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  • 1.
    Avdeev, M. V.
    et al.
    Joint Inst Nucl Res, Frank Lab Neutron Phys, Dubna 141980, Moscow Reg, Russia..
    Petrenko, V. I.
    Joint Inst Nucl Res, Frank Lab Neutron Phys, Dubna 141980, Moscow Reg, Russia.;Kyiv Taras Shevchenko Natl Univ, Kiev, Ukraine..
    Gapon, I. V.
    Joint Inst Nucl Res, Frank Lab Neutron Phys, Dubna 141980, Moscow Reg, Russia.;Kyiv Taras Shevchenko Natl Univ, Kiev, Ukraine..
    Bulavin, L. A.
    Kyiv Taras Shevchenko Natl Univ, Kiev, Ukraine..
    Vorobiev, Alexey A.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Soltwedel, O.
    Max Planck Inst Solid State Res, Outstn MLZ, Garching, Germany..
    Balasoiu, M.
    Joint Inst Nucl Res, Frank Lab Neutron Phys, Dubna 141980, Moscow Reg, Russia.;Natl Inst Phys & Nucl Engn, Bucharest, Romania..
    Vekas, L.
    Acad Romana, Ctr Fundamental & Adv Tech Res, Timisoara Branch, Timisoara, Romania..
    Zavisova, V.
    SAS, Inst Expt Phys, Kosice, Slovakia..
    Kopcansky, P.
    SAS, Inst Expt Phys, Kosice, Slovakia..
    Comparative structure analysis of magnetic fluids at interface with silicon by neutron reflectometry2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 352, p. 49-53Article in journal (Refereed)
    Abstract [en]

    The adsorption of surfactant coated magnetic nanoparticles from highly stable magnetic fluids on crystalline functionalized silicon is studied by neutron reflectometry. Two types of magnetic fluids based on nanomagnetite dispersed and stabilized in non-polar organic solvent (deuterated benzene) and strongly polar solvent (heavy water) are considered. In both cases the interface shows the formation of just one well-defined adsorption layer of nanoparticles, which is insensitive to the effect of the external magnetic field. Still, the particle concentration in the benzene-based fluid is higher in the vicinity to the silicon surface as compared to the bulk distribution. Despite the presence of an aggregate fraction in the water-based system the width of the adsorption layer is consistent with the size of separated particles, thus showing the preferable adsorption of non-aggregated particles.

  • 2. Bandyopadhyay, Sulalit
    et al.
    Singh, Gurvinder
    Sandvig, Ioanna
    Sandvig, Axel
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Kumar Puri, Anil
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Glomm, Wilhelm Robert
    Synthesis and in vitro cellular interactions of superparamagnetic iron nanoparticles with a crystalline gold shell2014In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 316, p. 171-178Article in journal (Refereed)
    Abstract [en]

    Fe@Au core-shell nanoparticles (NPs) exhibit multiple functionalities enabling their effective use in applications such as medical imaging and drug delivery. In this work, a novel synthetic method was developed and optimized for the synthesis of highly stable, monodisperse Fe@Au NPs of average diameter similar to 24 nm exhibiting magneto-plasmonic characteristics. Fe@Au NPs were characterized by a wide range of experimental techniques, including scanning (transmission) electron microscopy (S(T)EM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) and UV-vis spectroscopy. The formed particles comprise an amorphous iron core with a crystalline Au shell of tunable thickness, and retain the superparamagnetic properties at room temperature after formation of a crystalline Au shell. After surface modification, PEGylated Fe@Au NPs were used for in vitro studies on olfactory ensheathing cells (OECs) and human neural stem cells (hNSCs). No adverse effects of the Fe@Au particles were observed post-labeling, both cell types retaining normal morphology, viability, proliferation, and motility. It can be concluded that no appreciable toxic effects on both cell types, coupled with multifunctionality and chemical stability make them ideal candidates for therapeutic as well as diagnostic applications.

  • 3.
    Berner, Simon
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Lidbaum, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ledung, G.
    Åhlund, John
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Nilson, Katharina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Schiessling, Joachim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Gelius, Ulrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Bäckwall, J. E.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Oscarsson, Sven
    Electronic and structural studies of immobilized thiol-derivatized cobalt porphyrins on gold surfaces2007In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 253, no 18, p. 7540-7548Article in journal (Refereed)
    Abstract [en]

    The immobilisation of thiol-derivatized cobalt porphyrins on gold surfaces has been studied in detail by means of combined scanning tunnelling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). S-thioacetyl has been used as a protective group for the thiol. Different routes for deprotection of the acetyl groups were performed in acidic and in basic conditions. The results show the formation of monolayer films for the different preparation schemes. The immobilisation of the molecules on the gold surface takes place through the thiol-linkers by the formation of multiple thiolate bonds. In the case of layers formed with protected porphyrins approximately 60% of the linkers are bonded to the gold surface whereas for deprotected layers the amount of bonded linkers is increased up to about 80%. STM measurements revealed that the molecules arrange in a disordered overlayer and do not exhibit mobility on the gold surface. Annealing experiments have been performed in order to test the stability of the porphyrin layers. Disordered patterns have been observed in the STM images after annealing at T = 400 °C. XPS revealed that the sulphur content disappeared completely after annealing at T = 180 °C and that the molecules did undergo significant modifications.

  • 4.
    Borges, J.
    et al.
    Czech Tech Univ, Fac Elect Engn, Dept Control Engn, Tech 2, CR-16635 Prague 6, Czech Republic..
    Rodrigues, M. S.
    Univ Minho, Ctr Fis, P-4710057 Braga, Portugal.;Inst Pedro Nunes, Lab Ensaios Desgaste & Mat, P-3030199 Coimbra, Portugal..
    Lopes, C.
    Univ Minho, Ctr Fis, P-4710057 Braga, Portugal..
    Costa, D.
    Univ Minho, Ctr Fis, P-4710057 Braga, Portugal..
    Couto, F. M.
    Norte Fluminense State Univ, Phys Sci Lab, BR-28013602 Campos, RJ, Brazil..
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Martins, B.
    Inst Pedro Nunes, Lab Ensaios Desgaste & Mat, P-3030199 Coimbra, Portugal..
    Duarte, N.
    Inst Pedro Nunes, Lab Ensaios Desgaste & Mat, P-3030199 Coimbra, Portugal..
    Dias, J. P.
    Inst Pedro Nunes, Lab Ensaios Desgaste & Mat, P-3030199 Coimbra, Portugal..
    Cavaleiro, A.
    Univ Coimbra, Dept Mech Engn, SEG CEMUC, P-3030788 Coimbra, Portugal..
    Polcar, T.
    Czech Tech Univ, Fac Elect Engn, Dept Control Engn, Tech 2, CR-16635 Prague 6, Czech Republic.;Univ Southampton, Natl Ctr Adv Tribol Southampton, Southampton SO17 1BJ, Hants, England..
    Macedo, F.
    Univ Minho, Ctr Fis, P-4710057 Braga, Portugal..
    Vaz, F.
    Univ Minho, Ctr Fis, P-4710057 Braga, Portugal..
    Thin films composed of Ag nanoclusters dispersed in TiO2: Influence of composition and thermal annealing on the microstructure and physical responses2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 358, p. 595-604Article in journal (Refereed)
    Abstract [en]

    Noble metal powders containing gold and silver have been used for many centuries, providing different colours in the windows of the medieval cathedrals and in ancient Roman glasses. Nowadays, the interest in nanocomposite materials containing noble nanoparticles embedded in dielectric matrices is related with their potential use for a wide range of advanced technological applications. They have been proposed for environmental and biological sensing, tailoring colour of functional coatings, or for surface enhanced Raman spectroscopy. Most of these applications rely on the so-called localised surface plasmon resonance absorption, which is governed by the type of the noble metal nanoparticles, their distribution, size and shape and as well as of the dielectric characteristics of the host matrix. The aim of this work is to study the influence of the composition and thermal annealing on the morphological and structural changes of thin films composed of Ag metal clusters embedded in a dielectric TiO2 matrix. Since changes in size, shape and distribution of the clusters are fundamental parameters for tailoring the properties of plasmonic materials, a set of films with different Ag concentrations was prepared. The optical properties and the thermal behaviour of the films were correlated with the structural and morphological changes promoted by annealing. The films were deposited by DC magnetron sputtering and in order to promote the clustering of the Ag nanoparticles the as-deposited samples were subjected to an in-air annealing protocol. It was demonstrated that the clustering of metallic Ag affects the optical response spectrum and the thermal behaviour of the films.

