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  • 1.
    Berlind, Torun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Furland, Andrej
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Czigany, Zs.
    Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, H-1525 Budapest, Hungary.
    Neidhardt, Jörg
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Spectroscopic ellipsometry characterization of amorphous carbon and amorphous,graphitic and fullerene-like carbon nitride thin films2009In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 517, no 24, 6652-6658 p.Article in journal (Refereed)
    Abstract [en]

    Carbon nitride (CNx) and amorphous carbon (a-C) thin films are deposited by reactive magnetron sputtering onto silicon (001) wafers under controlled conditions to achieve amorphous, graphitic and fullerene-like microstructures. As-deposited films are analyzed by Spectroscopic Ellipsometry in the UV–VIS–NIR and IR spectral ranges in order to get further insight into the bonding structure of the material. Additional characterization is performed by High Resolution Transmission Electron Microscopy, X-ray Photoelectron Spectroscopy, and Atomic Force Microscopy. Between eight and eleven resonances are observed and modeled in the ellipsometrically determined optical spectra of the films. The largest or the second largest resonance for all films is a feature associated with C–N or C–C modes. This feature is generally associated with sp3 C–N or sp3 C–C bonds, which for the nitrogen-containing films instead should be identified as a three-fold or two-fold sp2 hybridization of N, either substituted in a graphite site or in a pyridine-like configuration, respectively. The π→πlow asterisk electronic transition associated with sp2 C bonds in carbon films and with sp2 N bonds (as N bonded in pyridine-like manner) in CNx films is also present, but not as strong. Another feature present in all CNx films is a resonance associated with nitrile often observed in carbon nitrides. Additional resonances are identified and discussed and moreover, several new, unidentified resonances are observed in the ellipsometric spectra.

  • 2.
    Broitman, E.
    et al.
    Carnegie Mellon Univ, Dept Chem Engn, Pittsburgh, PA 15213 USA.
    Furlan, Andrej
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Kostov Gueorguiev, Gueorgui
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Czigany, Zs.
    Res Inst Tech Phys and Mat Sci, H-1525 Budapest, Hungary.
    Tarditi, A M
    Univ Nacl Litoral, RA-3000 Santa Fe, Argentina.
    Gellman, A J
    Carnegie Mellon Univ, Dept Chem Engn, Pittsburgh, PA 15213 USA.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Water adsorption on phosphorous-carbide thin films2009In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 204, no 6-7, 1035-1039 p.Article in journal (Refereed)
    Abstract [en]

    Amorphous phosphorous-carbide films have been considered as a new tribological coating material with unique electrical properties. However, such CPx films have not found practical use until now because they tend to oxidize/hydrolyze rapidly when in contact with air. Recently, we demonstrated that CPx thin films with a fullerene-like structure can be deposited by magnetron sputtering, whereby the structural incorporation of P atoms induces the formation of strongly bent and inter-linked graphene planes. Here, we compare the uptake of water in fullerene-like phosphorous-carbide (FL-CPx) thin films with that in amorphous phosphorous-carbide (a-CPx), and amorphous carbon (a-C) thin films. Films of each material were deposited on quartz crystal substrates by reactive DC magnetron sputtering to a thickness in the range 100-300 nm. The film microstructure was characterized by X-ray photoelectron spectroscopy, and high resolution transmission electron microscopy. A quartz crystal microbalance placed in a vacuum chamber was used to measure their water adsorption. Measurements indicate that FL-CPx films adsorbed less water than the a-CPx and a-C ones. To provide additional insight into the atomic structure of defects in the FL-CPx and a-CPx compounds, we performed first-principles calculations within the framework of density functional theory. Cohesive energy comparison reveals that the energy cost formation for dangling bonds in different configurations is considerably higher in FL-CPx than for the amorphous films. Thus, the modeling confirms the experimental results that dangling bonds are less likely in FL-CPx than in a-CPx and a-C films.

  • 3.
    Broitman, E
    et al.
    Carnegie Mellon University.
    Kostov Gueorguiev, Gueorgui
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Furlan, Andrej
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Son, Tien Nguyen
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Gellman, A J
    Carnegie Mellon University.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Hultman , Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Water adsorption on fullerene-like carbon nitride overcoats2008In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 517, no 3, 1106-1110 p.Article in journal (Refereed)
    Abstract [en]

