Reduction of dopant ions and enhancement of magnetic properties by UV irradiation in Ce-doped TiO.

We report the experimental observation of and theoretical explanation for the reduction of dopant ions and enhancement of magnetic properties in Ce-doped TiO diluted magnetic semiconductors from UV-light irradiation. Substantial increase in Ce concentration and creation of oxygen vacancy defects in the sample due to UV-light irradiation was observed by X-ray and optical methods. Magnetic measurements demonstrate a combination of paramagnetism and ferromagnetism up to room temperatures in all samples.

Enhancement of catalytic activity by UV-light irradiation in CeO nanocrystals.

Ultraviolet (UV) light irradiation on CeO nanocrystals catalysts has been observed to largely increase the material's catalytic activity and reactive surface area. As revealed by x-ray absorption near edge structure (XANES) analysis, the concentration of subvalent Ce ions in the irradiated ceria samples progressively increases with the UV-light exposure time. The increase of Ce concentration as a result of UV irradiation was also confirmed by the UV-vis diffuse reflectance and photoluminescence spectra that indicate substantially increased concentration of oxygen vacancy defects in irradiated samples.

Defect engineering by synchrotron radiation X-rays in CeO nanocrystals.

This work reports an unconventional defect engineering approach using synchrotron-radiation-based X-rays on ceria nanocrystal catalysts of particle sizes 4.4-10.6 nm.