The effect of crystal orientation on damage accumulation in chromium-implanted Al2O3

Chromium-implantation of single crystal aluminium oxide (Al2O3) has been shown to be anisotropic with respect to damage accumulation. Ultra-low load indentation and Rutherford Backscattering Spectroscopy (RBS) have been used to demonstrate the dependence of radiation damage on fluence and crystal orientation. Single crystal Al2O3 specimens of c-axis ([0001] normal to the surface) and a-axis ([1120] normal to the surface) orientations were ion-implanted simultaneously and found to possess different near-surface mechanical properties. Subsequent RBS-ion channeling examination indicated different amounts of disorder in both the aluminum and oxygen sublattices for the two orientations. These results imply a higher amorphization threshold in terms of implantation fluence for the a-axis oriented samples. 15 refs., 6 figs