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  • 401.
    Rehnlund, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Pettersson, Jean
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical 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.
    Lithium trapping in microbatteries based on lithium- and Cu2O-coated copper nanorods2018In: ChemistrySelect, E-ISSN 2365-6549, Vol. 3, no 8, p. 2311-2314Article in journal (Refereed)
    Abstract [en]

    Microbatteries based on three-dimensional (3D) electrodes composed of thin films of Li and Cu2O coated on Cu nanorod current collectors by electrodeposition and spontaneous oxidation, respectively, are described and characterised electrochemically. High-resolution scanning electron microscopy (HR-SEM) data indicate that the Li electrodeposition resulted in a homogenous coverage of the Cu nanorods and elemental analyses were also used to determine the amount of lithium in the Li-coated electrodes. The results show that 3D Cu2O/Cu electrodes can be cycled versus 3D Li/Cu electrodes but that the capacity decreased during the cycling due to Li trapping in the Cu current collector of the 3D Li/Cu electrode. These findings highlight the problem of using copper current collectors together with metallic lithium as the formation of a solid solution yields considerable losses of electroactive lithium and hence capacity.

  • 402.
    Rehnlund, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Pettersson, Jean
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical 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.
    Microbatteries based on 3D Li and Cu2O coated Cu nanorodsManuscript (preprint) (Other academic)
  • 403.
    Rehnlund, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Valvo, Mario
    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.
    Electrodeposition of Vanadium Oxide/Manganese Oxide Hybrid Thin Films on Nanostructured Aluminum Substrates2014In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 161, no 10, p. D515-D521Article in journal (Refereed)
    Abstract [en]

    Electrodeposition of functional coatings on aluminum electrodes in aqueous solutions often is impeded by the corrosion of aluminum. In the present work it is demonstrated that electrodeposition of vanadium, oxide films on nanostructured aluminum substrates can be achieved in acidic electrolytes employing a novel strategy in which a thin interspacing layer of manganese oxide is first electrodeposited on aluminum microrod substrates. Such deposited films, which were studied using SEM, XPS, XRD, and surface enhances Raman scattering as well as chronopotentiometry, are shown to comprise a mixture of vanadium oxidation states (i.e. IV and V). As this all-electrochemical approach circumvents the problems associated with aluminum corrosion, the approach provides new possibilities for the electrochemical coating of nanostructured Al substrates with functional layers of metal oxides. The latter significantly facilitates the development of new procedures for the manufacturing of three-dimensional aluminum based electrodes for lithium ion microbatteries. (C) The Author(s) 2014. Published by ECS. All rights reserved.

  • 404.
    Rehnlund, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Stockholm University.
    Ångstrom, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Stockholm University.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic 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.
    Electrochemical fabrication and characterization of Cu/Cu2O multi-layered micro and nanorods in Li-ion batteries2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 32, p. 13591-13604Article in journal (Refereed)
    Abstract [en]

    Electrodes composed of freestanding nano- and microrods composed of stacked layers of copper and cuprous oxide have been fabricated using a straightforward one-step template-assisted pulsed galvanostatic electrodeposition approach. The approach provided precise control of the thickness of each individual layer of the high-aspect-ratio rods as was verified by SEM, EDS, XRD, TEM and EELS measurements. Rods with diameters of 80, 200 and 1000 nm were deposited and the influence of the template pore size on the structure and electrochemical performance of the conversion reaction based electrodes in lithium-ion batteries was investigated. The multi-layered Cu2O/Cu nano-and microrod electrodes exhibited a potential window of more than 2 V, which was ascribed to the presence of a distribution of Cu2O (and Cu, respectively) nanoparticles with different sizes and redox potentials. As approximately the same areal capacity was obtained independent of the diameter of the multi-layered rods the results demonstrate the presence of an electroactive Cu2O layer with a thickness defined by the time domain of the measurements. It is also demonstrated that while the areal capacity of the electrodes decreased dramatically when the scan rate was increased from 0.1 to 2 mV s(-1), the capacity remained practically constant when the scan rate was further increased to 100 mV s(-1). This behaviour can be explained by assuming that the capacity is limited by the lithium ion diffusion rate though the Cu2O layer generated during the oxidation step. The electrochemical performance of present type of 3-D multi-layered rods provides new insights into the lithiation and delithiation reactions taking place for conversion reaction materials such as Cu2O.

  • 405.
    Rehnlund, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Stockholm University.
    Ångström, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic 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.
    Electrochemical fabrication of 3D Cu/Cu2O multilayered nanostructures2015Conference paper (Other academic)
    Abstract [en]

    The possibility of engineering multilayered nanostructures and coatings with a wide variety of compositions has in the last decades attracted a great deal of scientific interest. In fact, multilayered structures with tailored properties have been investigated for solar conversion [1], the semiconductor industry [2] and tribological systems [3].Electrochemical engineering has emerged as a particularly promising technique for fabrication of nanostructured electrodes with excellent control on morphology [4]. The technique shows great promise in the copper system as Cu/Cu2O multilayers have been produced by allowing spontaneous potential oscillations to dictate the deposition [5, 6].Although this natural phenomenon provides a simple route to obtain mixedcomposition, improved control is required to obtain fine detailed multilayers. The presented study has been focused on preventing spontaneous potential oscillations to provide controlled deposition of Cu/Cu2O multilayers. In addition copper based multilayers have hereby been transported into the world of 3D electrodes via a one-step electrodeposition fabrication.

    Figure 1: Multilayered Cu/Cu2O nanopillars fabricated through electrodeposition.

    References

    1. W. Wei, et al.. Advanced Materials, 2010. 22: p. 4770-4774.

    2. G. Binasch, et al.. Physical Review B, 1989. 39: p. 4828-4830.

    3. P. E. Hovsepian, et al.. Surface and Coatings Technology, 1999. 116-119: p.727-734.

    4. K. Edström, et al.. The Electrochemical Society Interface, 2011. 20: p. 41-46.

    5. J. Eskhult, et al.. Journal of Electroanalytical Chemistry, 2006. 594: p. 35-49.6. S. Leopold, et al.. Electrochimica Acta, 2002. 47

  • 406.
    Rickard, Eriksson
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Adam, Sobkowiak
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Jonas, Ångström
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Martin, Sahlberg
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Torbjörn, Gustafsson
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Kristina, Edström
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Fredrik, Björefors
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Formation of Tavorite-Type LiFeSO4F Followed by In Situ X-ray DiffractionManuscript (preprint) (Other academic)
  • 407. Rosental, Arnold
    et al.
    Tarre, Aivar
    Gerst, Alar
    Kasikov, Aarne
    Lu, Jun
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ottosson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Uustare, Teet
    Epitaxial Single and Double Nanolayers of SnO2 and TiO2 for Resistive Gas Sensors2013In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 13, no 5, p. 1648-1655Article in journal (Refereed)
    Abstract [en]

    Rutile TiO2 (1 0 1) and cassiterite SnO2 (1 0 1) epitaxial single and double nanolayers, the latter stacked in either sequence, are atomic layer deposited on r-cut alpha-Al2O3(0 1 (1) over bar 2) substrates. Thickness of the layers is varied. Epitaxial quality of the films is characterized by X-ray diffraction (XRD), reflection high-energy electron diffraction, and transmission electron microscopy. In gas response measurements, as-grown films and the films coated with electron-beam evaporated Pt nanoclusters are exposed, at 350 degrees C, to H-2, CO, and CH4 diluted in air. In response to test gas concentrations of 30 parts per million (ppm), the films with a thickness of order of 10 nm exhibit, depending on the makeup and gas, as high as two- to five-fold decrease in the resistance. It is shown that the platinum surface catalyst is effective in accelerating the response and recovery processes. The transition times of the order of a few tens of seconds are observed. The results demonstrate the feasibility of gas sensing with single-crystal-like nanolayer films. Comparison of sensor characteristics of such quasi-2D nanostructures and the literature data relevant to individual nanowires, nanorods, and nanobelts, i.e., typical representatives of the quasi-1D structures, shows that, as to H-2, CO, and CH4, both structures are worthy competitors.

