Cupric oxide nanoparticles in SiO2 fabricated by copper-ion implantation combined with thermal oxidation

Cupric oxide (CuO) nanoparticles (NPs) are fabricated in silica glasses (SiO2) by Cu-ion implantation and following thermal oxidation. First, Cu metal NPs were formed in SiO2 by the implantation of Cu negative ions of 60 keV to ∼6×1016ions∕cm2, and then the Cu NPs were oxidized to CuO NPs by annealing at 400–1000 °C in oxygen-gas flow. After the oxidation at 600 °C for 1 h, the surface plasmon resonance peak of metallic Cu NPs disappears. Grazing-incidence x-ray diffraction confirms the disappearance of Cu NPs and the formation of CuO NPs, but excludes the formation of Cu2O NPs which are thermodynamically less stable under atmospheric oxygen pressure. The CuO NPs show higher thermal stability up to ∼1000°C than Cu NPs.