title: Stability of Ni in nitinol oxide surfaces.
abstract: The stability of Ni in titanium oxide surface layers on nitinol wires known to release certain amounts of Ni was investigated by first principles density functional theory and transmission electron microscopy. The oxides were identified as a combination of TiO and TiO(2) depending on the thickness of the layer. The calculations indicate that free Ni atoms can exist in TiO at ambient temperature while Ni particles form in TiO(2), which was confirmed by the transmission electron microscopy observations. The results are discussed with respect to surface stability and Ni release due to free Ni atoms and Ni particles.
authors.affiliation: EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
authors.forename: He
authors.initials: H
authors.lastname: Tian
authors.forename: Dominique
authors.initials: D
authors.lastname: Schryvers
authors.forename: Di
authors.initials: D
authors.lastname: Liu
authors.forename: Qing
authors.initials: Q
authors.lastname: Jiang
authors.forename: Jan
authors.initials: J
authors.lastname: Van Humbeeck
mesh_terms: D000497:Alloys / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D008956:Models, Chemical; D009532:Nickel / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry
chemical_list: D000497:Alloys; D010087:Oxides; C009495:titanium dioxide; C013616:nitinol; D009532:Nickel; D014025:Titanium