  • 408.
    Ruan, Changqing
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Wang, Zhaohui
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lindh, Jonas
    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.
    Carbonized cellulose beads for efficient capacitive energy storage2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 6, p. 3545-3556Article in journal (Refereed)
    Abstract [en]

    Natural biomaterials, including polysaccharides and amino acids, provide a sustainable source of functional carbon materials for electric energy storage applications. We present a one-pot reductive amination process to functionalize 2,3-dialdehyde cellulose (DAC) beads with chitosan and l-cysteine to provide single (N)- and dual (N/S)-doped materials. The functionalization enables the physicochemical properties of the materials to be tailored and can provide carbon precursors with heteroatom doping suitable for energy storage applications. Scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis were used to characterize the changes to the beads after functionalization and carbonization. The results of X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy verified that the doping was effective, while the nitrogen sorption isotherms and pore-size distributions of the carbonized beads showed the effects of doping with different hierarchical porosities. In the electrochemical experiments, three kinds of carbon beads [pyrolyzed from DAC, chitosan-crosslinked DAC (CS-DAC) and l-cysteine-functionalized DAC] were used as electrode materials. Electrodes of carbonized CS-DAC beads had a specific capacitance of up to 242 F g(-1) at a current density of 1 A g(-1). These electrodes maintained a capacitance retention of 91.5% after 1000 charge/discharge cycles, suggesting excellent cycling stability. The results indicate that reductive amination of DAC is an effective route for heteroatom doping of carbon materials to be used as electrode active materials for energy storage.

  • 409.
    Rubino, Stefano
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Razaq, Aamir
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Leifer, Klaus
    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.
    Spatial Mapping of Elemental Distributions in Polypyrrole-Cellulose Nanofibers using Energy-Filtered Transmission Electron Microscopy2010In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 114, no 43, p. 13644-13649Article in journal (Refereed)
    Abstract [en]

    The energy-filtered transmission electron microscopy (EFTEM) technique has been used to study ion-exchange processes in conductive polymer composite nanofibers. The elemental distributions of carbon, nitrogen, oxygen, chlorine, boron, phosphorus, molybdenum, and sulfur within polypyrrole-cellulose nanofibers, used as potential controlled electrochemical solid phase extraction media, have been studied by EFTEM. The distribution of ions within the polypyrrole-cellulose nanofibers and the penetration depth of ions into the material as a function of the size and charge of the latter were investigated. Further, the spatial distribution of single stranded DNA hexamers inside polypyrrole-cellulose nanofibers was mapped subsequent to the electrochemically controlled extraction of DNA from a borate buffer solution. The results show that the EFTEM mapping technique provides unpreceded possibilities for studies of the distribution of ions inside conductive polymer composites.

  • 410.
    Rubino, Stefano
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Razaq, Aamir
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Leifer, Klaus
    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.
    Tracking Ion Distributions in Polypyrrole Coated Cellulose Nanofibers by means of Energy Filtered Transmission Electron Microscopy2010In: 17th International Microscopy Congress - Rio de Janeiro19-24 September 2010, 2010Conference paper (Refereed)
  • 411.
    Rubino, Stefano
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Razaq, Aamir
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Tracking Ion Distributions in Polypyrrole Coated Cellulose Nanofibers by means of Energy Filtered Transmission Electron Microscopy2010Conference paper (Refereed)
  • 412.
    Sahlberg, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Brant, William R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Berger, Rolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Real-time in situ monitoring of the topotactic transformation of TlCu5Se3 into metastable o-TlCu4Se32016In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 685, p. 436-441Article in journal (Refereed)
    Abstract [en]

    The transformation within the solid state of tetragonal TlCu5Se3 into the metastable orthorhombic form of TlCu4Se3 by oxidative copper leaching in concentrated ammonia solution has been studied in situ by conventional X-ray powder diffraction. The ease with which the reaction occurs illustrates a comparatively high diffusion coefficient typical of copper sulphides and selenides. The diffraction patterns of the parent phase as well as the product remain sharp during the process, indicating strong topotaxy in the first-order transformation that is effectuated by the access of oxygen while the accompanying released copper enters the liquid phase. The transformation was followed in a real-time mode, leading to a complete transformation of the amount probed.

  • 413.
    Sahlberg, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Karlsson, Dennis
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Zlotea, Claudia
    Univ Paris Est, Inst Chim & Mat Paris Est, UMR7182, CNRS,UPEC, 2-8 Rue Henri Dunant, F-94320 Thiais, France..
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Superior hydrogen storage in high entropy alloys2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 36770Article in journal (Refereed)
    Abstract [en]

    Metal hydrides (MHx) provide a promising solution for the requirement to store large amounts of hydrogen in a future hydrogen-based energy system. This requires the design of alloys which allow for a very high H/M ratio. Transition metal hydrides typically have a maximum H/M ratio of 2 and higher ratios can only be obtained in alloys based on rare-earth elements. In this study we demonstrate, for the first time to the best of our knowledge, that a high entropy alloy of TiVZrNbHf can absorb much higher amounts of hydrogen than its constituents and reach an H/M ratio of 2.5. We propose that the large hydrogen-storage capacity is due to the lattice strain in the alloy that makes it favourable to absorb hydrogen in both tetrahedral and octahedral interstitial sites. This observation suggests that high entropy alloys have future potential for use as hydrogen storage materials.

  • 414.
    Sahlberg, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Ångström, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Zlotea, Claudia
    Beran, Premsyl
    Latroche, Michel
    Pay Gómez, Ceasar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Structure and hydrogen storage properties of the hexagonal Laves phase Sc(Al1-xNix)22012In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 196, p. 132-137Article in journal (Refereed)
    Abstract [en]

    The crystal structures of hydrogenated and unhydrogenated Sc(Al 1-xNi x) 2 Laves phases have been studied by combining several diffraction techniques and it is shown that hydrogen is situated interstitially in the A 2B 2-sites, which have the maximum number of scandium neighbours. The hydrogen absorption/desorption behaviour has also been investigated. It is shown that a solid solution of hydrogen forms in the mother compound. The hydrogen storage capacity exceeds 1.7 H/f.u. at 374 K, and the activation energy of hydrogen desorption was determined to 4.6 kJ/mol H 2. It is shown that these compounds share the same local coordination as Frank-Kasper-type approximants and quasicrystals, which opens up the possibility of finding many new hydride phases with these types of crystal structures.

