6533b82efe1ef96bd1293c63
RESEARCH PRODUCT
Ab initio simulations of oxygen interaction with surfaces and interfaces in uranium mononitride
Eugene A. KotominYu. F. ZhukovskiiDmitry BocharovDenis Gryaznovsubject
Nuclear and High Energy PhysicsCondensed Matter - Materials ScienceAb initioMaterials Science (cond-mat.mtrl-sci)FOS: Physical scienceschemistry.chemical_elementOxygenGibbs free energyCrystallographysymbols.namesakeCondensed Matter::Materials ScienceAdsorptionNuclear Energy and EngineeringchemistryChemical physicsVacancy defectAtomsymbolsSupercell (crystal)Physics::Atomic and Molecular ClustersGeneral Materials ScienceGrain boundaryPhysics::Chemical Physicsdescription
Abstract The results of DFT supercell calculations of oxygen behavior upon the UN (0 0 1) and (1 1 0) surfaces as well as at the tilt grain boundary are presented. Oxygen adsorption, migration, incorporation into the surface N vacancies on (0 0 1) and (1 1 0) surfaces have been modeled using 2D slabs of different thicknesses and supercell sizes. The temperature dependences of the N vacancy formation energies and oxygen incorporation energies are calculated. We demonstrate that O atoms easily penetrate into UN surfaces and grain boundaries containing N vacancies, due to negative incorporation energies and a small energy barrier. The Gibbs free energies of N vacancy formation and O atom incorporation therein at the two densely-packed surfaces and tilt grain boundaries are compared. It has been also shown that the adsorbed oxygen atoms are highly mobile which, combined with easy incorporation into surface N vacancies, explains efficient (but unwanted) oxidation of UN surfaces. The atomistic mechanism of UN oxidation via possible formation of oxynitrides is discussed.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2012-11-24 |