  • 5.
    Brohede, Ulrika
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Zhao, Shuxi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Lindberg, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Forsgren, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    A novel graded bioactive high adhesion implant coating2009In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 255, no 17, p. 7723-7728Article in journal (Refereed)
    Abstract [en]

     One method to increase the clinical success rate of metal implants is to increase their bone bonding properties, i.e. to develop a bone   bioactive surface leading to reduced risks of interfacial problems.   Much research has been devoted to modifying the surface of metals to   make them become bioactive. Many of the proposed methods include   depositing a coating on the implant. However, there is a risk of coating failure due to low substrate adhesion. This paper describes a method to obtain bioactivity combined with a high coating adhesion via   a gradient structure of the coating. Gradient coatings were deposited   on Ti (grade 5) using reactive magnetron sputtering with increasing   oxygen content. To increase the grain size in the coating, all coatings   were post annealed at 385 degrees C. The obtained coating exhibited a gradual transition over 70 nm from crystalline titanium oxide (anatase)  at the surface to metallic Ti in the substrate, as shown using  cross-section transmission electron microscopy and X-ray photoelectron   spectroscopy depth pro. ling. Using scratch testing, it could be shown that the adhesion to the substrate was well above 1 GPa. The bioactivity of the coating was verified in vitro by the spontaneous   formation of hydroxylapatite upon storage in phosphate buffer solution at 37 degrees C for one week.   The described process can be applied to implants irrespective of bulk  metal in the base and should introduce the possibility to create safer permanent implants like reconstructive devices, dental, or spinal implants.

  • 6.
    Chakarov, D V
    et al.
    Chalmers University of Technology.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Hellsing, B
    Chalmers University of Technology.
    Kasemo, B
    Chalmers University of Technology.
    Photos induced desorption and intercalation of potassium atoms deposited on graphite(0001)1996In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 106, p. 186-192Article in journal (Refereed)
    Abstract [en]

    In addition to the photodesorption phenomenon previously observed for single K atoms from a graphite surface covered with a monolayer of potassium we present new results related to the photon stimulated interaction of potassium with graphite, which concerns alternative routes for energy relaxation of the photo excited K adatoms: photoinduced intercalation. The desorption yield has a threshold at h omega approximate to 3 eV and a maximum at h omega(max) approximate to 4.9 eV, Polarization measurements indicate a substrate-mediated mechanism. The coverage dependence suggests that only the ionic 2D, K-phase is photo active. The proposed mechanism includes attachment of photo-generated hot electrons to the K 4s adsorbate resonance of energy E(res). Assuming an analogous excitation process we discuss different mechanisms for the K photo intercalation and possible applications of the photon stimulated doping of carboneous materials at low temperature.

  • 7.
    Chow, Winnie W. Y.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Herwik, Stanislav
    Ruther, Patrick
    Göthelid, Emmanuelle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Oscarsson, Sven
    Bio-polymer coatings on neural probe surfaces: Influence of the initial sample composition2012In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 258, no 20, p. 7864-7871Article in journal (Refereed)
    Abstract [en]

    This paper presents the results of the study of hyaluronic acid (HyA) coating on two structural materials, silicon oxide (dielectric) surface and platinum (Pt) surface used for fabrication of probes developed for neurological investigations in the framework of the EU-project NeuroProbes. The silicon-based neural probes consist of multiple Pt electrodes on the probe shafts for neural recording applications. HyA coatings were proposed to apply on the probe surfaces to enhance the biocompatibility [1]. This study aims at understanding the influence of the initial composition of the probe surface on the structure and morphology of HyA coating. HyA was chemically functionalized by SS-pyridin using (N-Succinimidyl 3-[2-pyridyldithio]-propionate) (SPDP) and was immobilized on the surfaces via a covalent bond. The dielectric and Pt surfaces were derivatized by use of (3-mercaptopropyl) methyldimethoxysilane (MPMDMS). The silanol groups in MPMDMS bind to the dielectric surface, leaving the thiol groups at the uppermost surface and the thiol groups then bind covalently to the functionalized HyA. On the Pt surface, it is the thiol group which binds on the Pt surface. The coated surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). A well-defined HyA layer was observed on both dielectric and Pt surfaces. The coating of two molecular weights (340 kDa and 1.3 MDa) of HyA was examined. The influence of the silanized layer on the HyA coating was also investigated. 

  • 8.
    Espinoza, Shirly
    et al.
    Czech Acad Sci, Inst Phys, ELI Beamlines, Na Slovance 2, Prague 18221, Czech Republic..
    Neuber, Gerd
    Univ Hamburg, Inst Nanostruct & Solid State Phys, Ctr Free Electron Laser Sci, Adv Study Grp APOG, Luruper Chaussee 149, D-22761 Hamburg, Germany..
    Brooks, Christopher D.
    Czech Acad Sci, Inst Phys, ELI Beamlines, Na Slovance 2, Prague 18221, Czech Republic..
    Besner, Bastian
    Univ Hamburg, Inst Nanostruct & Solid State Phys, Ctr Free Electron Laser Sci, Adv Study Grp APOG, Luruper Chaussee 149, D-22761 Hamburg, Germany..
    Hashemi, Maryam
    4 DOS GmbH, Wehmerweg 26, D-22529 Hamburg, Germany..
    Ruebhausen, Michael
    Univ Hamburg, Inst Nanostruct & Solid State Phys, Ctr Free Electron Laser Sci, Adv Study Grp APOG, Luruper Chaussee 149, D-22761 Hamburg, Germany..
    Andreasson, Jakob
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics. Czech Acad Sci, Inst Phys, ELI Beamlines, Na Slovance 2, Prague 18221, Czech Republic.; Chalmers, Dept Phys, Condensed Matter Phys, Kemigarden 1, SE-41296 Gothenburg, Sweden..
    User oriented end-station on VUV pump-probe magneto-optical ellipsometry at ELI beamlines2017In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 421, no Part B, p. 378-382Article in journal (Refereed)
    Abstract [en]

    A state of the art ellipsometer for user operations is being implemented at ELI Beamlines in Prague, Czech Republic. It combines three of the most promising and exotic forms of ellipsometry: VUV, pump-probe and magneto-optical ellipsometry. This new ellipsometer covers a spectral operational range from the NIR up to the VUV, with high through-put between 1 and 40 eV. The ellipsometer also allows measurements of magneto-optical spectra with a 1 kHz switchable magnetic field of up to 1.5 T across the sample combining ellipsometry and Kerr spectroscopy measurements in an unprecedented spectral range. This form of generalized ellipsometry enables users to address diagonal and off-diagonal components of the dielectric tensor within one measurement. Pump-probe measurements enable users to study the dynamic behaviour of the dielectric tensor in order to resolve the time-domain phenomena in the femto to 100 ns range.

