MICROSTRUCTURAL CHARACTERIZATION OF ION-IMPLANTED POLYCRYSTALLINE ALUMINA

The microstructural changes induced in polycrystalline alpha-alumina b y high dose ion implantation were studied by Transmission Electron Mic roscopy (TEM) and X-ray Absorption Near-Edge Structure (XANES). Severa l regions were observed in the specimens prepared by the cross-section al method. We found that the implanted layer consists of a strongly da maged crystallographic structure, which tends to be destabilized in a cubic structure, where the atomic sites are very strained. The layer b eyond the distribution of implanted ions is characterized by a high de nsity of defects. A mechanism explaining the formation of this defecti ve layer is proposed.