulated by controlling the experiment parameters. We also discussed the photoelectric properties of the TiO₂ nanotube. It is found that the IPCE of TiO₂ nanotube reached near 9%. The I-T curve showed the current density is about 0.45×10^-2mA/cm² under light irradiation, and became 0 after turn off the light. Sample showed good photoelectric properties.(3) Fabrication of CaTiO₃ nanostructures based on the TiO₂ nanotubesWe prepared morphology-controllable CaTiO₃ nanostructure by hydrothermal synthesis (a most commonly used low temperature synthesis method) bases on TiO₂ nanotube. It is found that TiO₂ nanotube with anatase phase became CaTiO₃ nanostructure with orthorthombic phase under the influence of KOH. In additional, the morphologies of CaTiO₃ nanostructure could be controlled by modulating the amount of KOH. The sample surface formed an highly ordered and branch-similarly CaTiO₃ nanostructure while CaCl2 completely reacted with KOH. Through SEM it is also see many small particles stack up to form the film, and kept the order of the radial direction. Orderly structure on the sample surface may cause by capillary effect of nanotube. As the amount of KOH increased continually, highly density CaTiO₃ film formed.