Formation, migration, and clustering energies of interstitial He in α-quartz and β-cristobalite

• Published in: Journal of nuclear materials Vol. 479; no. C; pp. 224 - 231
• Main Authors: Lin, Kan-Ju, Ding, Hepeng, Demkowicz, Michael J.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.10.2016; Elsevier
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2016.06.049

Precipitation of implanted helium (He) is detrimental to many nuclear materials. A solid in which implanted He does not precipitate, but rather remains in solution and diffuses readily is potentially of interest for applications requiring resistance to He-induced damage. We use density functional theory (DFT) calculations to examine He interstitial formation, migration, and clustering energies in two SiO2 polymorphs: α-quartz and β-cristobalite. Our findings show greater He solubility and mobility in the latter than in the former. This difference appears to be due primarily to the unlike atomic-level structures of α-quartz and β-cristobalite, rather than their differing densities. Our findings also suggest that He is unlikely to cluster in either material. The behavior of He in α-quartz and β-cristobalite, and similar forms of silica make them promising materials for further investigation for potential use in applications requiring resistance to He-induced damage. •Formation/migration/clustering energies for He interstitials in α-quartz and β-cristobalite have been computed using DFT.•β-cristobalite has lower He interstitial formation and migration energies than α-quartz.•He interstitials do not show a tendency to bind to each other in either α-quartz or β-cristobalite.•Different He behavior in α-quartz and β-cristobalite originates in atomic-level structure rather than in density.