Copper and cobalt nanocolloids in implanted MgO crystals

Abstract

MgO single crystals were implanted with either Cu or Co-ions with energies of either 250 or 100keV. The defect profile induced by the implantation was primarily characterized by Rutherford backscattering spectrometry in the channeling mode and optical absorption measurements. Extinction bands, associated with Mie scattering from metallic colloids, were observed after the implantations. The behavior of the extinction bands during thermal annealings in flowing argon at increasing temperatures was investigated. At sufficiently high temperatures, most of the copper and cobalt ions diffuse out of the colloids and occupy substitutional sites in the MgO matrix.