    Humidity influences the tribological performance of the head-disk interface in magnetic data storage devices. In this work we compare the uptake of water of amorphous carbon nitride (a-CNx) films, widely used as protective overcoats in computer disk drive systems, with fullerene-like carbon nitride (FL-CNx) and amorphous carbon (a-C) films. Films with thickness in the range 10-300 run were deposited on quartz crystal substrates by reactive DC magnetron sputtering. A quartz crystal microbalance placed in a vacuum chamber was used to measure the water adsorption. Electron paramagnetic resonance (EPR) has been used to correlate water adsorption with film microstructure and surface defects (dangling bonds). Measurements indicate that the amount of adsorbed water is highest for the pure a-C films and that the FL-CNx films adsorbed less than a-CNx. EPR data correlate the lower water adsorption on FL-CNx films with a possible lack of dangling bonds on the film surface. To provide additional insight into the atomic structure of defects in the FL-CNx, a-CNx and a-C compounds, we performed first-principles calculations within the framework of Density Functional Theory. Emphasis was put on the energy cost for formation of vacancy defects and dangling bonds in relaxed systems. Cohesive energy comparison reveals that the energy cost formation for dangling bonds in different configurations is considerably higher in FL-CNx than for the amorphous films. These simulations thus confirm the experimental results showing that dangling bonds are much less likely in FL-CNx than in a-CNx and a-C films.

  • 4.
    Broitman, E.
    et al.
    Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
    Pushkarev, V. V.
    Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
    Gellman, A. J.
    Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
    Neidhardt, Jörg
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Furlan, Andrej
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Water adsorption on lubricated fullerene-like CNx films2006In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, no 3, 979-983 p.Article in journal (Refereed)
    Abstract [en]

    Humidity influences the tribological performance of the head–disk interface in magnetic data storage devices. In this work we compare the uptake of water of amorphous hydrogenated carbon (a-CHy) and carbon nitride (a-CNx) films, widely used as protective overcoats in computer disk drive systems, with two types of amorphous non-hydrogenated carbon (a-C and a-Csp2) films, and fullerene-like carbon nitride (FL-CNx) films. Carbon films were deposited on quartz crystal substrates by reactive dc magnetron sputtering in Ar/N2 discharges. After deposition, some of the films were coated with a 2-nm-thick layer of Z-tetraol, a lubricant used in hard disk devices. A quartz crystal microbalance placed in a vacuum chamber was used to measure the adsorption of water at room temperature and at pressures of water corresponding to relative humidities in the range RH = 0 to 90%. Water adsorption and desorption is fast, indicating that equilibrium with ambient humidity is reached on time scales of minutes, much faster than the time scales for fluctuations in ambient humidity. The amount of water adsorbed on the non-lubricated amorphous carbon films is significantly higher than that on the fullerene-like films. The presence of the lubricant influences water adsorption but its impact differs on different carbon films.

  • 5.
    Broitman, Esteban
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Furlan, Andrej
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Geuorguiev, G. K.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Czigany, Zsolt
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Högberg, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Structural and Mechanical Properties of CNx and CPx Thin Solid Films2012In: Key Engineering Materials, ISSN 1013-9826, E-ISSN 1662-9795, Vol. 488-489, 581-584 p.Article in journal (Refereed)
    Abstract [en]

    The inherent resiliency, hardness and relatively low friction coefficient of the fullerene-like (FL) allotrope of carbon nitride (CNx) thin solid films give them potential in numerous tribological applications. In this work, we study the substitution of N with P to grow FL-CPx to achieve better cross- and inter-linking of the graphene planes, improving thus the materials mechanical and tribological properties. The CNx and CPx films have been synthesized by DC magnetron sputtering. HRTEM have shown the CPx films exhibit a short range ordered structure with FL characteristics for substrate temperature of 300 degrees C and for a phosphorus content of 10-15 at.%. These films show better mechanical properties in terms of hardness and resiliency compared to those of the FL-CNx films. The low water adsorption of the films is correlated to the theoretical prediction for low density of dangling bonds in both, CNx and CPx. First-principles calculations based on Density Functional Theory (DFT) were performed to provide additional insight on the structure and bonding in CNx, CPx and a-C compounds.

  • 6.
    Furlan, Andrej
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Experiments and Theoretical Modeling of Fullerene-like CNx and CPx Thin Film Structures2007Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis concerns the materials science of carbon-based fullerene-like structures as a basis for the improvement of the applicability of FL-CNx protective thin films. In particular, structural origins of mechanical properties of FL-CNx coatings and water adsorption on their surface were investigated, both of which are critical parameters for their application as, e.g., computer hard disk protective coatings. Also, prospective FL-CPx structures were investigated by first-principles modeling. I present an introduction to theoretical methods used to study the effects of nitrogen and phosphorus as dopant elements. The modeling results include pure phosphorus clusters, mixed carbon-phosphorus clusters, and growth of fullerenelike phospho-carbide structures. Finally, I present some implications for the synthesis of FL-CPx thin films and the extension of the research to other dopant elements including sulphur, arsenic, and germanium.

