Papers by Keyword: Yb-Doping

Abstract: The TiO₂ nanoparticles with different Yb doping amount were prepared by a facile sol-gel method. The samples were characterized by XRD, TEM, XPS, UV-Vis, and PL, etc. The influence of Yb-doping on structure and visible light photocatalytic activity of mixed phase TiO₂ was evaluated by photocatalytic degradation of methylene blue (MB) under the irradiation of fluorescent lamp. The results show that ytterbium appeared two kinds of Yb³⁺ and Yb²⁺ valence state on the surface of TiO₂. Ytterbium doping can restrain the phase transfer from anatase to rutile, prevent the grain growth, and increase the surface hydroxyl content. Appropriate amount of Yb doping and the proportions of rutile and anatase mixed phase can effectively inhibit the recombination of photogenerated electron and hole, expand the wavelength range of absorption spectrum, and improve the photocatalytic performance of TiO₂. Meanwhile, the photocatalytic activity of the Yb-TiO₂ samples was the best under the irradiation of fluorescent light when the sintered temperature T=500°C and n(Yb):n(Ti)=0.009, it was 95.2% within 6 h and significantly higher than 56.4% of pure TiO₂ under the same experimental conditions.

Abstract: Cathodoluminescence (CL) quenching was observed in ZnO nanostructures when doped with Yb by both chemical and physical methods. CL spectra of the samples revealed a defect emission at 2.25 eV in samples prepared by the chemical method, and an emission at 2.5 eV in samples prepared by the physical method. From the thermal treatment studies, it was found that oxygen vacancies are responsible for the 2.5 eV emission. Observed CL quenching in ZnO is explained through the participation of point defects in the energy transfer process from ZnO to Yb3+.