  • 415. Samuelsson, Mattias
    et al.
    Sarakinos, Kostas
    Högberg, Hans
    Lewin, Erik
    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.
    Wälivaara, Bengt
    Ljungcrantz, Henrik
    Helmersson, Ulf
    Growth of Ti-C nanocomposite films by reactive high power impulse magnetron sputtering under industrial conditions2012In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 206, no 8-9, p. 2396-2402Article in journal (Refereed)
    Abstract [en]

    Titanium carbide (TiC) films were deposited employing high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS) in an Ar-C2H2 atmosphere of various compositions. Analysis of the structural, bonding and compositional characteristics revealed that the deposited films are either TiC and hydrogenated amorphous carbon (a-C:H) nanocomposites, nanocrystalline TiC, or Ti/Tic, depending on the C/Ti ratio. It was found that Ti-C films grown by HiPIMS show a C/Ti ratio of close to 1 for a wide C2H2 flow range (4-15 sccm), with free C ranging from 0 to 20%. Thus, films ranging from near stoichiometric single phase TiC to TiC/a-C:H nanocomposites can be synthesized. This was not the case for DCMS, where films grown using similar deposition rates as for HiPIMS formed larger fractions of amorphous C matrix, thus being nanocomposites in the same C2H2 (above 4 sccm) flow range. For a C/Ti ratio of 1 the resistivity is low (4-8 x 10(2) mu Omega cm) for the HiPIMS films, and high (>100x 10(2) mu Omega cm) for the DCMS films. The hardness also shows a big difference with 20-27 and 6-10 GPa for HiPIMS and DCMS grown films, respectively.

  • 416.
    Sandström, Patricia
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Biocompatibility tests performed on nanoporous aluminum oxide coated with polyethyleneglycol and titanium dioxide2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Anodized aluminium oxide may be chemically treated to yield a uniform self-organized distribution of pores with a specific pore diameter. The thickness of in-house anodized alumina and its pore size can be modified by changing the electrolyte, the temperature of the electrolyte, the time of anodization and the potential over the anodized plates. 

    In this thesis, a method for anodized aluminium oxide (AAO) was optimized for creating custom-made porous alumina membranes and coating them with TiO2 and polyethylene glycol (PEG). The purpose of finding a method to create porous alumina oxide with specific pore diameters was to eventually use these membranes for use in contact with human living tissue, allowing wanted nutrients and fluid to pass in and out.

         SEM images showed that a reproducible method has been established for the membrane production, where the pore diameter is ~ 300nm and the thickness of the oxide is approximately 100µm. The SEM images also showed that the pores are stable and uniform over the entire aluminum plate where they are initially produced.

         As a test for biocompatibility, the membranes were implanted into the hipbone of pigs.

    The histology test showed fibrosis around the location where the membranes were placed. An observation during the extraction was swollenness in the surrounding tissue, which indicates inflammation around the implant. In this respect, the membranes cannot be used for the purpose intended.

  • 417. Sarius, N. G.
    et al.
    Lauridsen, J.
    Lewin, Erik
    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.
    Hogberg, H.
    Oberg, A.
    Sarova, G.
    Staperfeld, G.
    Leisner, P.
    Eklund, P.
    Hultman, L.
    Contact Resistance of Ti-Si-C-Ag and Ti-Si-C-Ag-Pd Nanocomposite Coatings2012In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 41, no 3, p. 560-567Article in journal (Refereed)
    Abstract [en]

    Ti-Si-C-Ag-Pd and Ti-Si-C-Ag nanocomposite coatings were deposited by direct-current magnetron sputtering on Cu substrates with an electroplated Ni layer. Analytical electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy show that the nanocomposites consist of TiC, Ag:Pd, and amorphous SiC. The contact resistance of these coatings against a spherical Au-Co surface was measured for applied contact forces up to 5 N. Ti-Si-C-Ag-Pd coatings with Ag:Pd top coating had similar to 10 times lower contact resistance at contact forces below 1 N (similar to 10 m Omega at similar to 0.1 N), and 2 to 3 times lower for contact forces around 5 N (< 1 m Omega at 5 N), compared with the Ti-Si-C-Ag coating.

  • 418. Sarius, N. G.
    et al.
    Lauridsen, J.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lu, J.
    Hogberg, H.
    Oberg, A.
    Ljungcrantz, H.
    Leisner, P.
    Eklund, P.
    Hultman, L.
    Ni and Ti diffusion barrier layers between Ti-Si-C and Ti-Si-C-Ag nanocomposite coatings and Cu-based substrates2012In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 206, no 8-9, p. 2558-2565Article in journal (Refereed)
    Abstract [en]

    Sputtered Ni and Ti layers were investigated as a diffusion barrier to substitute electroplated Ni between Ti-Si-C and Ti-Si-C-Ag nanocomposite coatings and Cu or CuSn substrates. Samples were subjected to thermal annealing studies by exposure to 400 degrees C for 11 h. Dense diffusion barrier and coating hindered Cu from diffusing to the surface. This condition was achieved for electroplated Ni in combination with magnetron-sputtered Ti-Si-C and Ti-Si-C-Ag layers deposited at 230 degrees C and 300 degrees C. and sputtered Ti or Ni layers in combination with Ti-Si-C-Ag deposited at 300 degrees C.

  • 419.
    Sawadjoon, Supaporn
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sjöberg, Per J. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Eriksson, Lars
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Equilibrium Study of Pd(dba)2 and P(OPh)3 in the Pd-Catalyzed Allylation of Aniline by Allyl Alcohol2014In: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 33, no 1, p. 249-253Article in journal (Refereed)
    Abstract [en]

    Reaction of Pd(dba)2 and P(OPh)3 shows a unique equilibrium where the Pd[P(OPh)3]3 complex is favored over both Pd(dba)[P(OPh)3]2 and Pd[P(OPh)3]4 complexes at room temperature. At a lower temperature, Pd[P(OPh)3]4 becomes the most abundant complex in solution. X-ray studies of Pd[P(OPh)3]3 and Pd(dba)[P(OPh)3]2 complexes show that both complexes have a trigonal geometry with a Pd–P distance of 2.25 Å due to the π-acidity of the phosphite ligand. In solution, pure Pd(dba)[P(OPh)3]2 complex equilibrates to the favored Pd[P(OPh)3]3 complex, which is the most stable complex of those studied, and also forms the most active catalytic species. This catalyst precursor dissociates one ligand to give the reactive Pd[P(OPh)3]2, which performs an oxidative addition of nonmanipulated allyl alcohol to generate the π-allyl-Pd[P(OPh)3]2 intermediate according to ESI-MS studies.