    List of papers
    1. Water adsorption on lubricated fullerene-like CNx films
    Open this publication in new window or tab >>Water adsorption on lubricated fullerene-like CNx films
    Show others...
    2006 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, no 3, 979-983 p.Article in journal (Refereed) Published
    Abstract [en]

    Humidity influences the tribological performance of the head–disk interface in magnetic data storage devices. In this work we compare the uptake of water of amorphous hydrogenated carbon (a-CHy) and carbon nitride (a-CNx) films, widely used as protective overcoats in computer disk drive systems, with two types of amorphous non-hydrogenated carbon (a-C and a-Csp2) films, and fullerene-like carbon nitride (FL-CNx) films. Carbon films were deposited on quartz crystal substrates by reactive dc magnetron sputtering in Ar/N2 discharges. After deposition, some of the films were coated with a 2-nm-thick layer of Z-tetraol, a lubricant used in hard disk devices. A quartz crystal microbalance placed in a vacuum chamber was used to measure the adsorption of water at room temperature and at pressures of water corresponding to relative humidities in the range RH = 0 to 90%. Water adsorption and desorption is fast, indicating that equilibrium with ambient humidity is reached on time scales of minutes, much faster than the time scales for fluctuations in ambient humidity. The amount of water adsorbed on the non-lubricated amorphous carbon films is significantly higher than that on the fullerene-like films. The presence of the lubricant influences water adsorption but its impact differs on different carbon films.

    Keyword
    Carbon nitride, Water, Adsorption, Sputtering, Fullerene-like
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-14229 (URN)10.1016/j.tsf.2006.07.065 (DOI)
    Available from: 2007-01-26 Created: 2007-01-26 Last updated: 2017-12-13Bibliographically approved
    2. Fullerene–like CPx: A first–principles study of the relative stability of precursors and defect energetics during synthetic growth
    Open this publication in new window or tab >>Fullerene–like CPx: A first–principles study of the relative stability of precursors and defect energetics during synthetic growth
    Show others...
    2006 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, no 3, 1028-1032 p.Article in journal (Refereed) Published
    Abstract [en]

    Inherently nanostructured CPx compounds were studied by first-principles calculations. Geometry optimizations and cohesive energy comparisons show stability for C3P, C2P, C3P2, CP, and P4 (P2) species in isolated form as well as incorporated in graphene layers. The energy cost for structural defects, arising from the substitution of C for P and intercalation of P atoms in graphene, was also evaluated. We find a larger curvature of the graphene sheets and a higher density of cross-linkage sites in comparison to fullerene-like (FL) CNx, which is explained by differences in the bonding between P and N. Thus, the computational results extend the scope of fullerene-like thin film materials with FL-CPx and provide insights for its structural properties.

    Keyword
    Fullerene-like materials; Phosphorus carbide (CPx); First-principles calculations; Thin films; Precursors
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-14230 (URN)10.1016/j.tsf.2006.07.176 (DOI)
    Available from: 2007-01-26 Created: 2007-01-26 Last updated: 2017-12-13Bibliographically approved
    3. First–principles calculations on the structural evolution of solid fullerene–like CPx
    Open this publication in new window or tab >>First–principles calculations on the structural evolution of solid fullerene–like CPx
    Show others...
    2006 (English)In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 426, no 4-6, 374-379 p.Article in journal (Refereed) Published
    Abstract [en]

    The formation and structural evolution of fullerene-like (FL) carbon phosphide (CPx) during synthetic growth were studied by first-principles calculations. Geometry optimizations and comparison between the cohesive energies suggest stability for solid FL-CPx compounds. In comparison with fullerene-like carbon nitride, higher curvature of the graphene sheets and higher density of cross-linkages between them is predicted and explained by the different electronic properties of P and N. Cage-like and onion-like structures, both containing tetragons, are found to be typical for fullerene-like CPx. Segregation of P is predicted at fractions exceeding ~20 at.%.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-14231 (URN)10.1016/j.cplett.2006.05.087 (DOI)
    Available from: 2007-01-26 Created: 2007-01-26 Last updated: 2017-12-13Bibliographically approved
  • 7.
    Furlan, Andrej
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Fulerenom podobne tanke plasti CNx (Fullerene-like CNx Thin Solid Films)2006In: Vakuumist, ISSN 0351-9716, Vol. 26, 30-34 p.Article in journal (Refereed)
  • 8.
    Furlan, Andrej
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Fullerene-like CNx and CPx Thin Films; Synthesis, Modeling, and Applications2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This Thesis concerns the development of fullerene-like (FL) carbon nitride (CNx) thin films and the discovery of phosphorus-carbide (CPx) compounds. The work dedicated to CPx include first-principles theoretical simulations of the growth and properties of FL-CPx structures. I have employed DC magnetron sputtering methods to synthesize both CNx and CPx thin films. The deposition conditions for CPx films were chosen on the basis of the theoretical results as well as from the experience from the deposition of FL-CNx thin films.

