Structural and electronic effects of helium interstitials in Y sub(2)Ti sub(2)O sub(7): A first-principles study

Results describing the interaction of helium with the Y sub(2)Ti sub(2)O sub(7) structure are presented. Density functional theory has been used to determine the solution energy of a variety of interstitial sites in Y sub(2)Ti sub(2)O sub(7), as well as to explain the effects of helium on the electronic structure. A large effect due to electron-electron repulsion is observed between the oxygen and helium electrons and an overall change in the bonding nature of atoms in the immediate vicinity is noticed when helium interstitials are present. This is a preliminary study to understanding the mechanisms causing complex oxide nanoclusters to serve as trapping sites for helium in nanostructured ferritic alloys.