Crack nucleation in ion beam irradiated magnesium oxide and sapphire crystals

Abstract

Monocrystals of magnesium oxide and sapphire have been subjected to ion implantation with 86 keV Si - ions to a dose of 5×10 16 cm -2 and with 3 MeV H + ions with a dose of 4.8×10 17 cm -2 prior to thermal stress testing in a pulsed plasma. Fracture and deformation characteristics of the surface layer were measured in ion implanted and unimplanted samples using optical and scanning electron microscopy. Ion implantation is shown to modify the near-surface structure of samples by introducing damage, which makes crack nucleation easier under the applied stress. The effect of ion dose on the thermal stress resistance is investigated and the critical doses which produce a noticeable change in the..