Improving the understanding of radiation damage mechanisms at the nanoscale level is important for the development of advanced in-core sensors and robust oxide-based waste forms. In this study, a suite of atomic-scale experimental techniques, coupled with ab initio simulations, has been used to examine and characterize the evolution of radiation damage at the La2Ti2-xZrxO7 / SrTiO3 thin film heterojunctions after irradiation with 1 MeV Zr+ ions to simulate fission fragment damage. We probe the onset of amorphization at the nanoscale using aberration-corrected scanning transmission electron microscopy (STEM) and position-averaged convergent beam electron diffraction (PACBED), finding that the oxide interface exhibits markedly improved damage resistance, in contrast to the bulk of the film or substrate. A combination of energy-dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS) has been performed before and after irradiation to examine associated chemical and local electronic changes, and to identify the salient features mediating the interfacial enhanced damage response. Ab initio molecular dynamics simulations of bulk La2Ti2-xZrxO7 show that the accommodation of electronic-type damage (comprising half of the total damage energy of 1 MeV Zr+) can be related to the bandgap of the crystal, as well as the ability of the octahedral network to accommodate distortions. In addition, we present atomistic density functional theory calculations of the interface and discuss possible atomic-scale mechanisms for the observed radiation damage resistance. Our study indicates that the engineering of oxide interfaces may offer a means to tune both functional properties and damage resistance, with potential implications for device design in extreme environments.

Interfacial radiation damage resistance in oxide thin film heterojunctions: Atomic perspective

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.