Structural and Optical Properties of TiO2 Nanoarray Films Prepared by Liquid Phase Deposition

In this thesis, highly ordered TiO2 nanotube array films were fabricated via liquid phase depostition (LPD) method, based on different anodized aluminum (AAO) templates. The surface morphology, structure and diffuse reflection spectrum were analyzed by XRD, SEM, UV diffuse reflection spectrum. The results show that the crystal structure of the TiO2 nano array was anatase after heat-treating at 400 °C. SEM photographs show that nanobube arrays have an average diamieter of 50~80nm, the surface morphology is flat, and the tublar structure is not violated after heat-treating. As the growth times increased, red-shift effect was abserved in diffuse reflection spectra. And the optical band gap is respectively 1.48ev, 1.70ev and 2.08ev as the growth time is 10mins, 20 mins and 30mins.

Blue emission of Ce3+ in lanthanide silicon oxynitride phosphors

Ce3+-activated lanthanide silicon oxynitride (La5Si3O12N, La4SiO7N2, LaSiO2N, and La3Si8O4N11) phosphors were prepared by firing the mixture of La2O3, Si3N4, SiO2, and CeO2 at 1500–1600 °C under a 0.5 MPa nitrogen atmosphere. Diffuse reflection spectrum, photoluminescence spectra, and temperature-dependent luminescence of these phosphors are presented in this work. A blue emission of Ce3+ in all lanthanide silicon oxynitrides was observed under ultraviolet irradiation, which is strongest in La3Si8O4N11:Ce3+. The concentration quenching and thermal quenching of the samples were discussed.