  • 9.
    Farkas, B.
    et al.
    Univ Szeged, Dept Opt & Quantum Elect, Szeged, Hungary; ELI HU Nonprofit Ltd, Szeged, Hungary.
    Heszler, P.
    Univ Szeged, Hungarian Acad Sci, Res Grp Laser Phys, Szeged, Hungary.
    Budai, J.
    Univ Szeged, Dept Opt & Quantum Elect, Szeged, Hungary.
    Oszko, A.
    Univ Szeged, Hungarian Acad Sci, React Kinet Res Grp, Szeged, Hungary.
    Ottosson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Geretovszky, Zs.
    Univ Szeged, Dept Opt & Quantum Elect, Szeged, Hungary.
    Optical, compositional and structural properties of pulsed laser deposited nitrogen-doped Titanium-dioxide2018In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 433, p. 149-154Article in journal (Refereed)
    Abstract [en]

    N-doped TiO2 thin films were prepared using pulsed laser deposition by ablating metallic Ti target with pulses of 248 nm wavelength, at 330 °C substrate temperature in reactive atmospheres of N2/O2 gas mixtures. These films were characterized by spectroscopic ellipsometry, X-ray photoelectron spectroscopy and X-ray diffraction. Optical properties are presented as a function of the N2 content in the processing gas mixture and correlated to nitrogen incorporation into the deposited layers. The optical band gap values decreased with increasing N concentration in the films, while a monotonically increasing tendency and a maximum can be observed in case of extinction coefficient and refractive index, respectively. It is also shown that the amount of substitutional N can be increased up to 7.7 at.%, but the higher dopant concentration inhibits the crystallization of the samples.

  • 10.
    Fredriksson, Wendy
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Malmgren, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gorgoi, Mihaela
    Helmholtz Zentrum Berlin Germany.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Full depth profile of passive films on 316L stainless steel based on high resolution HAXPES in combination with ARXPS2012In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 258, no 15, p. 5790-5797Article in journal (Refereed)
    Abstract [en]

    Depth profiles of the passive films on stainless steel were based on analysis with the non-destructive hard X-ray photoelectron spectroscopy (HAXPES) technique in combination with the angular resolved X-ray photoelectron spectroscopy (ARXPS). The analysis depth with ARXPS is within the passive film thickness, while the HAXPES technique uses higher excitation energies (between 2 and 12 keV) also non-destructively probing the chemical content underneath the film. Depth profiles were done within and underneath the passive film of 316L polarized in acidic solution. The passive film thickness was estimated to 2.6 nm for a sample that was polarized at 0.6 V and the main component in the passive film is, as expected, chromium. From the high resolution HAXPES spectra we suggest chromium in three different oxidation states present. Also for iron three oxides were detected. Gradients of chromium and iron concentrations and oxidation states within the film and an enrichment of nickel within a 0.5 nm layer directly underneath the passive film are some of the results discussed. 

  • 11.
    Greczynski, G.
    et al.
    Linkoping Univ, IFM, Dept Phys, Thin Film Phys Div, SE-58183 Linkoping, Sweden..
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Hultman, L.
    Linkoping Univ, IFM, Dept Phys, Thin Film Phys Div, SE-58183 Linkoping, Sweden..
    Reference binding energies of transition metal carbides by core-level x-ray photoelectron spectroscopy free from Ar+ etching artefacts2018In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 436, p. 102-110Article in journal (Refereed)
    Abstract [en]

    We report x-ray photoelectron spectroscopy (XPS) core level binding energies (BE's) for the widely-applicable groups IVb-VIb transition metal carbides (TMCs) TiC, VC, CrC, ZrC, NbC, MoC, HfC, TaC, and WC. Thin film samples are grown in the same deposition system, by dc magnetron co-sputtering from graphite and respective elemental metal targets in Ar atmosphere. To remove surface contaminations resulting from exposure to air during sample transfer from the growth chamber into the XPS system, layers are either (i) Ar+ ion-etched or (ii) UHV-annealed in situ prior to XPS analyses. High resolution XPS spectra reveal that even gentle etching affects the shape of core level signals, as well as BE values, which are systematically offset by 0.2-0.5 eV towards lower BE. These destructive effects of Ar+ ion etch become more pronounced with increasing the metal atom mass due to an increasing carbon-to-metal sputter yield ratio. Systematic analysis reveals that for each row in the periodic table (3d, 4d, and 5d) C 1s BE increases from left to right indicative of a decreased charge transfer from TM to C atoms, hence bond weakening. Moreover, C 1s BE decreases linearly with increasing carbide/metal melting point ratio. Spectra reported here, acquired from a consistent set of samples in the same instrument, should serve as a reference for true deconvolution of complex XPS cases, including multinary carbides, nitrides, and carbonitrides.

  • 12.
    Greczynski, G.
    et al.
    Linkoping Univ, Dept Phys IFM, Thin Film Phys Div, SE-58183 Linkoping, Sweden..
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Lu, J.
    Linkoping Univ, Dept Phys IFM, Thin Film Phys Div, SE-58183 Linkoping, Sweden..
    Hultman, L.
    Linkoping Univ, Dept Phys IFM, Thin Film Phys Div, SE-58183 Linkoping, Sweden..
    Core-level spectra and binding energies of transition metal nitrides by non-destructive x-ray photoelectron spectroscopy through capping layers2017In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 396, p. 347-358Article in journal (Refereed)
    Abstract [en]

    We present the first measurements of x-ray photoelectron spectroscopy (XPS) core level binding energies (BE: s) for the widely-applicable group IVb-VIb polycrystalline transition metal nitrides (TMN's) TiN, VN, CrN, ZrN, NbN, MoN, HfN, TaN, and WN as well as AlN and SiN, which are common components in the TMN-based alloy systems. Nitride thin film samples were grown at 400.degrees C by reactive dc magnetron sputtering from elemental targets in Ar/ N-2 atmosphere. For XPS measurements, layers are either (i) Ar+ ion-etched to remove surface oxides resulting from the air exposure during sample transfer from the growth chamber into the XPS system, or (ii) in situ capped with a few nm thick Cr or W overlayers in the deposition system prior to air-exposure and loading into the XPS instrument. Film elemental composition and phase content is thoroughly characterized with time-of-flight elastic recoil detection analysis (ToF(-) ERDA), Rutherford backscattering spectrometry (RBS), and x-ray diffraction. High energy resolution core level XPS spectra acquired with monochromatic Al K alpha radiation on the ISO-calibrated instrument reveal that even mild etching conditions result in the formation of a nitrogen-deficient surface layer that substantially affects the extracted binding energy values. These spectra-modifying effects of Ar+ ion bombardment increase with increasing the metal atom mass due to an increasing nitrogen-to-metal sputter yield ratio. The superior quality of the XPS spectra obtained in a non-destructive way from capped TMN films is evident from that numerous metal peaks, including Ti 2p, V 2p, Zr 3d, and Hf 4f, exhibit pronounced satellite features, in agreement with previously published spectra from layers grown and analyzed in situ. In addition, the N/ metal concentration ratios are found to be 25-90% higher than those obtained from the corresponding ion-etched surfaces, and in most cases agree very well with the RBS and ToF-E ERDA values. The N 1 s BE: s extracted from capped TMN films, thus characteristic of a native surface, show a systematic trend, which contrasts with the large BE spread of literature "reference" values. Hence, non-destructive core level XPS employing capping layers provides an opportunity to obtain high-quality spectra, characteristic of virgin in situ grown and analyzed TMN films, although with larger versatility, and allows for extracting core level BE values that are more reliable than those obtained from sputter-cleaned N-deficient surfaces. Results presented here, recorded from a consistent set of binary TMN's grown under the same conditions and analyzed in the same instrument, provide a useful reference for future XPS studies of multinary materials systems allowing for true deconvolution of complex core level spectra.

  • 13.
    Göthelid, M.
    et al.
    KTH, MNF, SCI, Mat Fys, S-16440 Kista, Sweden..
    Hosseinpour, S.
    Univ Erlangen Nurnberg, Inst Particle Technol LFG, Cauerstr 4, D-91058 Erlangen, Germany..
    Ahmadi, Sareh
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Leygraf, C.
    KTH, Dept Chem, Div Surface & Corros Sci, S-10044 Stockholm, Sweden..
    Johnson, C. M.
    KTH, Dept Chem, Div Surface & Corros Sci, S-10044 Stockholm, Sweden..
    Hexane selenol dissociation on Cu: The protective role of oxide and water2017In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 423, p. 716-720Article in journal (Refereed)
    Abstract [en]

    Hexane selenol (CH3(CH2)(5)SeH) was adsorbed from gas phase in ultra-high vacuum on polycrystalline Cu and studied with synchrotron radiation based photoelectron spectroscopy (PES) and Near edge X-ray absorption fine structure spectroscopy (NEXAFS). Adsorption was done on a bare copper surface at room temperature (RT), on a thin oxide on Cu at room temperature, and on a thin layer of water on Cu at 140 K.