  • 420.
    Schwarzwaelder, Susanne
    et al.
    Tech Univ Munich, Walter Schottky Inst, Garching, Germany.
    Csiki, Reka
    Tech Univ Munich, Walter Schottky Inst, Garching, Germany.
    Zhao, Shuainan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Larsson, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Schwartz, Jeffrey
    Princeton Univ, Chem, Princeton, NJ 08544 USA.
    Stutzmann, Martin
    Tech Univ Munich, Walter Schottky Inst, Garching, Germany.
    Wurstbauer, Ursula
    Tech Univ Munich, Walter Schottky Inst, Garching, Germany.
    Cattani-Scholz, Anna
    Tech Univ Munich, Walter Schottky Inst, Garching, Germany.
    Tuning the physical properties of MoS2 membranes through organophosphonate-based surface functionalization2017In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 253Article in journal (Other academic)
  • 421. Serebrennikova, I
    et al.
    Paramasivam, I
    Roy, P
    Wei, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Virtanen, S
    Schmuki, P
    Steel corrosion in alkaline batteries2009In: Electrochimica Acta, Vol. 54, no 22, p. 5216-5222Article in journal (Refereed)
  • 422.
    Shafeie, Samrand
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Fang, Hailiang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hedlund, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Nyberg, Axel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Gunnarsson, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    One step towards MnAl-based permanent magnets: Differences in magnetic, and microstructural properties from an intermediate annealing step during synthesis2019In: Journal of Solid State Chemistry, ISSN 0022-4596, E-ISSN 1095-726X, Vol. 274, p. 229-236Article in journal (Refereed)
    Abstract [en]

    The influence of an additional annealing step during synthesis on the preparation of MnAl based permanent magnet alloys has been investigated. Bulk samples of Mn55Al45C2 alloys were synthesized using induction heating through drop synthesis from 1400 °C. Samples produced using cooling directly from 1400 °C (from the melt), and from 1400 °C to an intermediate annealing step at 1200 °C for ~ 30 min before cooling were compared with respect to differences in phase purity, microstructure and magnetic properties. We found that the phase purity was significantly enhanced using the route with an intermediate annealing step at 1200 °C. From XRD the phase purity of the tau-phase was improved from ~ 91 wt% for the sample cooled directly from 1400 °C to ~ 95.1 - 99.5 wt% for the sample exposed to an intermediate annealing step before cooling. Additionally, EBSD, and SEM with EDS indicates a clear difference in the phase composition and differences in the distribution of the magnetic tau phase and the non-magnetic epsilon-, beta-, and gamma-phases. Magnetic properties also indicate, an improvement in saturation magnetization for the sample exposed to the extra annealing step during synthesis. Our results suggest that an intermediate annealing step in the production of MnAl based alloys will provide a simple way of achieving better phase purity and magnetic properties in the bulk alloy.

  • 423.
    Sheikh, Saad
    et al.
    Chalmers Univ Technol, Ind & Mat Sci, S-41296 Gothenburg, Sweden.
    Bijaksana, Muhammad Kurnia
    Chalmers Univ Technol, Ind & Mat Sci, S-41296 Gothenburg, Sweden.
    Motallebzadeh, Amir
    Koc Univ, Surface Sci & Technol Ctr KUYTAM, TR-34450 Istanbul, Turkey.
    Shafeie, Samrand
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lozinko, Adrianna
    Chalmers Univ Technol, Ind & Mat Sci, S-41296 Gothenburg, Sweden.
    Gan, Lu
    Natl Inst Mat Sci, Sengen 1-2-1, Tsukuba, Ibaraki 3050047, Japan;Waseda Univ, Dept Nanosci & Nanoengn, Shinjuku Ku, 3-4-1 Okubo, Tokyo 1698555, Japan.
    Tsao, Te-Kang
    Natl Inst Mat Sci, Sengen 1-2-1, Tsukuba, Ibaraki 3050047, Japan.
    Klement, Uta
    Chalmers Univ Technol, Ind & Mat Sci, S-41296 Gothenburg, Sweden.
    Canadinc, Demircan
    Koc Univ, AMG, TR-34450 Istanbul, Turkey.
    Murakami, Hideyuki
    Natl Inst Mat Sci, Sengen 1-2-1, Tsukuba, Ibaraki 3050047, Japan;Waseda Univ, Dept Nanosci & Nanoengn, Shinjuku Ku, 3-4-1 Okubo, Tokyo 1698555, Japan.
    Guo, Sheng
    Chalmers Univ Technol, Ind & Mat Sci, S-41296 Gothenburg, Sweden.
    Accelerated oxidation in ductile refractory high-entropy alloys2018In: Intermetallics (Barking), ISSN 0966-9795, E-ISSN 1879-0216, Vol. 97, p. 58-66Article in journal (Refereed)
    Abstract [en]

    Refractory high-entropy alloys (RHEAs) are promising candidates for new-generation high temperature materials, but they generally suffer from room temperature brittleness and unsatisfactory high-temperature oxidation resistance. There currently lack efforts to address to these two critical issues for RHEAs at the same time. In this work, the high temperature oxidation resistance of a previously identified ductile Hf0.5Nb0.5Ta0.5Ti1.5Zr RHEA is studied. An accelerated oxidation or more specifically, pesting, in the temperature range of 600-1000 degrees C is observed for the target RHEA, where the oxidation leads the material to catastrophically disintegrate into powders. The pesting mechanism is studied here, and is attributed to the failure in forming protective oxide scales accompanied by the accelerated internal oxidation. The simultaneous removal of zirconium and hafnium can eliminate the pesting phenomenon in the alloy. It is believed that pesting can also occur to other equiatomic and non-equiatomic quinary Hf-Nb-Ta-Ti-Zr or quaternary Hf-Nb-Ti-Zr and Hf-Ta-Ti-Zr RHEAs, where all currently available ductile RHEAs are identified. Therefore, the results from this work will provide crucial perspectives to the further development of RHEAs as novel high-temperature materials, with balanced room-temperature ductility and high-temperature oxidation resistance.

  • 424.
    Sheikh, Saad
    et al.
    Chalmers Univ Technol, Ind & Mat Sci, S-41296 Gothenburg, Sweden.
    Gan, Lu
    Natl Inst Mat Sci, Sengen 1-2-1, Tsukuba, Ibaraki 3050047, Japan;Waseda Univ, Dept Nanosci & Nanoengn, Shinjuku Ku, 3-4-1 Okubo, Tokyo 1698555, Japan.
    Tsao, Te-Kang
    Waseda Univ, Dept Nanosci & Nanoengn, Shinjuku Ku, 3-4-1 Okubo, Tokyo 1698555, Japan.
    Murakami, Hideyuki
    Natl Inst Mat Sci, Sengen 1-2-1, Tsukuba, Ibaraki 3050047, Japan;Waseda Univ, Dept Nanosci & Nanoengn, Shinjuku Ku, 3-4-1 Okubo, Tokyo 1698555, Japan.
    Shafeie, Samrand
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Guo, Sheng
    Chalmers Univ Technol, Ind & Mat Sci, S-41296 Gothenburg, Sweden.
    Aluminizing for enhanced oxidation resistance of ductile refractory high-entropy alloys2018In: Intermetallics (Barking), ISSN 0966-9795, E-ISSN 1879-0216, Vol. 103, p. 40-51Article in journal (Refereed)
    Abstract [en]

    Refractory high-entropy alloys (RHEAs) emerge as promising candidate materials for ultrahigh-temperature applications. One critical issue to solve for RHEAs is their balanced oxidation resistance and mechanical properties, mainly room-temperature ductility for the latter. Recently, it was found that existing ductile RHEAs are subject to catastrophic accelerated oxidation, also known as pesting. In this work, both alloying and surface coating, are applied to enhance the oxidation resistance of ductile RHEAs, with the focus on surface coating using the pack cementation method and more specifically, aluminizing. The oxidation resistance of two RHEAs, Hf0.5Nb0.5Ta0.5Ti1.5Zr, one recently identified ductile RHEA which pests in the temperature range of 600-1000 degrees C, and Al0.5Cr0.25Nb0.5Ta0.5Ti1.5, the newly designed ductile RHEA which does not pest but embrittles after oxidation, are studied after aluminizing at 900 degrees C using three different pack components. Aluminizing, if using the appropriate pack cementation parameters, can avoid pesting in Hf0.5Nb0.5Ta0.5Ti1.5Zr and alleviate the oxidation induced embrittlement in Al0.5Cr0.25Nb0.5Ta0.5Ti1.5, and holds the promise for further improving the RHEAs as potential ultrahigh-temperature materials.