    The characterization of the CPx films is divided into three main directions: structural characterization by transmission electron microscopyand scanning electron microscopy, analysis of the amount of elements and chemical bonds presentin the structure by X-ray photoelectron spectroscopy and Auger spectroscopy, and mechanicalproperty analysis by nanoindentation. The CPx films exhibit a short range orderedstructure with FL characteristics for substrate temperature of 300 °C and for a phosphorus content of 10-15 at.%, which isconsistent with the theoretical findings. These films also displayed the best mechanical properties in terms of hardness and resiliency, which are better than those of the corresponding FL-CNx films.

    For the FL-CNx thin film material, I find that the surface water adsorption is lower compared to commercial computer hard disk top coatings. Following that line the dangling bonds in FL-CNx coatings have been investigated  by electron spin resonance (ESR). The absence of ESR signal for FL-CNx indicates very low density of dangling bonds in the material, which explains the low water adsorption tendency.

    The potential for using highly elastic FL-CNx coatings in an automotive valve-train environment has also been investigated. CNx coatings of different nitrogen content were investigated using microscopy, wear testing, nanoindentation testing, and in an experimental cam-tappet testing rig. The FL-CNx coating with the higher value of hardness/elastic modulus showed greater durability in cam-tappet wear testing.

    List of papers
    1. Fullerene–like CPx: A first–principles study of the relative stability of precursors and defect energetics during synthetic growth
    Open this publication in new window or tab >>Fullerene–like CPx: A first–principles study of the relative stability of precursors and defect energetics during synthetic growth
    Show others...
    2006 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, no 3, 1028-1032 p.Article in journal (Refereed) Published
    Abstract [en]

    Inherently nanostructured CPx compounds were studied by first-principles calculations. Geometry optimizations and cohesive energy comparisons show stability for C3P, C2P, C3P2, CP, and P4 (P2) species in isolated form as well as incorporated in graphene layers. The energy cost for structural defects, arising from the substitution of C for P and intercalation of P atoms in graphene, was also evaluated. We find a larger curvature of the graphene sheets and a higher density of cross-linkage sites in comparison to fullerene-like (FL) CNx, which is explained by differences in the bonding between P and N. Thus, the computational results extend the scope of fullerene-like thin film materials with FL-CPx and provide insights for its structural properties.

    Keyword
    Fullerene-like materials; Phosphorus carbide (CPx); First-principles calculations; Thin films; Precursors
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-14230 (URN)10.1016/j.tsf.2006.07.176 (DOI)
    Available from: 2007-01-26 Created: 2007-01-26 Last updated: 2017-12-13Bibliographically approved
    2. First–principles calculations on the structural evolution of solid fullerene–like CPx
    Open this publication in new window or tab >>First–principles calculations on the structural evolution of solid fullerene–like CPx
    Show others...
    2006 (English)In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 426, no 4-6, 374-379 p.Article in journal (Refereed) Published
    Abstract [en]

    The formation and structural evolution of fullerene-like (FL) carbon phosphide (CPx) during synthetic growth were studied by first-principles calculations. Geometry optimizations and comparison between the cohesive energies suggest stability for solid FL-CPx compounds. In comparison with fullerene-like carbon nitride, higher curvature of the graphene sheets and higher density of cross-linkages between them is predicted and explained by the different electronic properties of P and N. Cage-like and onion-like structures, both containing tetragons, are found to be typical for fullerene-like CPx. Segregation of P is predicted at fractions exceeding ~20 at.%.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-14231 (URN)10.1016/j.cplett.2006.05.087 (DOI)
    Available from: 2007-01-26 Created: 2007-01-26 Last updated: 2017-12-13Bibliographically approved
    3. Synthesis of phosphorus-carbide thin films by magnetron sputtering
    Open this publication in new window or tab >>Synthesis of phosphorus-carbide thin films by magnetron sputtering
    Show others...
    2008 (English)In: physica status solidi (RRL) - Rapid Research Letters, ISSN 1862-6254, Vol. 2, no 4, 191-193 p.Article in journal (Refereed) Published
    Abstract [en]

    Phosphorus-carbide, CPx (0.025≤x≤0.1) thin films have beensynthesized by magnetron sputtering from pressed graphite-phosphorustargets. The films were characterized by X-ray photoelectron spectroscopy,transmission electron microscopy and diffraction, andnanoindentation. CP0.02 exhibits C-P bonding in an amorphous structure with elements of curved grapheneplanes, yielding a material with unique short range order. These features are consistent with what has been predicted by our results of theoreticallymodeled synthetic growth of CPx. The films are mechanicallyresilient with hardness up to 24 GPa and elastic recovery upto 72%.

