Ion implantation and thermal annealing of α-Al2O3 single crystals

Abstract

The effects of ion implantation and post‐implantation thermal annealing of α‐Al₂O₃ have been characterized using ion scattering‐channeling techniques, and correlated with electron paramagnetic resonance (EPR) and microhardness measurements. Although most of the work was done on ⁵²Cr implanted specimens, preliminary results have been obtained also for implanted ⁹⁰Zr and ⁴⁸Ti. For Cr implantation, the Al₂O₃ lattice damage saturates at relatively low doses, but the near‐surface region never becomes amorphous. A preferential annealing behavior begins in the Al sublattice after ∼800 °C annealing, and in the oxygen sublattice, only after 1000 °C annealing. Lattice location measurements show that after annealing to 1500 °C, Cr is greater than 95% substitutional in the Al sublattice. Above 1500 °C, implanted Cr atoms redistribute by substitutional diffusion processes. EPR measurements show that part, if not all, of the implanted Cr is trivalent and substitutional after annealing to 1600 °C. Microhardness measurements are consistent with alloy formation in the process of ion implantation followed by thermal annealing.