Search for implantation-induced “re-solution” of Na precipitates in MgO via optical spectroscopy and in situ TEM

Abstract

It has previously been shown that high fluence Na implantation into MgO crystals followed by annealing leads to the formation of metallic Na precipitates. We have studied the effect of a subsequent low-fluence Na implantation on such precipitates, i.e., the effect of Na damage cascades whose size is comparable to that of the precipitates. Optical spectroscopy experiments and in situ transmission electron microscopy (TEM) experiments performed on-line with the Orsay ion implantor are both discussed. It is shown that simple ballistic ion beam mixing cannot account for the results. The latter indicate that damage-induced mixing at the host matrix-precipitate interface leads to drastic changes in the precipitate composition, presumably due to in-diffusion of oxygen (and possibly Mg) into the precipitate volume.