Production and stability of radiation-induced defects in MgAl₂O₄ under electronic excitation

This paper investigates the formation process of radiation-induced defects in magnesium aluminate spinel and their stability using transmission electron microscopy, with emphasis on the effects of electronic excitation. Small interstitial-type dislocation loops disappeared under electron-induced electronic excitation. The elimination rate of the loops was found to be one order higher than for α-alumina. The disappearance of dislocation loops by a dissociation mechanism into isolated interstitials is discussed through analysis of the growth-and-shrink process of the loops. HARECXS analysis on cross section specimens irradiated with 350 MeV Au ions has shown the progress of cation disordering along ion tracks to be a function of electronic stopping power, (dE/dx)_e. Cations were found to exchange their sites toward a random configuration. Such disordering appears from (dE/dx)_e = 10 keV/nm, and increases in size with increasing (dE/dx)_e to reach nearly 10 nm in diameter at 30 keV/nm, under an assumption of a fully disordered configuration.