Atomic collision and ionization effects in oxides

Irradiation with ions and electrons provides accelerated study of radiation damage in nuclear materials, such as those proposed for immobilization of actinides and long-lived fission products. The effects of ion irradiation in SrTiO3, Sm2Ti2O7 and Sr2Nd8(SiO4)(6)O-2, as representative materials, are studied using 1 MeV Au+ ions. The irradiation-induced disorder, due to atomic collisions processes, increases nonlinearly with irradiation dose and is well described by a disorder accumulation model that includes contributions from amorphous domains, point defects and defect clusters. Ionization from 200 keV electrons induces recrystallization at the amorphous/crystalline (a/c) interface that exhibits several distinct stages associated with residual defect annihilation near the interface, epitaxial regrowth at the interface and a surface-stabilized amorphous state. Understanding ionization effects and the coupled effects of electronic and atomic dynamics on material behavior is a challenging area for scientific research. (C) 2008 Elsevier B.V.. All rights reserved.