  • 425.
    Shinde, Deodatta
    et al.
    Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden.
    Fritze, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Thuvander, Mattias
    Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden.
    Malinovskis, Paulius
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Riekehr, Lars
    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.
    Stiller, Krystyna
    Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden.
    Elemental Distribution in CrNbTaTiW-C High Entropy Alloy Thin Films2019In: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115, Vol. 25, no 2, p. 489-500Article in journal (Refereed)
    Abstract [en]

    The microstructure and distribution of the elements have been studied in thin films of a near-equimolar CrNbTaTiW high entropy alloy (HEA) and films with 8 at.% carbon added to the alloy. The films were deposited by magnetron sputtering at 300 degrees C. X-ray diffraction shows that the near-equimolar metallic film crystallizes in a single-phase body centered cubic (bcc) structure with a strong (110) texture. However, more detailed analyses with transmission electron microscopy (TEM) and atom probe tomography (APT) show a strong segregation of Ti to the grain boundaries forming a very thin Ti-Cr rich interfacial layer. The effect can be explained by the large negative formation enthalpy of Ti-Cr compounds and shows that CrNbTaTiW is not a true HEA at lower temperatures. The addition of 8 at.% carbon leads to the formation of an amorphous structure, which can be explained by the limited solubility of carbon in bcc alloys. TEM energy-dispersive X-ray spectroscopy indicated that all metallic elements are randomly distributed in the film. The APT investigation, however, revealed that carbide-like clusters are present in the amorphous film.

  • 426.
    Shuainan, Zhao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Karin, Larsson
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    A Theoretical Study of the Energetic Stability and Electronic Structure of Terminated and P-doped Diamond (100)-2x1 SurfacesManuscript (preprint) (Other academic)
  • 427.
    Shuainan, Zhao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Karin, Larsson
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    First principle study of the attachment of graphene onto non-doped and doped diamond (111)2016In: Diamond and related materials, ISSN 0925-9635, E-ISSN 1879-0062, Vol. 66, p. 52-60Article in journal (Refereed)
    Abstract [en]

    Density function theory (DFT) calculations have in the present study been used to study the adhesion of a graphene monolayer onto a non-, B-, or N-doped diamond (111) surface. Semiempirical dispersion corrections were used to take the Van-der-Waals corrections into consideration. In case of non-doped diamond as a substrate, DFT calculations (based on the local density approximation (LDA)) have shown a strong binding between graphene and the diamond (111) surface at a shorter distance (2.47 Å). The binding energy was − 14.5 kJ/mol per Cgraphene atom. In comparison, the generalized gradient spin density approximation (GG(S)A) was found to predict a weaker (− 9.6 kJ/mol) interfacial bond at a distance of 3.10 Å. For the situation with B-, or N-, doped diamond, the optimized shorter diamond-graphene distance was found to be 3.01 and 3.24 Å, respectively. The corresponding adhesion energies per Cgraphene atom was − 9.9 kJ/mol (B-doping) and − 9.6 kJ/mol (N-doping), which are quite similar to the non-doped situation (− 9.6 kJ/mol). For all situations in the present study, the graphene layer was found to remain its aromatic character. However, a minor charge transfer was observed to take place from the graphene adlayer towards the non-doped and doped diamond (111) substrates.

  • 428.
    Shuainan, Zhao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Karin, Larsson
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Theoretical Study of the Attachment of Graphene onto Different Terminated Diamond (111)Article in journal (Refereed)
    Abstract [en]

    Density functional theory (DFT) calculations have in the present study been used to study the adhesion of a graphene monolayer onto a different (H-, F-, Oontop-, OH- and Obri-) terminated, or 2x1- reconstructed, diamond (111) surface. The generalized gradient spin density approximation (GG(S)A) with the semi-empirical dispersion corrections(PBE-TS)were used in the study of the Van-der-Waals interactions. There is a weaker interfacial bond (only of type Wan-der-Waals interaction) at a distance around 3 Å (from 2.68 to 3.36 Å) for the interfacial graphene//diamond systems in the present study. The H-terminated diamond (111) surface provided the largest interaction (smallest adsorption energy: -10.6 eV) with the graphene ad-layer and in contrast, the F adsorbates provided the smallest interaction (largest adsorption energy: -2.9 eV). For all situations in the present study, the graphene layer was found to remain its aromatic character. However, there is an observed electron transfer between the graphene adlayer and the H-, Oontop- , Obri-, or OH- terminated diamond substrates. Moreover, the Oontop-terminated diamond-supported graphene shows a finite band gap.

  • 429.
    Sipola, Josefin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Quality Management during Sintering of Cemented Carbides and Cermets2015Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The magnetic properties, coercivity, Hc, and weight-specific magnetic saturation, CoM, are two important quality characteristics in cemented carbides and ceramic metals, cermets. These properties give information about grain size and binder phase content, and are influenced by the different stages in the sintering process. This master thesis aim to investigate how the magnetic properties in cemented carbides are influenced by the top temperature during sintering and how the sintering processes used for cermets can be optimized in order to gain better magnetic properties in the final products.

    During the first part of the project, the temperature range investigated was 1380°C–1520°C. The results indicate that Hc in cemented carbides has a strong temperature dependence, where increasing top temperature results in lower Hc. In order to have approval limits for the furnace control pieces that follow the process directives, the limits used today need to become narrower. Furthermore, the results show that CoM also has a temperature dependence, although not as strongly as Hc.

    During the second part of the project, already existing data of the magnetic properties in four different cermet grades were evaluated. The results indicate that the two sintering processes used in the DDK furnace are generating too high results in Hc and CoM. Optimization tests were conducted and changes implemented in order to gain better results, where the DJ1430 process now has an increased time during the solid state sintering and the DF1480 process now has an increased time during the liquid phase sintering.

