Electron irradiation damage in oxides

Structural changes occurring at or near surfaces during irradiation in the electron microscope have been reported in a broad range of oxide systems, but only relatively recently have they been investigated primarily in terms of radiation damage. The present study seeks to categorize some recent results as well as results given in the literature by the type of structural modification observed in order to gain a better understanding of the damage mechanism, whether it be ballistic, electronic, or thermal in nature. A specific example is given comparing TiO₂, a material known to undergo surface ionization damage in the form of desorption induced by electronic transitions (or DIET), and NiO, a material whose DIET characteristics are not well established. Electron irradiation damage is found to depend not only on the nature of the system, for example the valency of the cationic species, but also on the crystal orientation and surface preparation. The behavior of these materials indicates a complex radiation damage scheme which cannot be explained solely by electronic, thermal or ballistic damage considerations.