  • 14. Hellwig, M. Ay. O
    et al.
    Becker, H. W.
    Hjörvarsson, Björgvin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Materials Science, Materials Physics.
    Zabel, H.
    Oxidation of epitaxial Y(0001) films2008In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 254, no 10, p. 3184-3190Article in journal (Refereed)
    Abstract [en]

    We have investigated the oxidation behavior of MBE grown epitaxial Y(0 0 0 1)/Nb(1 1 0) films on sapphire (11 (2) over bar0) substrates at elevated temperatures under atmospheric conditions with a combination of experimental methods. At room temperature X-ray diffraction (XRD) reveals the formation of a 25 A thick YOxHx layer at the surface, while simultaneously oxide growth proceeds along defect lines normal to the film plane, resulting in the formation of a single crystalline cubic Y2O3 (2 2 2) phase. Furthermore, nuclear resonance analysis (NRA) reveals that hydrogen penetrates into the sample and transforms the entire Y film into the hydride YH2 phase. Additional annealing in air leads to further oxidation radially out from the already existing oxide channels. Finally material transport during oxidation results in the formation of conically shaped oxide precipitations at the surface above the oxide channels as observed by atomic force microscopy (AFM).

  • 15.
    Heszler, P.
    et al.
    Research Group of Laser Physics of the Hungarian Academy of Sciences, University of Szeged.
    Landström, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Granqvist, Claes G.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Laser-Induced Synthesis of Nanostructured Thin Films2007In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 253, no 19, p. 8292-8299Article in journal (Refereed)
    Abstract [en]

    We present a number of important characteristics of laser techniques for preparation of nanostructured thin films with foci on laser ablation (LA) and laser-assisted chemical vapor decomposition (LCVD). Size-related features and structures of the deposited layers are associated with process parameters. Whenever possible, the performance of the deposits is compared to that of films prepared by other methods (e.g., physical vapor synthesis such as gas deposition, sputtering, etc.). The LA and LCVD methods allow a wide variety of materials to be prepared. A number of promising applications emerge when one combines this versatility with the potential for making certain types of nanostructured layers. These possibilities are also discussed.

  • 16.
    Högström, Jonas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Fredriksson, Wendy
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Olsson, Claes-O. A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Cation profiling of passive films on stainless steel formed in sulphuric and acetic acid by deconvolution of angle-resolved X-ray photoelectron spectra2013In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 284, p. 700-714Article in journal (Refereed)
    Abstract [en]

    An approach for determining depth gradients of metal-ion concentrations in passive films on stainlesssteel using angle-resolved X-ray photoelectron spectroscopy (ARXPS) is described. The iterative method,which is based on analyses of the oxidised metal peaks, provides increased precision and hence allowsfaster ARXPS measurements to be carried out. The method was used to determine the concentrationdepth profiles for molybdenum, iron and chromium in passive films on 316L/EN 1.4432 stainless steelsamples oxidised in 0.5 M H2SO4 and acetic acid diluted with 0.02 M Na2B4O7 · 10H2O and 1 M H2O,respectively. The molybdenum concentration in the film is pin-pointed to the oxide/metal interface andthe films also contained an iron-ion-enriched surface layer and a chromium-ion-dominated middle layer.Although films of similar composition and thickness (i.e., about 2 nm) were formed in the two electrolytes,the corrosion currents were found to be three orders of magnitude larger in the acetic acid solution.The differences in the layer composition, found for the two electrolytes as well as different oxidationconditions, can be explained based on the oxidation potentials of the metals and the dissolution rates ofthe different metal ions.

  • 17.
    Intarasiri, Saweat
    et al.
    Institute for Science and Technology Research and Development, Chiang Mai University.
    Hallén, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Lu, Jun
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Jensen, Jens
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Bertilsson, K.
    Mittuniversitetet.
    Wolborski, M.
    KTH.
    Singkarat, S.
    FNRF, Department of Physics, Faculty of Science, Chiang Mai University.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Crystalline quality of 3C-SiC formed by high-fluence C+-implanted Si2007In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 253, no 11, p. 4836-4842Article in journal (Refereed)
    Abstract [en]

    Carbon ions at 40 keV were implanted into (1 0 0) high-purity p-type silicon wafers at 400 °C to a fluence of 6.5 × 1017 ions/cm2. Subsequent thermal annealing of the implanted samples was performed in a diffusion furnace at atmospheric pressure with inert nitrogen ambient at 1100 °C. Time-of-flight energy elastic recoil detection analysis (ToF-E ERDA) was used to investigate depth distributions of the implanted ions. Infrared transmittance (IR) and Raman scattering measurements were used to characterize the formation of SiC in the implanted Si substrate. X-ray diffraction analysis (XRD) was used to characterize the crystalline quality in the surface layer of the sample. The formation of 3C-SiC and its crystalline structure obtained from the above mentioned techniques was finally confirmed by transmission electron microscopy (TEM). The results show that 3C-SiC is directly formed during implantation, and that the subsequent high-temperature annealing enhances the quality of the poly-crystalline SiC.

  • 18.
    Kuzmin, Mikhail
    et al.
    Tampere Univ Technol, Optoelect Res Ctr, Surface Sci Lab, POB 692, FI-33101 Tampere, Finland.;Russian Acad Sci, Ioffe Phys Tech Inst, 26 Polytekhnicheskaya, St Petersburg 194021, Russia..
    Lahtonen, Kimmo
    Tampere Univ Technol, Optoelect Res Ctr, Surface Sci Lab, POB 692, FI-33101 Tampere, Finland..
    Vuori, Leena
    Tampere Univ Technol, Optoelect Res Ctr, Surface Sci Lab, POB 692, FI-33101 Tampere, Finland..
    Sánchez-de-Armas, Rocío
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Hirsimäki, Mika
    Tampere Univ Technol, Optoelect Res Ctr, Surface Sci Lab, POB 692, FI-33101 Tampere, Finland..
    Valden, Mika
    Tampere Univ Technol, Optoelect Res Ctr, Surface Sci Lab, POB 692, FI-33101 Tampere, Finland..
    Investigation of the structural anisotropy in a self-assembling glycinate layer on Cu(100) by scanning tunneling microscopy and density functional theory calculations2017In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 409, p. 111-116Article in journal (Refereed)
    Abstract [en]

    Self-assembling organic molecule-metal interfaces exhibiting free-electron like (FEL) states offers an attractive bottom-up approach to fabricating materials for molecular electronics. Accomplishing this, however, requires detailed understanding of the fundamental driving mechanisms behind the self assembly process. For instance, it is still unresolved as to why the adsorption of glycine ([NH2(CH2)COOH) on isotropic Cu(100) single crystal surface leads, via deprotonation and self-assembly, to a glycinate ([NH2(CH2)COO-]) layer that exhibits anisotropic FEL behavior. Here, we report on bias-dependent scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations for glycine adsorption on Cu(100) single crystal surface. We find that after physical vapor deposition (PVD) of glycine on Cu(100), glycinate self-assembles into an overlayer exhibiting c(2 x 4) and p(2 x 4) symmetries with non-identical adsorption sites. Our findings underscore the intricacy of electrical conductivity in nanomolecular organic overlayers and the critical role the structural anisotropy at molecule-metal interface plays in the fabrication of materials for molecular electronics.

  • 19. Lauridsen, J.
    et al.
    Nedfors, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jensen, J.
    Eklund, P.
    Hultman, L.
    Ti-B-C nanocomposite coatings deposited by magnetron sputtering2012In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 258, no 24, p. 9907-9912Article in journal (Refereed)
    Abstract [en]

    Ti-B-C nanocomposite coatings with a B content of 8-17 at.% have been deposited by magnetron sputtering from B4C, Ti, and C targets. X-ray diffraction, photoelectron spectroscopy, and electron microscopy show that the coatings consist of nanocrystalline (nc) TiC: B embedded in a matrix of amorphous (a) C, BCx, TiOx and BOx. The fraction of amorphous phase scales with the Ti concentration, where the matrix predominantly consists of free C with some BCx in coatings with a C/Ti ratio > 1, while the matrix predominantly consists of BCx with some free C in coatings with a C/Ti ratio < 1. nc-TiC:B/a-BCx/a-C coatings with low amount of free C exhibit a contact resistance comparable to the contact resistance of an Ag sputtered coating at loads of similar to 1 N against an Au probe, despite the O content of similar to 16 at.%.