  • 430.
    Sisodiya, Sheetal
    et al.
    Lund Univ, Dept Chem, Ctr Anal & Synth, SE-22100 Lund, Sweden..
    Wallenberg, L. Reine
    Lund Univ, Dept Chem, Ctr Anal & Synth, SE-22100 Lund, Sweden.;Lund Univ, Natl Ctr High Resolut Electron Microscopy, SE-22100 Lund, Sweden..
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Wendt, Ola F.
    Lund Univ, Dept Chem, Ctr Anal & Synth, SE-22100 Lund, Sweden..
    Sonogashira coupling reaction over supported gold nanoparticles: Influence of support and catalyst synthesis route2015In: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 503, p. 69-76Article in journal (Refereed)
    Abstract [en]

    This study investigates the impact of supports and synthesis routes on the performance of supported gold nanoparticles in the Sonogashira coupling reaction. The catalysts were synthesized by deposition-precipitation (DP) and incipient wetness impregnation (IMP), employing carriers of different nature (redox: CeO2, TiO2, and non-redox: Al2O3) and were characterized by various physical techniques such as X-ray fluorescence, powder X-ray diffraction, X-ray photoelectron spectroscopy, N-2 sorption, and high resolution. transmission electron microscopy. It is revealed that gold is present in the metallic state in all of the samples, independent of the nature of the support and the way of synthesis. The DP technique gave catalysts with smaller gold particles (4-14 nm), while the IMP route led to agglomeration due to presence of chlorine and resulted in distinctly larger gold particles (50-100 nm) on the supports. The evaluation of catalysts in the Sonogashira coupling of phenylacetylene and iodobenzene demonstrated that the catalysts' performance is negligibly dependent on the specific surface area of the catalysts. Synthesis paths, however, greatly affected the catalysts' activity and selectivity. All the catalysts prepared by DP gave significantly higher conversion of iodobenzene and selectivity to diphenylacetylene (desired hetero-coupled product) than their analogs prepared by IMP. This is shown to be related to the superior dispersion achieved by the DP route with the formation of smaller Au nanoparticle, which are highly active and selective. Thus, the present study explicitly establishes that the choice of proper synthesis method is vital to achieve sufficiently small nanoparticles leading to the best Sonogashira performance. Also, redox active oxide supports lead to a better performance than non-redox carriers. Despite significant leaching, the catalysis is shown to be heterogeneous. (C) 2015 Elsevier B.V. All rights reserved.

  • 431.
    Sjödin, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Karlsson, Christoffer
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Huang, Hao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Olsson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Yang, Li
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Organic Battery Materials based on Conducting Polymer Backbones with High Capacity Pending Groups2014Conference paper (Refereed)
    Abstract [en]

    Organic matter based battery materials have attracted large interest due to their inherent ability to provide an environmentally benign alternative to inorganic batteries because such materials can be produced from renewable resources via eco-efficient processes. The development of organic battery materials rely on several key factors that need to be resolved, the most important being dissolution problems, limited electronic conductivity, degradation of active material and slow redox kinetics. Conducting polymers are insoluble in most electrolytes, they are electronically conducting and show fast redox conversion but are, to some extent, unstable and have insufficient charge capacities for battery applications.

                To understand the instability of conducting polymers we have measured self discharge rates in polypyrrole at different temperatures. From these experiments it is clear that the self-discharge originates from an activated redox reaction with an activation barrier of around 0.4 eV. Although the exact nature of the redox reaction has not been identified we have been able to link the self discharge to, what is commonly referred to as, over-oxidation. Over-oxidation is common to polyacetylene, polyparaphenylene, polypyrrole and polythiophene and this mechanism of self discharge is thus a general feature of conducting polymers. This self-discharge mechanism is suppressed by low polymer doping levels, low potentials and low temperatures.     

    By attaching high capacity redox active groups onto the conducting polymer backbone the charge capacity can be increased while retaining electronic conductivity and insolubility. We have attached quinone groups to each repeat unit of polypyrrole for this purpose. Interestingly, in-situ spectroscopic measurements show that during quinone redox conversion the polymer doping level is in-fact reduced. Since the doping level of the polymer affects the rate of self-discharge the attachment of quinone units to the polypyrrole chain not only increases the charge capacity but also provides a conceptual strategy to control self discharge. 

  • 432.
    Song, Man
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Zhao, Jie
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Meng, Yu
    Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Liaoning, Peoples R China.
    Riekehr, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hou, Peng-Xiang
    Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Liaoning, Peoples R China.
    Grennberg, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Zhang, Zhi-Bin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Nitrogen-doped Reduced Graphene Oxide Hydrogel Achieved via a One-Step Hydrothermal Process2019In: CHEMNANOMAT, ISSN 2199-692X, Vol. 5, no 9, p. 1144-1151Article in journal (Refereed)
    Abstract [en]

    We report an efficient one-step method to achieve highly reduced graphene oxide (rGO) hydrogel doped with nitrogen where the rGO sheets are interconnected forming a porous structure by means of hydrothermal process. During the synthesis, ammonium formate is used as reducing reagent and simultaneously as nitrogen supplier, which delivers nitrogen-doped rGO (NRGO) hydrogel that exhibits C/O atomic ratio as high as at ~11.1 and contains decent ~5.4 at.% nitrogen. As comparison, the reduction efficiency is only half of the value and no nitrogen doping can be obtained when L-ascorbic acid is used as reducing reagent. The resultant NRGO shows enhanced electrocatalytic ability for oxygen reduced reaction indicating its great potential of the one-step method for the catalyst and energy applications. 

  • 433.
    Song, Yang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Quantum Chemical Studies of Diamond for Energy Related Applications2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Diamond is a unique material with excellent properties. As a result of the development within the area of CVD synthesis, doping and surface functionalization, diamond has become a strong candidate for use in electrochemical, electronic and biomedical applications. In this thesis, theoretical calculations have been used with the purpose to investigate various properties of the diamond surfaces.

    The effect of doping elements (N and B) on the stability of different surface terminations with X (where X = H, OH, Oontop or Obridge) has been investigated for a diamond (100) surface. As a result, the adsorption energy for all termination types was shown to decrease from the situation with a non-doped diamond surface, to the scenario with a N- (or B-doped) diamond thin film.. This result was found to correlate well with the changes of the calculated Csurface-X bond lengths. Furthermore, the spin density has been calculated and used to show the local distribution of the unpaired electron, which is the consequence of the introduction of dopants into the diamond slab. As a result, the spin density was found to be localized in the vicinity to the dopants for H- (or OH-) terminated diamond (100) surfaces. On the other hand, a delocalised spin density over the Oadsorbate and Csurface layer for Oontop- and Obridge-terminated surfaces, has also been observed. Moreover, the results of the pDOS calculations indicate the electron donating ability of N, and the hole donating ability of B. The Fermi level was shifted towards the lower conduction band edge for N-doped diamond, and towards the upper edge of the valence band edge for B-doped diamond. Hence, N-doped diamond will render n-type conductivity, and B-doped diamond will show p-type conductivity. In addition, an interesting observation was made for Oontop –terminated diamond surfaces. Localized electron conductivity, involving only this type of termination situation,, was also observed for N- (or B-) doped and completely  Oontop-terminated diamond surfaces.

    With the purpose of applying diamond substrates in the formation of epitaxial graphene, the annealing process of an ideal diamond (111) surface has also been simulated in the present work. It was thereby shown that high temperatures (over 2000 K) will be required for the epitaxial formation of graphene ontop of the diamond (111) surface. However, in the presence of hydrogen radicals (by saturating the radical sites in the system), the required temperature was observed to decrease to 1000 K. In addition to these MD simulations, by using an interlayer iron ontop of the diamond (111) surface, the adhesion energies between the graphene and the Fe//diamond slab, as well as the adhesion energy between the graphene//Fe layer and the diamond (111) surface, have been calculated. Thereby, the interaction between the graphene and Fe layer was obtained to be very weak, and of an electrostatic type. On the other hand, the interaction between the Fe interlayer and the diamond substrate was calculated as a moderately strong covalent bond. Moreover, the changes in these interactions, correlating to the changes in the pDOS spectra of graphene, Fe and diamond, gave a tendency of one-dimensional quantum size effect, depending on the thickness of Fe interlayer.

