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Published online by Cambridge University Press: 01 February 2011
64-keV Ni ion implantation was performed at room temperature up to a dose of 1×1017 cm-2 in α-Al2O3 single crystals. The charge states, structure and optical properties of metallic embedded Ni nanoparticles were studied by using X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and optical spectroscopy, respectively. XPS analysis showed that implanted Ni ions are mainly in charge state of metallic Ni0. Nanoparticles distributed from the surface to 30 nm below the surface were observed in a bright-field cross-sectional image. The size of nanoparticles ranges from 1 to 5 nm in diameter. A selected area electron diffraction (SAED) pattern shows Ni nanoparticles with lattice parameter a = 0.352 nm. A high-resolution electron microscopy (HREM) image indicated the Ni-implanted area had been entirely amorphized. A new broad absorption band centered at 400 nm appeared in the optical absorption spectrum of the as-implanted crystal, due to surface plasma resonance (SPR) of Ni nanoparticles.