  • 20.
    Lewin, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Empa, Lab Nanoscale Mat Sci, Uberlandstr 129, CH-8600 Dubendorf, Switzerland.
    Counsell, Jonathan
    Kratos Analyt Ltd, Trafford Wharf Rd, Manchester M17 1G, Lancs, England.
    Patscheider, Jörg
    Empa, Lab Nanoscale Mat Sci, Uberlandstr 129, CH-8600 Dubendorf, Switzerland;Evatec AG, Trubbach, Switzerland.
    Spectral artefacts post sputter-etching and how to cope with them - A case study of XPS on nitride-based coatings using monoatomic and cluster ion beams2018In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 442, p. 487-500Article in journal (Refereed)
    Abstract [en]

    The issue of artefacts due to sputter-etching has been investigated for a group of AlN-based thin film materials with varying thermodynamical stability. Stability of the materials was controlled by alloying AlN with the group 14 elements Si, Ge or Sn in two different concentrations. The coatings were sputter-etched with monoatomic Ar+ with energies between 0.2 and 4.0 keV to study the sensitivity of the materials for sputter damage. The use of Ar-n(+) clusters to remove an oxidised surface layer was also evaluated for a selected sample. The spectra were compared to pristine spectra obtained after in-vacuo sample transfer from the synthesis chamber to the analysis instrument. It was found that the all samples were affected by high energy (4 keV) Ar+ ions to varying degrees. The determining factors for the amount of observed damage were found to be the materials' enthalpy of formation, where a threshold value seems to exist at approximately -1.25 eV/atom (similar to-120 kJ/mol atoms). For each sample, the observed amount of damage was found to have a linear dependence to the energy deposited by the ion beam per volume removed material. Despite the occurrence of sputter-damage in all samples, etching settings that result in almost artefact-free spectral data were found; using either very low energy (i.e. 200 eV) monoatomic ions, or an appropriate combination of ion cluster size and energy. The present study underlines that analysis post sputter-etching must be carried out with an awareness of possible sputter-induced artefacts.

  • 21.
    Lilja, Mirjam
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Butt, Umer
    Sandvik Coromant.
    Bjöörn, Dorota
    Sandvik Coromant.
    Shen, Zhijian
    Nucleation and growth of hydroxyapatite on arc-deposited TiO2surfaces studied by quartz crystal microbalance with dissipation2013In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 284, p. 1-6Article in journal (Refereed)
    Abstract [en]

    Understanding of nucleation and growth kinetics of biomimetically deposited hydroxyapatite (HA) oncrystalline TiO2surfaces is important with respect to the application and performance of HA as functionalimplant coatings. Arc-evaporation was used to deposit TiO2coatings dominated by anatase phase, rutilephase or their mixtures. Subsequent formation of HA from phosphate buffered saline solution (PBS) wasinvestigated in real-time using in situ quartz crystal microbalance with dissipation technique (QCM-D). Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to characterize thepresence, morphology and crystal structure of TiO2coatings and the formed HA. Increasing temperature ofthe PBS, increasing flow rate and applying a higher ion concentration in solution were found to accelerateHA nucleation process and hence affect growth kinetics. Lower PBS temperature resulted in the formationof HA coatings with flake-like morphology and increasing HA porosity. All TiO2coatings under studyenabled HA formation at body temperature, while in contrast Ti reference surfaces only supported HAnucleation and growth at elevated temperatures. QCM-D technique is a powerful tool for studying theimpact of process parameters during biomimetic coating deposition on coating structure evolution in realtime and provides valuable information for understanding, optimizing as well as tailoring the biomimeticHA growth processes.

  • 22.
    Lindahl, Carl
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Effect of strontium ions on the early formation of biomimetic apatite on single crystalline rutile2013In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 266, p. 199-204Article in journal (Refereed)
    Abstract [en]

    Single crystalline rutile is a good model to investigate the growth mechanism of hydroxyapatite on bioactive Ti surfaces. Previous studies have shown the difference on different crystalline rutile faces in the early stage and during the growth of HAp crystals from simulated body fluids. It is known that the biological apatite crystal is an ion-substituted apatite. Ion substitution will influence the HAp crystal growth and morphology. In the present study, the effect of strontium ions on the adsorption of Ca and phosphate ions on three different faces of single crystalline rutile substrates has been investigated. The ion adsorption is the crucial step in the nucleation of HAp crystals on specific surfaces. Single crystalline rutile surfaces ((1 1 0), (1 0 0) and (0 0 1)) were soaked in phosphate buffer solutions containing calcium and strontium ions for different time periods. The results showed that the adsorption of Sr, Ca and P is faster on the (1 1 0) surface than on the (1 0 0) and (0 0 1) surfaces. Almost same amount of Sr ion was adsorbed on the surfaces compared to the adsorption of Ca ion. Strontium ion influenced the biological apatite formation in the early stage in this study.

  • 23.
    Lindahl, Carl
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Xia, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Snis, Anders
    Arcam AB, Sweden.
    Lausmaa, Jukka
    Palmquist, Anders
    Department of Biomaterials, Sahlgrenska Academy at the University of Gothenburg, Gothenburg.
    Biomimetic calcium phosphate coating of additively manufactured porous CoCr implants2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 353, p. 40-47Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to study the feasibility to use a biomimetic method to prepare biomimetic hydroxyapatite (HA) coatings on CoCr substrates with short soaking times and to characterize the properties of such coatings. A second objective was to investigate if the coatings could be applied to porous CoCr implants manufactured by electron beam melting (EBM). The coating was prepared by immersing the pretreated CoCr substrates and EBM implants into the phosphate-buffered solution with Ca2+ in sealed plastic bottles, kept at 60 degrees C for 3 days. The formed coating was partially crystalline, slightly calcium deficient and composed of plate-like crystallites forming roundish flowers in the size range of 300-500 nm. Cross-section imaging showed a thickness of 300-500 nm. In addition, dissolution tests in Tris-HCl up to 28 days showed that a substantial amount of the coating had dissolved, however, undergoing only minor morphological changes. A uniform coating was formed within the porous network of the additive manufactured implants having similar thickness and morphology as for the flat samples. In conclusion, the present coating procedure allows coatings to be formed on CoCr and could be used for complex shaped, porous implants made by additive manufacturing.

  • 24.
    Magnuson, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics II.
    Butorin, Sergei
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics II.
    Werme, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics II.
    Nordgren, Joseph
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics II.
    Ivanov, Kiril
    Guo, Jinghua
    Shuh, David
    Uranium oxides investigated by X-ray absorption and emission spectroscopies2006In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, no 15, p. 5615-5618Article in journal (Refereed)
    Abstract [en]

    X-ray absorption and resonant X-ray emission measurements at the O 1s edge of the uranium oxides UO2, U3O8 and UO3 are presented. The spectral shapes of the O Kα X-ray emission spectra of UO3 exhibit significant excitation energy dependence, from an asymmetric to a symmetric form, which differs from those of UO2 and U3O8. This energy dependence is attributed to a significant difference in the oxygen–uranium hybridization between two different sites in the crystal structure of UO3. The spectral shapes of UO2 and U3O8 are also found to be different but without significant energy dependence. The experimental spectra of the valence and conduction bands of the uranium oxides are compared to the results of electronic structure calculations available in the literature.