    List of papers
    1. A Theoretical Study of the Effect of Dopants on Diamond (100) Surface Stabilization for Different Termination Scenarios
    Open this publication in new window or tab >>A Theoretical Study of the Effect of Dopants on Diamond (100) Surface Stabilization for Different Termination Scenarios
    2015 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 5, p. 2545-2556Article in journal (Refereed) Published
    Abstract [en]

    The effect of dopants (N or B) on differently terminated diamond (100)-2 × 1 surfaces has in the present study been studied theoretically by using DFT (density functional theory) under periodic boundary conditions. The terminating species, X, include H, OH, Oontop, and Obridge. As a result of geometry optimization, the C–N and C–B bond lengths were calculated to be longer than for the situation with saturated binding conditions (i.e., the situation where N (or B) are binding to three other atoms, instead of four). Moreover, the X–Csurface-dopant angles were observed to decrease for the N-doped and increase for the B-doped senarios. In addition, the atomic charges and bond populations for the region surrounding the dopants were also carefully analyzed in order to compare the surface stabilization situations for non-, N- and B-doped diamond surfaces. For the H-terminated diamond surfaces, the C–H bonds became weakened when substituationally doped with either N or B. For the O-terminated diamond surfaces (i.e., both Oontop, and Obridge), the results showed opposite trends by strengthening (or weakening) the C–O bonds for the N- (or B-) doped system, respectivly. The adsorption energies for the various terminating species were observed to decrease when going from a nondoped to an N-doped situation and finally over to a B-doped situation. This is a result that strongly correlates with the calculated Csurface–X (X = H, OH, Oontop, Obridge) bond lengths. In addition, the effect of surface termination on the diamond surface stabilization energy, was observed to be in the following order: Obridge > Otop > H > OH. This result was valid for both non-, N- and B-doped diamond surfaces. The calculated spin density calculations indicated a local distribution of the unpaired electron in the N- and B-doped systems, respectively. This is a result that showed a strong correlation to the bond lengths surrounding the dopants and to the calculated adsorption energies for the terminating species, X. Moreover, the surface electronic structures (i.e., surface states) for the N- and B-doped systems were calculated and visualized by performing pDOS calculations. The results showed a shift of the Fermi levels for the N- and B-doped situations. As expected, the Fermi level was shifted toward the conduction band for the N-doped surfaces and toward the valence band for the B-doped systems. In addition, the pDOS spectra for the Oontop-termination showed extra states around the Fermi level, which were the result induced by the radical nature of this type of termination species.

    Place, publisher, year, edition, pages
    Washington, DC: , 2015
    Keywords
    Diamond, surface terminations, dopants
    National Category
    Materials Chemistry
    Research subject
    Chemistry with specialization in Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-242826 (URN)10.1021/jp511077v (DOI)000349136400035 ()
    Projects
    MATCON
    Funder
    EU, FP7, Seventh Framework Programme, MATCON-238201
    Available from: 2015-02-02 Created: 2015-02-02 Last updated: 2017-12-05Bibliographically approved
    2. Formation Conditions for Epitaxial Graphene on Diamond (111) Surfaces
    Open this publication in new window or tab >>Formation Conditions for Epitaxial Graphene on Diamond (111) Surfaces
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The phase transformation from a non-terminated diamond (111) surface to graphene has in the present study been simulated by using ab initio MD calculations at different temperatures and under various reaction conditions. For strict vacuum conditions, the graphitization process was observed to start at about 800 K, with a final graphene-like adlayer obtained at 2500 K. The C-C bonds across the interface were found to be broken gradually with an increase in temperature. The resulting graphene-like adlayer at 2500 K was observed to chemisorb to the underlying diamond surface with 33% of the initial C-C bonds, and with a C-C covalent energy value of 3.4 eV. The corresponding DOS spectra showed a p-doped character, as compared with graphene.

    When introducing H radicals during the annealing process, a graphene-like adlayer started to be formed at a much lower temperature; 500K. The completeness of the diamond-to-graphene process was found to strongly depend on the concentration of H radicals. When introducing a larger concentration of H radicals into the lattice in the initial part of the annealing process, the formation of a free-standing graphene layer was observed to take place at an even lower H concentration and temperature (1000 K). 

    Keywords
    Diamond, graphene, graphitization, theory, Molecular Dynamics, DFT
    National Category
    Materials Chemistry
    Research subject
    Chemistry with specialization in Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-242877 (URN)
    Projects
    MATCON
    Funder
    EU, FP7, Seventh Framework Programme, MATCON-238201
    Available from: 2015-02-02 Created: 2015-02-02 Last updated: 2015-04-17
    3. A Theoretical Study of Dye Molecules Adsorbed onto Diamond (111) Surfaces
    Open this publication in new window or tab >>A Theoretical Study of Dye Molecules Adsorbed onto Diamond (111) Surfaces
    2016 (English)In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 213, no 8, p. 2105-2111Article in journal (Refereed) Published
    Abstract [en]

    The combinations of different dye molecules adsorbed on 100% H-terminated B-doped diamond (111) surfaces, have been carefully simulated by using DFT under periodic boundary conditions. The dye molecules include C20H13NO3S4, C35H37NO2S3, C34H38OS2, C32H36OS2, and C31H35S3Br. The functional group within these dyes, behaves as an electron acceptor during the sunlight harvesting process. By comparing the upper valence band edge of the diamond surface with the HOMO and LUMO levels of the dyes in an energy diagram, a suitable scheme for a p-type dye sensitized solar cell was constructed. These functionalities were further confirmed by the observation of a partial degree of electron transfer from the diamond surface to the dye molecules. The combination of spectra for the dye molecules showed a wide absorption range from 200nm to 620nm. The effect of B doping on the binding of the dye molecules have furthermore been investigated. Shorter diamond//dye bonds are well correlated with large electron bond populations, and a larger degree of electron transfer. The former is regarded to be a meassure of covalency, and the latter a meassure of ionicity, in the interfacial bond. 

