M. Parlinska-Wojtan

École Polytechnique Fédérale de Lausanne, Lausanne, VD, Switzerland

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Publications (8)6.92 Total impact

  • [show abstract] [hide abstract]
    ABSTRACT: Thin films of TM–X–N (TM stands for early transition metal and X = Si, Al, etc.) are used as protective coatings. The most investigated among the ternary composite systems is Ti–Si–N. The system Ti–Ge–N has been chosen to extend the knowledge about the formation of nanocomposite films. Ti–Ge–N thin films were deposited by reactive magnetron sputtering on Si and WC–Co substrates at Ts = 240 °C, from confocal Ti and Ge targets in mixed Ar/N2 atmosphere. The nitrogen partial pressure and the power on the Ti target were kept constant, while the power on the Ge target was varied in order to obtain various Ge concentrations in the films. No presence of Ge–N bonds was detected, while X-ray photoelectron spectroscopy measurements revealed the presence of Ti–Ge bonds. Transmission Electron Microscopy investigations have shown important changes induced by Ge addition in the morphology and structure of Ti–Ge–N films. Electron Energy-Loss Spectrometry study revealed a significant increase of Ge content at the grain boundaries. The segregation of Ge atoms to the TiN crystallite surface appears to be responsible for limitation of crystal growth and formation of a TiGey amorphous phase.
    Thin Solid Films 01/2006; 496(2):336-341. · 1.60 Impact Factor
  • C. S. Sandu, M. Benkahoul, M. Parlinska-Wojtan, R. Sanjinés, F. Lévy
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    ABSTRACT: Hexagonal β-Nb2N, cubic δ-NbN and hexagonal δ′-NbN films were deposited by reactive magnetron sputtering from a Nb metal target in Ar+N2 atmosphere at various nitrogen partial pressures. Structural and mechanical properties of these films were investigated by X-ray diffraction, Electron Probe Microanalysis, Transmission Electron Microscopy, Rutherford Backscattering Spectroscopy, residual stress and nanoindentation measurements. TEM studies reveal that the films have a columnar morphology. The hardness of the films depends on the film phase: the hardness reaches 35 GPa and 40 GPa for hexagonal β and δ′ phases, respectively, and 25 GPa for the cubic δ phase. The δ′ phase films show a compressive residual stress of about 3.5 GPa, whereas no residual stress can be measured in δ and β phase films. The relative density (compared with the bulk value) of films depends on the film phase: 0.8 for δ, 0.86 for δ′ and 0.96 for β. It is remarkable that the hardness of the hexagonal δ′ phase films is significantly higher than the hardness of the β phase films, in contrast with generally accepted morphological trends.
    Surface & Coatings Technology - SURF COAT TECH. 01/2006; 200(22):6544-6548.
  • R. Lamni, R. Sanjines, M. Parlinska-Wojtan, A. Karimi, F. Levy
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    ABSTRACT: Thin films of zirconium based ternary transition metal nitrides Zr1-xMxN with M=Al, Cr were deposited on silicon, and WC–Co substrates by reactive magnetron sputtering. The chemical composition was measured by electron probe microanalysis. Cross-section transmission electron microscopy together with x-ray diffraction analysis showed that the films were solid solution single-phase fcc NaCl type of structure (B1). The columnar morphology, examined by transmission electron microscopy, does not change with increasing aluminum and chromium content. The stress-free lattice parameter of both coatings decreases linearly with x. With the increase of the Al content, the texture of the fcc–Zr1-xAlxN thin films progressively changes into randomly orientated, whereas that of Zr1-xCrxN remains unchanged. The nanohardness values gradually increase from Hn=21 up to 28 GPa as x increases from 0 to 0.43: the maximum hardness corresponds to a valence electron concentration =8.57 for x=0.43. In contrast, the hardness and Young’s modulus in Zr1-xCrxN remain nearly the same for all Cr contents.
    Journal of Vacuum Science & Technology A Vacuum Surfaces and Films 01/2005; 23(4):593-598. · 1.43 Impact Factor
  • C. S. Sandu, R. Sanjinés, M. Benkahoul, M. Parlinska-Wojtan, F. Lévy
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    ABSTRACT: Ti–Ge–N single-layer and TiN/GeN-multilayer thin films were deposited by reactive magnetron sputtering on Si and WC–Co substrates at constant temperature Ts=240 °C, from confocal Ti and Ge targets in a mixed Ar/N2 atmosphere. The nitrogen partial pressure, the TiN deposition time tTi and the power on the Ti and Ge targets were kept constant. In order to obtain various GeN layer thicknesses in the films, the deposition time ratio tGe/tTi was varied. TiN/GeN multilayer films with TiN thickness ∼5 nm and various GeN thicknesses between 0.5 and 5 nm were deposited. A nanocrystalline multilayer film is formed, where the suppression of crystal growth is controlled by the successive deposition of two phases. TEM investigations revealed important changes induced by GeNx thickness variation: the columnar single-layer morphology switches into a multilayer morphology. The critical GeN thickness for changing the type of morphology is controlled by the diffusion of Ge atoms at the TiN crystallite boundaries. The morphology modification from single-layer to multilayer type determines the film hardening. Electron probe microanalyses (EPMA), scanning tunneling microscopy (STM), transmission electron microscopy (TEM), nanoindentation and X-ray diffraction (XRD) techniques were employed to characterize single- and multilayer films. The properties of alternate-deposited films are compared to those of co-deposited ones and interpreted.