  • 25. Nilsson, Sara
    et al.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Robinson, Nathaniel D.
    Electrochemical quartz crystal microbalance study of polyelectrolyte film growth under anodic conditions2013In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 280, p. 783-790Article in journal (Refereed)
    Abstract [en]

    Coating hard materials such as Pt with soft polymers like poly-l-lysine is a well-established technique for increasing electrode biocompatibility. We have combined quartz crystal microgravimetry with dissipation with electrochemistry (EQCM-D) to study the deposition of PLL onto Pt electrodes under anodic potentials. Our results confirm the change in film growth over time previously reported by others. However, the dissipation data suggest that, after the short initial phase of the process, the rigidity of the film increases with time, rather than decreasing, as previously proposed. In addition to these results, we discuss how gas evolution from water electrolysis and Pt etching in electrolytes containing Cl- affect EQCM-D measurements, how to recognize these effects, and how to reduce them. Despite the challenges of using Pt as an anode in this system, we demonstrate that the various electrochemical processes can be understood and that PLL coatings can be successfully electrodeposited. 

  • 26.
    Nygren, Kristian
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Andersson, Matilda
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Högström, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Fredriksson, Wendy
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Influence of deposition temperature and amorphous carbon on microstructure and oxidation resistance of magnetron sputtered nanocomposite Cr-C films2014In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 305, p. 143-153Article in journal (Refereed)
    Abstract [en]

    It is known that mechanical and tribological properties of transition metal carbide films can be tailored by adding an amorphous carbon (a-C) phase, thus making them nanocomposites. This paper addresses deposition, microstructure, and for the first time oxidation resistance of magnetron sputtered nanocomposite Cr C/a-C films with emphasis on studies of both phases. By varying the deposition temperature between 20 and 700 C and alternating the film composition, it was possible to deposit amorphous, nanocomposite, and crystalline Cr C films containing about 70% C and 30% Cr, or 40% C and 60% Cr. The films deposited at temperatures below 300 degrees C were X-ray amorphous and 500 C was required to grow crystalline phases. Chronoamperometric polarization at +0.6 V vs. Ag/AgCl(sat. KG) in hot 1 mM H-2 SO4 resulted in oxidation of Cr C, yielding Cr203 and C, as well as oxidation of C. The oxidation resistance is shown to depend on the deposition temperature and the presence of the a-C phase. Physical characterization of film surfaces show that very thin C/Cr2O3/Cr C layers develop on the present material, which can be used to improve the oxidation resistance of, e.g. stainless steel electrodes. (C) 2014 Elsevier B.V. All rights reserved.

  • 27.
    Ouyang, Tianhong
    et al.
    Shandong Univ, Minist Educ, Key Lab Liquid Solid Struct Evolut & Proc Mat, Jinan, Shandong, Peoples R China.;Shandong Univ, Suzhou Inst, Jinan, Shandong, Peoples R China..
    Qian, Zhao
    Shandong Univ, Minist Educ, Key Lab Liquid Solid Struct Evolut & Proc Mat, Jinan, Shandong, Peoples R China.;Shandong Univ, Suzhou Inst, Jinan, Shandong, Peoples R China..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Liu, Xiangfa
    Shandong Univ, Minist Educ, Key Lab Liquid Solid Struct Evolut & Proc Mat, Jinan, Shandong, Peoples R China.;Shandong Univ, Suzhou Inst, Jinan, Shandong, Peoples R China..
    First-principles investigation of CO adsorption on pristine, C-doped and N-vacancy defected hexagonal AlN nanosheets2018In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 439, p. 196-201Article in journal (Refereed)
    Abstract [en]

    The optimized atomic structures, energetics and electronic structures of toxic gas CO adsorption systems on pristine, C-doped and N-vacancy defected h-AlN nanosheets respectively have been investigated using Density functional theory (DFT-D2 method) to explore their potential gas detection or sensing capabilities. It is found that both the C-doping and the N-vacancy defect improve the CO adsorption energies of AlN nanosheet (from pure -3.847 eV to -5.192 eV and -4.959 eV). The absolute value of the system band gap change induced by adsorption of CO can be scaled up to 2.558 eV or 1.296 eV after C-doping or N-vacancy design respectively, which is evidently larger than the value of 0.350 eV for pristine material and will benefit the robustness of electronic signals in potential gas detection. Charge transfer mechanisms between CO and the AlN nanosheet have been presented by the Bader charge and differential charge density analysis to explore the deep origin of the underlying electronic structure changes. This theoretical study is proposed to predict and understand the CO adsorption properties of the pristine and defected h-AlN nanosheets and would help to guide experimentalists to develop better AlN-based two-dimensional materials for efficient gas detection or sensing applications in the future.

  • 28.
    Pasti, Igor A.
    et al.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia..
    Jovanovic, Aleksandar
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia.;CEST Kompetenzzentrum Elektrochem Oberfiachentecn, Viktor Kaplan Str 2,Sect A, A-2700 Wiener Neustadt, Austria..
    Dobrota, Ana S.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia..
    Mentus, Slavko V.
    Univ Belgrade, Fac Phys Chem, Studentski Trg 12-16, Belgrade 11158, Serbia.;Serbian Acad Arts & Sci, Knez Mihajlova 35, Belgrade 11000, Serbia..
    Johansson, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Sch Ind Engn & Management, Dept Mat Sci & Engn, Stockholm, Sweden..
    Skorodumova, Natalia V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. KTH Royal Inst Technol, Sch Ind Engn & Management, Dept Mat Sci & Engn, Stockholm, Sweden..
    Atomic adsorption on pristine graphene along the Periodic Table of Elements - From PBE to non-local functionals2018In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 436, p. 433-440Article in journal (Refereed)
    Abstract [en]

    The understanding of atomic adsorption on graphene is of high importance for many advanced technologies. Here we present a complete database of the atomic adsorption energies for the elements of the Periodic Table up to the atomic number 86 (excluding lanthanides) on pristine graphene. The energies have been calculated using the projector augmented wave (PAW) method with PBE, long-range dispersion interaction corrected PBE (PBE+D2, PBE+D3) as well as non-local vdW-DF2 approach. The inclusion of dispersion interactions leads to an exothermic adsorption for all the investigated elements. Dispersion interactions are found to be of particular importance for the adsorption of low atomic weight earth alkaline metals, coinage and s-metals (11th and 12th groups), high atomic weight p-elements and noble gases. We discuss the observed adsorption trends along the groups and rows of the Periodic Table as well some computational aspects of modelling atomic adsorption on graphene.

  • 29.
    Piancastelli, Maria Novella
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Bao, Zhuo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Hennies, F.
    Travnikova, Oksana
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Céolin, Denis
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Kampen, T.
    Horn, K.
    Electronic and Geometric Structure of Methyl Oxirane Adsorbed on Si (100) 2 × 12007In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 254, no 1, p. 108-112Article in journal (Refereed)
    Abstract [en]

    Electronic and geometric properties of the adsorbate–substrate complex formed upon adsorption of methyl oxirane on Si(1 0 0)2 × 1 at room temperature is reported, obtained with synchrotron radiation-induced valence and core-level photoemission. A ring-opening reaction is demonstrated to occur, followed by a five-membered ring formation involving two of the Si surface atoms bound to a surface dimer. Core-level photoemission spectra support the ring-opening reaction and the SiO and SiC bond formation, while from the valence spectra a more extended molecular fragmentation can be ruled out. We discuss the most likely geometry of the five-membered ring.

  • 30. Rashid, A
    et al.
    Landström, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Brodoceanu, D
    Piglmayer, K
    Lamp-assisted CVD of carbon micro/nano-structures using metal catalysts and CH2I2 precursor2009In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 255, no 10, p. 5368-5372Article in journal (Refereed)
    Abstract [en]

    Carbon micro/nanofibers and nanotubes were deposited via chemical vapor deposition (CVD) using CH2I2 precursor and different metal catalysts (Pd, Ni, Fe, Co and Mn) on Si (1 0 0) substrates. A versatile and low-cost IR lamp technique is employed to induce the deposition process. With this method carbon features could be obtained already at temperatures much lower than with common techniques. Palladium metal was deposited by laser-assisted CVD from a liquid solution of the ammine complex and the 3d metals by thermal evaporation. Large-scale periodicity of nano-sized metal catalysts, and subsequently of carbon deposits was obtained by using monolayers of polystyrene microspheres as mask. The carbon structures were analyzed by SEM and micro-Raman spectroscopy.

