Electronic ionization induced atom migration in spinel MgAl2O4

We report direct spectroscopic evidence for atom migration during the initial stage of electron irradiation in spinel MgAl2O4. Time-dependent electron energy-loss spectroscopy of the Mg and Al L23 edges shows that both Mg and Al have a tendency to occupy the octahedral interstices under electron irradiation, along with a slight expansion of the Al–O bonding distance, but there is little change in the structural framework of oxygen. The process is irreversible at room temperature.