CuO nanoparticles, Cu₂O/CuO and CuO/TiO₂ nanocomposites exhibit excellent photocatalyst properties toward the degradation of methyl-orange and potassium-dichromate under the visible light irradiation.

The chemical state of N in N-doped amorphous ${\mathrm{Ge}}_2{\mathrm{Sb}}_2{\mathrm{Te}}_5$ $\left(a\text{-}\mathrm{GST}\right)$ samples with $0–14.3\mathrm{N}\mathrm{at.}\%$ doping concentrations was investigated by high-resolution x-ray photoelectron spectroscopy (HRXPS) and Ge $K$ -edge x-ray absorption spectroscopy (XAS). HRXPS showed negligible change in the Te $4d$ and Sb $4d$ core-level spectra. In the Ge $3d$ core-level spectra, a Ge nitride $\left(\mathrm{Ge}{\mathrm{N}}_x\right)$ peak developed at the binding energy of $30.2\mathrm{eV}$ and increased in intensity as the N-doping concentration increased. Generation of $\mathrm{Ge}{\mathrm{N}}_x$ was confirmed by the Ge $K$ -edge absorption spectra. These results indicate that the N atoms bonded with the Ge atoms to form $\mathrm{Ge}{\mathrm{N}}_x$ , rather than bonding with the Te or Sb atoms. It has been suggested that the formation of Ge nitride results in increased resistance and phase-change temperature.

Amorphous ${\mathrm{Ge}}_2{\mathrm{Sb}}_2{\mathrm{Te}}_5$ $\left(a\text{-}\mathrm{GST}\right)$ film, $100\mathrm{nm}$ thick, was grown by cosputtering from GeTe and ${\mathrm{Sb}}_2{\mathrm{Te}}_3$ targets on a silicon wafer at room temperature. The native oxidized layer, which was formed in air and about $20\mathrm{nm}$ thick measured by secondary ion mass spectroscopy, was removed by ${\mathrm{Ne}}^{+}$ ion sputtering for $1\mathrm{h}$ with $0.6\mathrm{kV}$ beam energy. Core-level spectra of the Te $3d$ and $4d$ , Sb $3d$ and $4d$ , and Ge $3d$ of the oxygen-free $a\text{-}\mathrm{GST}$ were obtained by high-resolution x-ray photoelectron spectroscopy with synchrotron radiation and compared with those from Ge and GeTe. The analysis implies that the $a\text{-}\mathrm{GST}$ is composed on the base of chemical states of GeTe.

4f-occupation, Ce⁺³/Ce⁺⁴ ratio and grain-size effects in Zr- and Hf-substituted CeO₂ nanoparticles are investigated by NEAXFS and EXAFS.

Eu dopants in CeO₂ leads to advancement in electronic structure, photoluminescence and photocatalyst properties.