  • 31. Schaefer, A.
    et al.
    Ragazzon, Davide
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Walle, L. E.
    Farstad, M. H.
    Wichmann, A.
    Baeumer, M.
    Borg, A.
    Sandell, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Controlled modification of nanoporous gold: Chemical vapor deposition of TiO2 in ultrahigh vacuum2013In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 282, p. 439-443Article in journal (Refereed)
    Abstract [en]

    TiO2 has been deposited in the first 400 nm of a nanoporous gold (NPG) structure using metal organic chemical vapor deposition with titanium-tetraisopropoxide as single source precursor in ultra high vacuum. The NPG has been pretreated by ozone to clean and stabilize the structure for deposition. The deposited oxide stabilizes the porous structure, otherwise prone to coarsening at elevated temperatures, up to 300 degrees C. The study combines the controlled sample preparation with a functional test of the prepared catalyst under real conditions in a continuous gas flow reactor. The catalytic activity of the loaded NPG at 60 degrees C for CO oxidation is found to be superior to unloaded as-prepared NPG.

  • 32.
    Schulte, Karina
    et al.
    MAX-Lab, Lund University.
    Vinogradov, Nikolay
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    May Ling, Ng
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Nils, Mårtensson
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Alexei, Preobrajenski
    MAX-Lab, Lund University.
    Bandgap formation in graphene on Ir(1 1 1) through oxidation2013In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 267, p. 74-76Article in journal (Refereed)
    Abstract [en]

    A graphene monolayer on single crystal Ir(111) has been studied using angle-resolved photoemission spectroscopy (ARPES) before and after exposure to atomic oxygen. With increasing oxygen coverage the Dirac cone, centered on the K-point of the Brillouin zone, broadens and finally transforms to a parabolic rather than linear feature, introducing a pronounced energy bandgap at the Fermi level. The opening of a bandgap of at least 0.35 eV was observed at the oxygen exposure close to the saturation coverage.

  • 33. Serra, R.
    et al.
    Oliveira, V.
    Oliveira, J. C.
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Vilar, R.
    Cavaleiro, A.
    Large-area homogeneous periodic surface structures generated on the surface sputtered boron carbide thin films by femtosecond laser processing2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 331, p. 161-169Article in journal (Refereed)
    Abstract [en]

    Amorphous and crystalline sputtered boron carbide thin films have a very high hardness even surpassing that of bulk crystalline boron carbide (approximate to 41 GPa). However, magnetron sputtered B-C films have high friction coefficients (C.o.F) which limit their industrial application. Nanopatterning of materials surfaces has been proposed as a solution to decrease the C.o.F. The contact area of the nanopatterned surfaces is decreased due to the nanometre size of the asperities which results in a significant reduction of adhesion and friction. In the present work, the surface of amorphous and polycrystalline B-C thin films deposited by magnetron sputtering was nanopatterned using infrared femtosecond laser radiation. Successive parallel laser tracks 10 mu m apart were overlapped in order to obtain a processed area of about 3 mm(2). Sinusoidal-like undulations with the same spatial period as the laser tracks were formed on the surface of the amorphous boron carbide films after laser processing. The undulations amplitude increases with increasing laser fluence. The formation of undulations with a 10 mu m period was also observed on the surface of the crystalline boron carbide film processed with a pulse energy of 72 mu J. The amplitude of the undulations is about 10 times higher than in the amorphous films processed at the same pulse energy due to the higher roughness of the films and consequent increase in laser radiation absorption. LIPSS formation on the surface of the films was achieved for the three B-C films under study. However, LIPSS are formed under different circumstances. Processing of the amorphous films at low fluence (72 mu J) results in LIPSS formation only on localized spots on the film surface. LIPSS formation was also observed on the top of the undulations formed after laser processing with 78 mu J of the amorphous film deposited at 800 degrees C. Finally, large-area homogeneous LIPSS coverage of the boron carbide crystalline films surface was achieved within a large range of laser fluences although holes are also formed at higher laser fluences.

  • 34. Sorar, I.
    et al.
    Pehlivan, E.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, C.-G.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochromism of DC Magnetron-Sputtered TiO2: Role of Film Thickness2014In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 318, p. 24-27Article in journal (Refereed)
  • 35.
    Sorar, Idris
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Pehlivan, Esat
    ChromoGenics AB, Uppsala.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Electrochromism of DC magnetron sputtered TiO2: Role of film thickness2014In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 318, p. 24-27Article in journal (Refereed)
    Abstract [en]

    Titanium dioxide films were prepared by reactive DC magnetron sputtering and the role of the film thick-ness d on the electrochromism was analyzed for 100 < d < 400 nm. The best properties were obtainedfor the thickest films, which yielded a mid-luminous transmittance modulation of 58% and a corre-sponding coloration efficiency of 26.3 cm2/C. The films were amorphous according to X-ray diffractionmeasurements and showed traces of adsorbed water as revealed by infrared spectroscopy.

  • 36.
    Sundberg, Jill
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Gorgoi, Mihaela
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Understanding the effects of sputter damage in W–S thin films by HAXPES2014In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 305, p. 203-213Article in journal (Refereed)
    Abstract [en]

    WS2 is an excellent solid lubricant in dry conditions, and can be applied as thin films. The analysis of WS2 and WS2-based films by x-ray photoelectron spectroscopy (XPS) can be challenging, due to contaminationand oxidized material on the surface. The investigations have traditionally therefore included sputter etching by ion bombardment, which however leads to changes of the remaining material. In this study, hard x-ray photoelectron spectroscopy (HAXPES) has been used to study W–S films deposited bymagnetron sputtering. High-resolution reference measurements for crystalline WS2 and metallic W are also presented. The W–S films were analyzed before and after sputter cleaning by Ar+ ion bombardment, using photon energies of 3 and 6 keV. The as-deposited films were found to consist mainly of a WSx phase,similar to WS2 but with a broader range of chemical states. It is shown that ion bombardment of the surface not only removes the outermost oxidized material, but also leads to preferential sputtering of sulfur and the formation of metallic tungsten. The results are of strong interest for the analysis of WS2-based materials, as they demonstrate that spectra from sputter-cleaned films include effects of sputter damage,and may not be representative of the original sample.

  • 37. Tatar, B.
    et al.
    Gokdemir, F. P.
    Pehlivan, Esat
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Urgen, M.
    The influence of Er3+ doping on the structural and optical properties of CeO2 thin films grown by PED2013In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 285, no Part B, p. 409-416Article in journal (Refereed)
    Abstract [en]

    Erbium doped CeO2 thin films were deposited on both Corning glass substrates and indium doped tin oxide (ITO) coated glass substrates by pulsed e-beam deposition (PED) method at room temperature. Structural features of Er doped CeO2 thin films were studied with X-ray diffraction (XRD) and micro-Raman spectra. The XRD patterns of all films showed polycrystalline nature and cubic crystalline structure. Raman active peaks for both undoped CeO2 and Er doped CeO2 films were determined at similar to 465 cm(-1). The Raman shift observed in this study can also be assigned to Raman active modes of CeO2 that are shifted from the original position due to different doping concentration. The optical properties of CeO2 films and Er doped CeO2 films, which were determined from transmittance and reflectance measurements at room temperature, were very similar in character. The refractive indices and extinction coefficients, which were calculated from 3.5 to 1.25 eV (300-1000 nm), were between 1.5-3 and 0.05-0.2, respectively. The optical band gaps were deduced from the absorption coefficient according to solid band theory. The electrochromic measurements revealed that 2% Er doped CeO2 films grown on ITO + WO3 substrates had highest charge density compared to the other samples. Long-time cyclic voltammetry (CV) and chronoamperometry (CA) measurements were carried out to investigate the stability of this film.

