Papers by Keyword: Film Growth

Abstract: Ni-14wt%W model-alloy has been used to study the kinetics and the mechanism of high temperature internal oxidation in presence of an external oxide scale. Oxidations have been done in air at 1000°C for different oxidation times and have allowed the evaluation of the oxidation kinetic from mass gain and from oxide thickness measurements. The oxidation kinetic which follows a parabolic oxidation rate indicates a diffusive behaviour of species during the oxide formation. Cross-section observations by Scanning Electron Microscopy (SEM) and analysis by Grazing Incidence X-Rays Diffraction (GIXRD) show a multi-layered structure of the oxide. Starting from the surface towards the bulk alloy, the scale is layered as follows : (i) a pure nickel oxide (NiO) in the outer part (ii) a porous NiO matrix containing NiWO₄ second phase and (iii) an internal oxidation zone of tungsten, first forming WO₃ sub-micrometer oxides that progressively transform into NiWO₄ oxide precipitates in the alloy.

Abstract: In order to study the evolution of Ti-Si-N film growth, the total energies and absorption energies of the Ti-Si-N islands on TiN(001) surface and the activation energy of the configuration evolution have been calculated with the first principle method. Four configurations of Si-2Ti-2N island have been studied, which are a silicon atom in a 2Ti2N island (Si-in-2Ti2N), a silicon atom by a 2Ti2N island (Si-by-2Ti2N), a titanium atom by a 2N1Ti1Si island (Ti-by-2N1Ti1Si), and a nitrogen atom by a 2Ti1N1Si island (N-by-2Ti1N1Si), respectively. The investigation presents some results. In the growth process of Ti-Si-N film, (1) the Ti and N atoms bonding together to form islands and Si atoms staying outside of TiN islands will lead to the most stable configuration; (2) the Si atom tends to separate from TiN phase, but the configuration evolution is not very easy, the activation energy of the transition from Ti-by-2N1Ti1Si to Si-2Ti2N is about 1.94eV; (3) it shows a tendency for Si atoms to bond with N atoms, rather than with Ti atoms.

Abstract: Based on the Monte Carlo (MC) simulation, the film growth and magnetic properties of Ni (100) films are investigated. The simulated results indicate that the surface roughness of the Ni films drops with the increase of the substrate temperature and the decrease of the deposition rate. The Curie temperature Tc is greatly influenced by the surface roughness and size of Ni films. Moreover, it is found that the Curie temperatures of the films are related to the mean coordination number Z and the surface roughness r. The simulated results explain the experimental facts well.