    Surface & Coatings Technology - SURF COAT TECH. 01/2005; 200(5):1483-1488.
  • [show abstract] [hide abstract]
    ABSTRACT: Thin films of NbSiyNx have been deposited by reactive magnetron sputtering from confocal Nb and Si targets in mixed Ar/N2 atmosphere, at a substrate temperature of 250 °C. The total pressure, the nitrogen partial pressure and the current on the Nb target were kept constant, while the current on the Si target was varied in order to obtain Si concentrations between 1 and 34 at.%. For Si contents below 11 at.%, X-ray diffraction (XRD) reveals that the films are crystalline and have a fcc δ-NbN structure. For higher Si concentrations, the films exhibit a multiphase structure consisting of δ-NbN nanocrystallites and an amorphous matrix. The texture and the crystallite size depend on the Si content. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements allowed to identify the amorphous phase as Si3N4. Transmission electron microscopy (TEM) observations reveal that the microstructure of films is columnar, and that each column is formed by an agglomerate of crystallites. Amorphous regions were observed on the high-resolution transmission electron microscopy (HRTEM) images of the films with CSi=11 and 20 at.%.Nanoindentation measurements show that the hardness increases with increasing Si content up to 5 at.%, and reaches a maximum of 34 GPa. Above 11 at.% of Si, it decreases to the value comparable to that reported for amorphous Si3N4 (22 GPa). The hardness variation of the NbSiyNx films appears to be related to the formation of the amorphous Si3N4 phase and its volume fraction within the film. This behavior is similar to that observed in nc-MeN/a-Si3N4 nanocomposites (Me=Ti, W, V).
    Surface and Coatings Technology 01/2004; · 1.94 Impact Factor
  • M. Parlinska-Wojtan, A. Karimi, O. Coddet, T. Cselle, M. Morstein
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    ABSTRACT: Structure and stability of vacuum arc-deposited Ti1−xAlxSiyN hard coatings were studied before and after thermal treatment. Substituting titanium by aluminium and silicon results in a structure refinement in these multicomponent coatings through different mechanisms. Adding small amounts of Al+Si into TiN at first increases the hardness due to solid solution hardening. When the (Al+Si)/Ti atomic ratio reaches about 0.8, a phase separation into two cubic phases, Ti1−xAlxN and zinc-blende AlN, occurs and the nanohardness drops. At an even higher (Al+Si)/Ti ratio of 1.3, the hexagonal wurtzite-type AlN phase begins to be formed as well, while the hardness does not decrease any more. This AlN phase segregation may be promoted by the increasing thickness of (Al+Si)-rich nitride nanolayers observed by transmission electron microscopy (TEM).After thermal treatment of the samples for 1 h at 1000 °C under nitrogen, a significant hardness drop due to structural relaxation occurs for single-phase low-(Al+Si) coatings, indicating that the initial hardening effect was due mainly to compressive stresses in the films, caused by the ion bombardment conditions during deposition. For films of higher aluminium and silicon content this response is reversed and a hardness increase of about 2 GPa is measured. Since the nanolayer structures remain unaffected by the annealing according to TEM this behaviour evidently relates to the presence of a Ti1−xAlxN/SiNy nanocomposite, where the hardness increase is attributed to spinodal segregation completion during annealing. The oxidation rate during annealing depends on film composition and microstructure. The oxide layer formed on the top of the (Al+Si)-rich coatings consists of nano-grained Al2O3 at the oxide-coating interface, followed by a layer of discrete TiO2 and Al2O3 in the near-surface region. TEM revealed a non-uniform oxide-coating interface for columnar coatings, with preferential oxidation along the grain boundaries.
    Surface and Coatings Technology. 01/2004;
  • M. Parlinska-Wojtan, A. Karimi
    01/2003;
  • M Parlinska-Wojtan, A Karimi, T Cselle, M Morstein
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    ABSTRACT: Microstructure and growth mechanism of graded TiAlSiN thin films have been investigated using conventional and high-resolution transmission electron microscopy (TEM). The films, having a total thickness of approximately 2 μm, were deposited by arc plasma PVD technique on WC–Co substrates. The film region close to the substrate was engineered as Ti-rich, and with the growing film thickness the Al+Si content increased, although the Al/Si ratio remained constant. Selected area electron diffraction and local chemical analysis (EDX microanalysis) were used to determine the exact concentration of Ti, Al and Si in the coating, TEM and HRTEM of cross-sectional cuts through the coating revealed distinct microstructures in different film regions. The Ti-rich zone close to the substrate exhibited crystalline structure with pronounced columnar growth. The addition of Al+Si leads to a crystallite refinement in the central part of the coating. Chemically modulated nanolayers with a period of 5 nm were superposed on the weak columnar structure in this region. Further increasing of the Al+Si concentration resulted in the formation of nanocomposites consisting of equiaxial, crystalline nanograins surrounded by a disordered, amorphous SiNx matrix.
    Surface and Coatings Technology s 177–178:376–381. · 1.94 Impact Factor