  • 38.
    Unosson, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Welch, Ken
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Persson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Engqvist, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Stability and prospect of UV/H2O2 activated titania films for biomedical use2013In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 285, no Part B, p. 317-323Article in journal (Refereed)
    Abstract [en]

    Biomedical implants and devices that penetrate soft tissue are highly susceptible to infection, but also accessible for UV induced decontamination through photocatalysis if coated with suitable surfaces. As an on-demand antibacterial strategy, photocatalytic surfaces should be able to maintain their antibacterial properties over repeated activation. This study evaluates the surface properties and photocatalytic performance of titania films obtained by H2O2-oxidation and heat treatment of Ti and Ti-6Al-4V substrates, as well as the prospect of assisting photocatalytic reactions with H2O2 for improved efficiency. H2O2-oxidation generated a nanoporous coating, and subsequent heat treatment above 500 °C resulted in anatase formation. Tests using photo-assisted degradation of rhodamine B showed that prior to heat treatment, an initially high photocatalytic activity (PCA) of H2O2-oxidized substrates decayed significantly with repeated testing. Heat treating the samples at 600 °C resulted in stable yet lower PCA. Addition of 3% H2O2 during the photo-assisted reaction led to a substantial increase in PCA due to synergetic effects at the surface and H2O2 photolysis, the effect being most notable for non-heat treated samples. Both heat treated and non-heat treated samples showed stable PCA through repeated tests with H2O2-assisted photocatalysis, indicating that the combination of H2O2-oxidized titania films, UV light and added H2O2 can improve efficiency of these photocatalytic surfaces.

  • 39.
    Vargas, Angelo
    et al.
    ETH, Inst Chem & Bioengn, Dept Chem & Appl Biosci, HCI, CH-8093 Zurich, Switzerland..
    Shnitko, Ivan
    ETH, Inst Chem & Bioengn, Dept Chem & Appl Biosci, HCI, CH-8093 Zurich, Switzerland..
    Teleki, Alexandra
    ETH, Inst Proc Engn, Dept Mech & Proc Engn, CH-8092 Zurich, Switzerland..
    Weyeneth, Stephen
    Univ Zurich, Inst Phys, CH-8057 Zurich, Switzerland..
    Pratsinis, Sotiris E.
    ETH, Inst Proc Engn, Dept Mech & Proc Engn, CH-8092 Zurich, Switzerland..
    Baiker, Alfons
    ETH, Inst Chem & Bioengn, Dept Chem & Appl Biosci, HCI, CH-8093 Zurich, Switzerland..
    Structural dependence of the efficiency of functionalization of silica-coated FeOx magnetic nanoparticles studied by ATR-IR2011In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 257, no 7, p. 2861-2869Article in journal (Refereed)
    Abstract [en]

    The efficiency of propylamino functionalization of magnetic silica-coated FeOx nanoparticles prepared by different methods, including coprecipitation and flame aerosol synthesis, has been evaluated by attenuated total reflection infrared spectroscopy (ATR-IR) combined with a specific surface reaction, thus revealing the availability of the grafted functional groups. Large differences in the population of reactive groups were observed for the investigated materials, underlining the tight relation between the structure of nanoparticles and their suitability for organic functionalization. The materials possessed different core structure, surface area, and porosity, as evidenced by transmission electron microscopy and nitrogen adsorption-desorption isotherms. Grafting of aminopropyl groups using a standard procedure based on reaction with (3-aminopropyl) trimethoxysilane as source of the propylamino groups was performed, followed by classical dry analysis methods to determine the specific concentration of the organic functional groups (in mmol g(-1) of material). ATR-IR spectroscopy in a specially constructed reactor cell was applied as wet methodology to determine the chemically available amount of such functional groups, showing that the materials possess largely different loading capacity, with a variability of up to 70% in the chemical availability of the organic functional group. The amount of (3-aminopropyl) trimethoxysilane used for functionalization was optimized, thus reaching a saturation limit characteristic of the material. (C) 2010 Elsevier B. V. All rights reserved.

  • 40.
    Walle, Lars Erik
    et al.
    Norwegian University of Science and Technology (NTNU).
    Ragazzon, Davide
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Borg, Anne
    Norwegian University of Science and Technology (NTNU).
    Uvdal, Per
    Sandell, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Photoemission studies of water dissociation on rutile TiO2(110): Aspects on experimental procedures and the influence of steps2014In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 303, p. 245-249Article in journal (Refereed)
    Abstract [en]

    The composition of the first water layer on the stoichiometric rutile TiO2 (1 1 0) surface was studied with the use of synchrotron radiation photoelectron spectroscopy. The same H2O–OH balance was reached using different preparation procedures and there was no difference between H2O and D2O. On this basis, we rule out the possibility that the partially dissociated layer is an artifact caused by photon irradiation during measurements. Pre-deposition of Au at room temperature, primarily decorating step edges [e.g. S.A. Tenney et al. J. Phys. Chem. C 115 (2011) 11112] decreases the water uptake but does not change the relative amount that dissociates. This implies that the observed H2O–OH balance is not controlled by dissociation at steps and subsequent out-diffusion of hydrogens on the terraces. That is, the formation of a partially dissociated water layer is an inherent property of stoichiometric terraces.

  • 41. Wang, Baochang
    et al.
    Lilja, Mirjam
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Ma, Taoran
    Soerensen, Jan
    Steckel, Hartwig
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Theoretical and experimental study of the incorporation of tobramycin and strontium-ions into hydroxyapatite by means of co-precipitation2014In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 314, p. 376-383Article in journal (Refereed)
    Abstract [en]

    Antibiotic incorporation into hydroxyapatite (HA) coatings by co-precipitation and the impact of bone relevant doping elements on the adsorption kinetics are investigated from both theoretical and experimental points of view. Tobramycin interactions with bioactive TiO2 and HA surfaces are analyzed using density functional theory. According to the calculations, the drug molecule has larger adsorption energy than the Ca+ ion on both surfaces under study in Phosphate Buffered Saline (PBS). The results support the experimental observations that HA nucleation and growth are strongly limited on TiO2 surfaces in the presence of clinically relevant antibiotic concentrations in PBS. The drug molecule is more likely to adopt parallel arrangement onto the HA surface, as the adsorption energy of such arrangement is higher compared to a perpendicular one. Strontium substitution of the HA surface is found to results in a weaker drug-surface interaction, and leads also to a decrease in coating thickness. However, the presence of strontium gives rise to a coating morphology with enhanced drug incorporation capacity and slower antibiotic release compared to non-substituted, co-precipitated counterparts. Our theoretical calculation results were found to be in excellent agreement with experimental data and provide a powerful tool to understand the interaction mechanism between drug and different surface chemistries necessary for development of future versatile orthopedic and dental implant surfaces.  

  • 42. Zheng, Liqing
    et al.
    Gao, Fangyuan
    Zhao, Shuxi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Zhou, Fuyun
    Nshimiyimana, Jean Pierre
    Diao, Xungang
    Optical design and co-sputtering preparation of high performance Mo-SiO2 cermet solar selective absorbing coating2013In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 280, p. 240-246Article in journal (Refereed)
    Abstract [en]

    In order to optimize and prepare high performance Mo-SiO2 cermet solar selective absorbing coating, a series of Mo-SiO2 cermet films with different metal volume fraction were deposited on optical glass using mid-frequency (MF) and radio frequency (RF) co-sputtering. The reflectance (R) and transmittance (T) in the wavelength range of 250-2500 nm have been simulated using SCOUT software with different dielectric function models. The optical constants, film thickness, metal volume fraction and other parameters have been deduced from the modeling. The fitted optical constants were then used to simulate and optimize the Mo-SiO2 solar selective coating and samples were prepared based on the optimized parameters. The Maxwell Garnett (MG) and Bruggeman (BR) effective-medium theory have been added in the dielectric function models to describe low metal volume fraction cermet layer (LMVF) and high metal volume fraction cermet layer (HMVF), separately. The optical spectra (R and T) of all single films were in a good agreement with the fitted spectra by dielectric function models. The experimental measured reflectance of the solar selective coating was also in rather good agreement with the optimized result. The solar absorptance of theoretically optimized selective coating was 0.945, while the absorptance of the experimental coating was 0.95. The thermal emittance of 0.15 (at 400 degrees C) was obtained. 

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