Thermal evolution of precipitated phases in Au implanted MgO single crystal

MgO single crystals implanted with Au + ions (180 keV, 6 10 16 -10 17 ions cm −2 ) and annealed at temperatures between 25°C and 1100°C, have been analysed-by optical spectrophotometry-by Rutherford back-scattering (to confirm the effective presence and to study the distribution profile of Au atoms), and by TEM and X-ray diffraction (to identify the phases precipitated by thermal treatment). Thermal annealing between 550°C and 1100°C produced an optical absorption band located between 565 nm and 600 nm. This band can be attributed to a fee Au precipitate with diameter varying from 50 to 200 Å. Larger metallic colloids 1000 Å are in simple orientation with the matrix. Annealing at temperatures higher than 500°C produces a supplementary optical absorption located at 425 nm. This band can be attributed to Au plasma resonance. After annealing for 15 min at 1100°C, a new phase is detected by X-ray diffraction and TEM and identified as Au 3 Mg alloy with hexagonal structure.