Radiation-induced swelling and softening in magnesium aluminate spinel irradiated with high-flux Cu ions

Lee, C. G.; Omura, Takahito*; Takeda, Yoshihiko*; Matsuoka, Saburo*; Kishimoto, Naoki*

Magnesium aluminate spinel of single crystal was irradiated with 60 keV Cu at a dose rate up to 100 A/cm, to a total dose of 310 ions/cm, in order to study changes in hardness and step-height swelling by high-flux implantation. Hardness determined by nano-indentation measurements steeply decreased with implantation. There is a strong negative correlation between dose-rate dependences of the hardness and the step-height swelling: the former decreases as the latter increases. The Rutherford Backscattering Spectrometry (RBS)/channeling measurements showed that the spinel is not completely amorphized over the dose-rate range in this study, and the radiation-induced softening observed is not due to amorphization. Results of optical absorbance suggested that radiation-induced point defects and their clusters on the anion sublattices of the spinel played an important role in the radiation-induced swelling under high-flux ion implantation.