Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 28Citation - Scopus: 29Oxidation of Nanocrystalline Aluminum by Variable Charge Molecular Dynamics(Elsevier Ltd., 2010) Perron, A.; Garruchet, S.; Politano, O.; Aral, Gürcan; Vignal, V.We investigate the oxidation of nanocrystalline aluminum surfaces using molecular dynamics (MD) simulations with the variable charge model that allows charge dynamically transfer among atoms. The interaction potential between atoms is described by the electrostatic plus (Es+) potential model, which is composed of an embedded atom method potential and an electrostatic term. The simulations were performed from 300 to 750 K on polycrystalline samples with a mean grain size of 5 nanometers. We mainly focused on the effect of the temperature parameter on the oxidation kinetic. The results show that, beyond a first linear regime, the kinetics follows a direct logarithmic law (governed by diffusion process) and tends to a limiting value corresponding to a thickness of similar to 3 nm. We also characterized at 600 K the effects of an external applied strain on the microstructure and the chemical composition of oxide films formed at the surface. In particular, we obtained a partially crystalline oxide films for all temperatures and we noticed a strong correlation between the degree of crystallinity of the oxide film and the oxidation temperature. (C) 2009 Elsevier Ltd. All rights reserved.Article Citation - WoS: 1Citation - Scopus: 1Adsorption and Diffusion Characteristics of Lithium on Hydrogenated ?- and Ss-Silicene(Beilstein-Institut Zur Forderung der Chemischen Wissenschaften, 2017) İyikanat, Fadıl; Kandemir, Ali; Bacaksız, Cihan; Şahin, HasanUsing first-principles density functional theory calculations, we investigate adsorption properties and the diffusion mechanism of a Li atom on hydrogenated single-layer α- and β-silicene on a Ag(111) surface. It is found that a Li atom binds strongly on the surfaces of both α- and β-silicene, and it forms an ionic bond through the transfer of charge from the adsorbed atom to the surface. The binding energies of a Li atom on these surfaces are very similar. However, the diffusion barrier of a Li atom on H-α-Si is much higher than that on H-β-Si. The energy surface calculations show that a Li atom does not prefer to bind in the vicinity of the hydrogenated upper-Si atoms. Strong interaction between Li atoms and hydrogenated silicene phases and low diffusion barriers show that α- and β-silicene are promising platforms for Li-storage applications.Article Citation - WoS: 24Citation - Scopus: 29Thermal Stability of the High-N Solid-Solution Layer on Stainless Steel(Elsevier Ltd., 2002) Öztürk, Orhan; Williamson, Don L.Low-energy, high-flux N ion implantation into austenitic stainless steel held at approximately 400 °C results in dramatic improvements in the tribological properties due to sufficiently large N layer thicknesses and high-N-content solid solution phase. γN. In this paper, post-ion beam processing via isothermal annealing of a low-energy (0.7 keV), high-flux (2.5 mA/cm2) N implanted fee 304 stainless steel held at 400 °C has been investigated by Mössbauer spectroscopy and X-ray diffraction (XRD). Post-implantation annealing at 400 °C demonstrated the metastability and showed that the magnetic γN produced at lower ion energies and higher fluxes transformed systematically to a paramagnetic γN phase with less N content and less lattice expansion, thereby destabilizing the magnetic state of γN. The isothermal annealing results in much thicker γN layers but with less N in solid solution due to the N diffusion into the substrate. Based on the XRD data, the N diffusivity under isothermal annealing conditions is found to be D = 2X10-13 cm2/s at 400 °C, consistent with a model which explains that the trapping by Cr atoms in the stainless steel becomes more effective when N contents are low relative to the Cr concentration ( ~ 19 at.% in 304 stainless steel).