    Place, publisher, year, edition, pages
    Wiley InterScience, 2008
    Keyword
    Phosphorus-carbide (CPx), thin films, magnetron sputtering, resilient material
    National Category
    Other Engineering and Technologies not elsewhere specified
    Identifiers
    urn:nbn:se:liu:diva-17114 (URN)
    Available from: 2009-03-06 Created: 2009-03-06 Last updated: 2016-08-31Bibliographically approved
    4. Structure and properties of phosphorus-carbide thin solid films
    Open this publication in new window or tab >>Structure and properties of phosphorus-carbide thin solid films
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    2013 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 548, no 2, 247-254 p.Article in journal (Refereed) Published
    Abstract [en]

    Phosphorus-carbide (CPx) thin films have been deposited by unbalanced reactive magnetron sputtering and investigated by TEM, XPS, SEM, ERDA, Raman scattering spectroscopy, nanoindentation testing, and four-point electrical probe techniques. As-deposited films with x=0.1 are electron amorphous with elements of FL structure and high mechanical resiliency with hardness of 34.4 GPa and elastic recovery of 72%. The electrical resistivity of the films are in the range 0.4-1.7 Ωcm for CP0.027, 1.4-22.9 Ωcm for CP0.1, and lower than the minimal value the four-point probe is able to detect for CPx with x≥0.2.

    Keyword
    Phosphorus carbide, thin films, magnetron sputtering
    National Category
    Other Engineering and Technologies not elsewhere specified
    Identifiers
    urn:nbn:se:liu:diva-17058 (URN)10.1016/j.tsf.2013.10.010 (DOI)000327530300039 ()
    Available from: 2009-03-04 Created: 2009-03-04 Last updated: 2017-12-13Bibliographically approved
    5. Water adsorption on lubricated fullerene-like CNx films
    Open this publication in new window or tab >>Water adsorption on lubricated fullerene-like CNx films
    Show others...
    2006 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, no 3, 979-983 p.Article in journal (Refereed) Published
    Abstract [en]

    Humidity influences the tribological performance of the head–disk interface in magnetic data storage devices. In this work we compare the uptake of water of amorphous hydrogenated carbon (a-CHy) and carbon nitride (a-CNx) films, widely used as protective overcoats in computer disk drive systems, with two types of amorphous non-hydrogenated carbon (a-C and a-Csp2) films, and fullerene-like carbon nitride (FL-CNx) films. Carbon films were deposited on quartz crystal substrates by reactive dc magnetron sputtering in Ar/N2 discharges. After deposition, some of the films were coated with a 2-nm-thick layer of Z-tetraol, a lubricant used in hard disk devices. A quartz crystal microbalance placed in a vacuum chamber was used to measure the adsorption of water at room temperature and at pressures of water corresponding to relative humidities in the range RH = 0 to 90%. Water adsorption and desorption is fast, indicating that equilibrium with ambient humidity is reached on time scales of minutes, much faster than the time scales for fluctuations in ambient humidity. The amount of water adsorbed on the non-lubricated amorphous carbon films is significantly higher than that on the fullerene-like films. The presence of the lubricant influences water adsorption but its impact differs on different carbon films.

    Keyword
    Carbon nitride, Water, Adsorption, Sputtering, Fullerene-like
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-14229 (URN)10.1016/j.tsf.2006.07.065 (DOI)
    Available from: 2007-01-26 Created: 2007-01-26 Last updated: 2017-12-13Bibliographically approved
    6. Water adsorption on fullerene-like carbon nitride overcoats
    Open this publication in new window or tab >>Water adsorption on fullerene-like carbon nitride overcoats
    Show others...
    2008 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 517, no 3, 1106-1110 p.Article in journal (Refereed) Published
    Abstract [en]

