Surface blistering and void swelling of α-Al2O3 irradiated with H2+ ions followed by 1000, 1200 °C annealing

Abstract

Surface morphology and defect structures in α-Αl2O3 irradiated with 106 keV H2+ and post-irradiation-annealed at 1000, 1200 °C were investigated. The ion irradiations and annealing cause modifications to the Raman scattering peaks such as the peak disappearance and peak shifts. Surface blisters with several micrometers in diameter are visible. The mean blister sizes increase with increasing annealing temperatures and decrease with increasing irradiation fluences. Transmission electron microscopy characterizations reveal large numbers of spherical or oval shaped voids around the peak-damage zone. Faceted voids are also observed. The irradiation-induced dislocation loops are mostly annealed out with only some dislocation lines left inside. Nevertheless, small dislocation loops with sizes of ∼20–30 nm are characterized under different diffraction conditions, which are found to be associated with the void structures in the 1.5 × 1017 H2+/cm2 irradiated and annealed sample. These loop structures are considered to be induced through the ‘loop punching’ mechanism due to a high gas pressure inside during the bubble growth period.