    Humidity influences the tribological performance of the head-disk interface in magnetic data storage devices. In this work we compare the uptake of water of amorphous carbon nitride (a-CNx) films, widely used as protective overcoats in computer disk drive systems, with fullerene-like carbon nitride (FL-CNx) and amorphous carbon (a-C) films. Films with thickness in the range 10-300 run were deposited on quartz crystal substrates by reactive DC magnetron sputtering. A quartz crystal microbalance placed in a vacuum chamber was used to measure the water adsorption. Electron paramagnetic resonance (EPR) has been used to correlate water adsorption with film microstructure and surface defects (dangling bonds). Measurements indicate that the amount of adsorbed water is highest for the pure a-C films and that the FL-CNx films adsorbed less than a-CNx. EPR data correlate the lower water adsorption on FL-CNx films with a possible lack of dangling bonds on the film surface. To provide additional insight into the atomic structure of defects in the FL-CNx, a-CNx and a-C compounds, we performed first-principles calculations within the framework of Density Functional Theory. Emphasis was put on the energy cost for formation of vacancy defects and dangling bonds in relaxed systems. Cohesive energy comparison reveals that the energy cost formation for dangling bonds in different configurations is considerably higher in FL-CNx than for the amorphous films. These simulations thus confirm the experimental results showing that dangling bonds are much less likely in FL-CNx than in a-CNx and a-C films.

    Keyword
    Carbon nitride, CNx, dangling bonds, water adsorption, QCM, EPR, DFT
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-16402 (URN)10.1016/j.tsf.2008.07.022 (DOI)
    Note
    Presented at the 35th International Conference on Metallurgical Coatings and Thin Films (ICMCTF), San Diego, USAAvailable from: 2009-01-23 Created: 2009-01-23 Last updated: 2017-12-14Bibliographically approved
    7. Performance of fullerene-like CNx coatings for automotive valve-train applications
    Open this publication in new window or tab >>Performance of fullerene-like CNx coatings for automotive valve-train applications
    (English)Manuscript (Other academic)
    Abstract [en]

    The design of internal combustion engines is evolving in order to provide greater efficiency and lower harmful emissions. There has been a move to lower component masses, higher engine temperatures, lower viscosity oils and low SAPS (sulphated ash, phosphor and sulphur) oils. With the transition to low density, low hardness materials and new lubrication conditions, come issues of component wear. Surface engineering techniques such as thin-film coating technologies present a possible solution. Thin-film coating development in recent years has often focused on achieving a high hardness, which often leads to high elastic modulus. However, there are potential benefits of less stiff and more elastic coatings. A number of wear mechanism are directly related to the ratio of hardness (H) and elastic modulus (E) and higher H/E ratios can be beneficial. This work therefore investigates the potential for using a highly elastic, experimental fullerene-like carbon nitride (FL-CNx) coating in a valve-train environment. Two FL-CNx coatings of differing nitrogen content were investigated using microscopy, wear testing, nanoindentation testing and in an experimental cam-tappet testing rig. The two FL-CNx coatings had similar adhesion to the substrate and hardness. The FL-CNx coating with the higher value of H/E also showed greater durability in the valve-train testing.

    Keyword
    Fullerene-like materials, automotive valve-train, applications
    National Category
    Other Engineering and Technologies not elsewhere specified
    Identifiers
    urn:nbn:se:liu:diva-17060 (URN)
    Available from: 2009-03-04 Created: 2009-03-04 Last updated: 2016-08-31Bibliographically approved
  • 9.
    Furlan, Andrej
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Gueorguiev, Gueorgui Kostov
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Czigány, Zsolt
    Research Institute for Technical Physics and Materials Science, P.O. Box 49, Budapest, H-1525, Hungary.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Correia, Rosario
    I3N and Physics Department, University of Aveiro, 3810-193 Aveiro, Portugal.
    Högberg, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Structure and properties of phosphorus-carbide thin solid films2013In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 548, no 2, 247-254 p.Article in journal (Refereed)
    Abstract [en]

    Phosphorus-carbide (CPx) thin films have been deposited by unbalanced reactive magnetron sputtering and investigated by TEM, XPS, SEM, ERDA, Raman scattering spectroscopy, nanoindentation testing, and four-point electrical probe techniques. As-deposited films with x=0.1 are electron amorphous with elements of FL structure and high mechanical resiliency with hardness of 34.4 GPa and elastic recovery of 72%. The electrical resistivity of the films are in the range 0.4-1.7 Ωcm for CP0.027, 1.4-22.9 Ωcm for CP0.1, and lower than the minimal value the four-point probe is able to detect for CPx with x≥0.2.

  • 10.
    Furlan, Andrej
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Gueorguiev, Gueorgui Kostov
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Czigány, Zsolt
    Research Institute for Technical Physics and Materials Science, P.O. Box 49, Budapest, Hungary.
    Högberg, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Braun, Slawomir
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Synthesis of phosphorus-carbide thin films by magnetron sputtering2008In: physica status solidi (RRL) - Rapid Research Letters, ISSN 1862-6254, Vol. 2, no 4, 191-193 p.Article in journal (Refereed)
    Abstract [en]

    Phosphorus-carbide, CPx (0.025≤x≤0.1) thin films have beensynthesized by magnetron sputtering from pressed graphite-phosphorustargets. The films were characterized by X-ray photoelectron spectroscopy,transmission electron microscopy and diffraction, andnanoindentation. CP0.02 exhibits C-P bonding in an amorphous structure with elements of curved grapheneplanes, yielding a material with unique short range order. These features are consistent with what has been predicted by our results of theoreticallymodeled synthetic growth of CPx. The films are mechanicallyresilient with hardness up to 24 GPa and elastic recovery upto 72%.

  • 11.
    Furlan, Andrej
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Gueorguiev, Gueorgui Kostov
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Högberg, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Fullerene–like CPx: A first–principles study of the relative stability of precursors and defect energetics during synthetic growth2006In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 515, no 3, 1028-1032 p.Article in journal (Refereed)
    Abstract [en]

    Inherently nanostructured CPx compounds were studied by first-principles calculations. Geometry optimizations and cohesive energy comparisons show stability for C3P, C2P, C3P2, CP, and P4 (P2) species in isolated form as well as incorporated in graphene layers. The energy cost for structural defects, arising from the substitution of C for P and intercalation of P atoms in graphene, was also evaluated. We find a larger curvature of the graphene sheets and a higher density of cross-linkage sites in comparison to fullerene-like (FL) CNx, which is explained by differences in the bonding between P and N. Thus, the computational results extend the scope of fullerene-like thin film materials with FL-CPx and provide insights for its structural properties.

  • 12.
    Furlan, Andrej
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jansson, Ulf
    Ångström Laboratory, Uppsala University, Uppsala, Sweden.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Magnuson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Structure and bonding in amorphous iron carbide thin films2015In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 27, no 4, 045002- p.Article in journal (Refereed)
    Abstract [en]

    We investigate the amorphous structure, chemical bonding, and electrical properties ofmagnetron sputtered Fe1−xCx (0.21 < x < 0.72) thin films. X-ray, electron diffraction andtransmission electron microscopy show that the Fe1−xCx films are amorphousnanocomposites, consisting of a two-phase domain structure with Fe-rich carbidic FeCy , and acarbon-rich matrix. Pair distribution function analysis indicates a close-range order similar tothose of crystalline Fe3C carbides in all films with additional graphene-like structures at highcarbon content (71.8 at% C). From x-ray photoelectron spectroscopy measurements, we findthat the amorphous carbidic phase has a composition of 15–25 at% carbon that slightlyincreases with total carbon content. X-ray absorption spectra exhibit an increasing number ofunoccupied 3d states and a decreasing number of C 2p states as a function of carbon content.These changes signify a systematic redistribution in orbital occupation due to charge-transfereffects at the domain-size-dependent carbide/matrix interfaces. The four-point proberesistivity of the Fe1−xCx films increases exponentially with carbon content from ∼200μcm(x = 0.21) to ∼1200μcm (x = 0.72), and is found to depend on the total carbon contentrather than the composition of the carbide. Our findings open new possibilities for modifyingthe resistivity of amorphous thin film coatings based on transition metal carbides through thecontrol of amorphous domain structures.

  • 13.
    Furlan, Andrej
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jansson, Ulf
    Uppsala University, Sweden .
    Magnuson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Crystallization characteristics and chemical bonding properties of nickel carbide thin film nanocomposites2014In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 26, no 41, 415501-415512 p.Article in journal (Refereed)
    Abstract [en]

    The crystal structure and chemical bonding of magnetron-sputtering deposited nickel carbide Ni1−xCx (0.05≤x≤0.62) thin films have been investigated by high-resolution x-ray diffraction, transmission electron microscopy, x-ray photoelectron spectroscopy, Raman spectroscopy, and soft x-ray absorption spectroscopy. By using x-ray as well as electron diffraction, we found carbon-containing hcp-Ni (hcp-NiCy phase), instead of the expected rhombohedral-Ni3C. At low carbon content (4.9 at%), the thin film consists of hcp-NiCy nanocrystallites mixed with a smaller amount of fcc-NiCx. The average grain size is about10–20 nm. With the increase of carbon content to 16.3 at%, the film contains single-phase hcp-NiCy nanocrystallites with expanded lattice parameters. With a further increase of carbon content to 38 at%, and 62 at%, the films transform to x-ray amorphous materials with hcp-NiCy and fcc-NiCx nanodomain structures in an amorphous carbon-rich matrix. Raman spectra of carbon indicate dominant sp2 hybridization, consistent with photoelectron spectra that show a decreasing amount of C–Ni phase with increasing carbon content. The Ni 3d–C 2p hybridization in the hexagonal structure gives rise to the salient double-peak structure in Ni 2p soft x-ray absorption spectra at 16.3 at% that changes with carbon content. We also show thatthe resistivity is not only governed by the amount of carbon, but increases by more than a factor of two when the samples transform from crystalline to amorphous.

  • 14.
    Gueorguiev, Gueorgui Kostov
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Furlan, Andrej
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Högberg, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    First–principles calculations on the structural evolution of solid fullerene–like CPx2006In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 426, no 4-6, 374-379 p.Article in journal (Refereed)
    Abstract [en]

    The formation and structural evolution of fullerene-like (FL) carbon phosphide (CPx) during synthetic growth were studied by first-principles calculations. Geometry optimizations and comparison between the cohesive energies suggest stability for solid FL-CPx compounds. In comparison with fullerene-like carbon nitride, higher curvature of the graphene sheets and higher density of cross-linkages between them is predicted and explained by the different electronic properties of P and N. Cage-like and onion-like structures, both containing tetragons, are found to be typical for fullerene-like CPx. Segregation of P is predicted at fractions exceeding ~20 at.%.

  • 15.
    Kostov Gueorguiev, Gueorgui
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Broitman, E
    Carnegie Mellon University.
    Furlan, Andrej
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Dangling bond energetics in carbon nitride and phosphorus carbide thin films with fullerene-like and amorphous structure2009In: CHEMICAL PHYSICS LETTERS, ISSN 0009-2614, Vol. 482, no 1-3, 110-113 p.Article in journal (Refereed)
    Abstract [en]

    The energy cost for dangling bond formation in Fullerene-like Carbon Nitride (FL-CNx) and Phosphorus carbide (FL-CPx) as well as their amorphous counterparts: a-CNx, a-CPx, and a-C has been calculated within the framework of Density Functional Theory and compared with surface water adsorption measurements. The highest energy cost is found in the FL-CNx ( about 1.37 eV) followed by FL-CPx compounds (0.62-1.04 eV). (C) 2009 Elsevier B. V. All rights reserved.

  • 16.
    Kostov Gueorguiev, Gueorgui
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Czigany, Zs
    Hungarian Academy of Science.
    Furlan, Andrej
    Uppsala University.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Intercalation of P atoms in Fullerene-like CPx2011In: CHEMICAL PHYSICS LETTERS, ISSN 0009-2614, Vol. 501, no 4-6, 400-403 p.Article in journal (Refereed)
    Abstract [en]

    The energy cost for P atom intercalation and corresponding structural implications during formation of Fullerene-like Phosphorus carbide (FL-CPx) were evaluated within the framework of Density Functional Theory. Single P atom interstitial defects in FL-CPx are energetically feasible and exhibit energy cost of 0.93-1.21 eV, which is comparable to the energy cost for experimentally confirmed tetragon defects and dangling bonds in CPx. A single P atom intercalation event in FL-CPx can increase the inter-sheet distance from 3.39-3.62 angstrom to 5.81-7.04 angstrom. These theoretical results are corroborated by Selected Area Electron Diffraction characterization of FL-CPx samples.

  • 17.
    Lawes, Simon D. A.
    et al.
    Department of Engineering, University of Leicester, University Road, Leicester, LE1, 7RH, UK.
    Furlan, Andrej
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hainsworth, Sarah W.
    Department of Engineering, University of Leicester, University Road, Leicester, LE1, 7RH, UK.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Performance of fullerene-like CNx coatings for automotive valve-train applicationsManuscript (Other academic)
    Abstract [en]

    The design of internal combustion engines is evolving in order to provide greater efficiency and lower harmful emissions. There has been a move to lower component masses, higher engine temperatures, lower viscosity oils and low SAPS (sulphated ash, phosphor and sulphur) oils. With the transition to low density, low hardness materials and new lubrication conditions, come issues of component wear. Surface engineering techniques such as thin-film coating technologies present a possible solution. Thin-film coating development in recent years has often focused on achieving a high hardness, which often leads to high elastic modulus. However, there are potential benefits of less stiff and more elastic coatings. A number of wear mechanism are directly related to the ratio of hardness (H) and elastic modulus (E) and higher H/E ratios can be beneficial. This work therefore investigates the potential for using a highly elastic, experimental fullerene-like carbon nitride (FL-CNx) coating in a valve-train environment. Two FL-CNx coatings of differing nitrogen content were investigated using microscopy, wear testing, nanoindentation testing and in an experimental cam-tappet testing rig. The two FL-CNx coatings had similar adhesion to the substrate and hardness. The FL-CNx coating with the higher value of H/E also showed greater durability in the valve-train testing.

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