    Keywords
    B-doped diamond, DSSC, dye, DFT
    National Category
    Materials Chemistry
    Research subject
    Chemistry with specialization in Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-242878 (URN)10.1002/pssa.201600154 (DOI)000385223900014 ()
    Projects
    MATCON
    Funder
    EU, FP7, Seventh Framework Programme, MATCON-238201
    Note

    Title in Thesis list of papers: A Theoretical Study of Dye Molecules Adsorbed onto Diamond (111) Surfaces for the Application of a p-Type Dye Sensitized Solar Cell

    Available from: 2015-02-02 Created: 2015-02-02 Last updated: 2017-12-05Bibliographically approved
    4. Theoretical Study of the Effect of an Fe Interlayer on the Formation of Graphene on Diamond (111) surface
    Open this publication in new window or tab >>Theoretical Study of the Effect of an Fe Interlayer on the Formation of Graphene on Diamond (111) surface
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    The effect by a catalytic Fe interlayer on the formation of graphene onto a diamond (111) substrate, has been studied by using DFT calculations under perodict boundary conditions.  With varying the Fe interlayer thickness from two to five atomic layers, geometry optimized diamond//Fe//graphene multilayer models were obtained. A general result was that the Fe atoms are ontop positioned on both the graphene carbon atoms and on the diamond carbon atoms. Moreover, both the interfacial diamond//Fe and Fe//graphene adhesion energies were calculated and compared. As a result, the interaction between graphene and the iron layer, which was indentified as of an electrostatic nature, was found to be weak (-12.3 to -10.5 kJ/mol  per graphene C atom) and propotional to the thickness of the Fe layer. The thicker the Fe interlayer, the stronger was the adhesion energy. On the contary, the adhesion energy between the diamond substrate and the Fe layer was calculated as much stronger (-124.5 to -109.0 kJ/mol per diamond C atom), and following an inverse correlation. The thicker the Fe interlayer, the weaker is the interfacial adhesion energy. Calculations of electron density differences and partial Density of States (pDOS´s), will further support the results of a quantum size effect of the iron layer. 

    Keywords
    Graphitization, Graphene, Diamond (111), Fe catalysis, DFT
    National Category
    Materials Chemistry
    Research subject
    Chemistry with specialization in Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-242879 (URN)
    Projects
    MATCON
    Funder
    EU, FP7, Seventh Framework Programme, MATCON-238201
    Available from: 2015-02-02 Created: 2015-02-02 Last updated: 2019-03-21
  • 434.
    Song, Yang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Larsson, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    A Theoretical Study of Dye Molecules Adsorbed onto Diamond (111) Surfaces2016In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 213, no 8, p. 2105-2111Article in journal (Refereed)
    Abstract [en]

    The combinations of different dye molecules adsorbed on 100% H-terminated B-doped diamond (111) surfaces, have been carefully simulated by using DFT under periodic boundary conditions. The dye molecules include C20H13NO3S4, C35H37NO2S3, C34H38OS2, C32H36OS2, and C31H35S3Br. The functional group within these dyes, behaves as an electron acceptor during the sunlight harvesting process. By comparing the upper valence band edge of the diamond surface with the HOMO and LUMO levels of the dyes in an energy diagram, a suitable scheme for a p-type dye sensitized solar cell was constructed. These functionalities were further confirmed by the observation of a partial degree of electron transfer from the diamond surface to the dye molecules. The combination of spectra for the dye molecules showed a wide absorption range from 200nm to 620nm. The effect of B doping on the binding of the dye molecules have furthermore been investigated. Shorter diamond//dye bonds are well correlated with large electron bond populations, and a larger degree of electron transfer. The former is regarded to be a meassure of covalency, and the latter a meassure of ionicity, in the interfacial bond. 

  • 435.
    Song, Yang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Larsson, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    A Theoretical Study of the Effect of Dopants on Diamond (100) Surface Stabilization for Different Termination Scenarios2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 5, p. 2545-2556Article in journal (Refereed)
    Abstract [en]

    The effect of dopants (N or B) on differently terminated diamond (100)-2 × 1 surfaces has in the present study been studied theoretically by using DFT (density functional theory) under periodic boundary conditions. The terminating species, X, include H, OH, Oontop, and Obridge. As a result of geometry optimization, the C–N and C–B bond lengths were calculated to be longer than for the situation with saturated binding conditions (i.e., the situation where N (or B) are binding to three other atoms, instead of four). Moreover, the X–Csurface-dopant angles were observed to decrease for the N-doped and increase for the B-doped senarios. In addition, the atomic charges and bond populations for the region surrounding the dopants were also carefully analyzed in order to compare the surface stabilization situations for non-, N- and B-doped diamond surfaces. For the H-terminated diamond surfaces, the C–H bonds became weakened when substituationally doped with either N or B. For the O-terminated diamond surfaces (i.e., both Oontop, and Obridge), the results showed opposite trends by strengthening (or weakening) the C–O bonds for the N- (or B-) doped system, respectivly. The adsorption energies for the various terminating species were observed to decrease when going from a nondoped to an N-doped situation and finally over to a B-doped situation. This is a result that strongly correlates with the calculated Csurface–X (X = H, OH, Oontop, Obridge) bond lengths. In addition, the effect of surface termination on the diamond surface stabilization energy, was observed to be in the following order: Obridge > Otop > H > OH. This result was valid for both non-, N- and B-doped diamond surfaces. The calculated spin density calculations indicated a local distribution of the unpaired electron in the N- and B-doped systems, respectively. This is a result that showed a strong correlation to the bond lengths surrounding the dopants and to the calculated adsorption energies for the terminating species, X. Moreover, the surface electronic structures (i.e., surface states) for the N- and B-doped systems were calculated and visualized by performing pDOS calculations. The results showed a shift of the Fermi levels for the N- and B-doped situations. As expected, the Fermi level was shifted toward the conduction band for the N-doped surfaces and toward the valence band for the B-doped systems. In addition, the pDOS spectra for the Oontop-termination showed extra states around the Fermi level, which were the result induced by the radical nature of this type of termination species.

  • 436.
    Song, Yang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Larsson, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Theoretical Study of the Effect of an Fe Interlayer on the Formation of Graphene on Diamond (111) surfaceManuscript (preprint) (Other academic)
    Abstract [en]

    The effect by a catalytic Fe interlayer on the formation of graphene onto a diamond (111) substrate, has been studied by using DFT calculations under perodict boundary conditions.  With varying the Fe interlayer thickness from two to five atomic layers, geometry optimized diamond//Fe//graphene multilayer models were obtained. A general result was that the Fe atoms are ontop positioned on both the graphene carbon atoms and on the diamond carbon atoms. Moreover, both the interfacial diamond//Fe and Fe//graphene adhesion energies were calculated and compared. As a result, the interaction between graphene and the iron layer, which was indentified as of an electrostatic nature, was found to be weak (-12.3 to -10.5 kJ/mol  per graphene C atom) and propotional to the thickness of the Fe layer. The thicker the Fe interlayer, the stronger was the adhesion energy. On the contary, the adhesion energy between the diamond substrate and the Fe layer was calculated as much stronger (-124.5 to -109.0 kJ/mol per diamond C atom), and following an inverse correlation. The thicker the Fe interlayer, the weaker is the interfacial adhesion energy. Calculations of electron density differences and partial Density of States (pDOS´s), will further support the results of a quantum size effect of the iron layer. 

  • 437.
    Song, Yang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Yang, Nianjun
    University of Siegen.
    Nebel, Christoph
    Fraunhofer Institute IAF.
    Larsson, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Formation Conditions for Epitaxial Graphene on Diamond (111) SurfacesManuscript (preprint) (Other academic)
    Abstract [en]

    The phase transformation from a non-terminated diamond (111) surface to graphene has in the present study been simulated by using ab initio MD calculations at different temperatures and under various reaction conditions. For strict vacuum conditions, the graphitization process was observed to start at about 800 K, with a final graphene-like adlayer obtained at 2500 K. The C-C bonds across the interface were found to be broken gradually with an increase in temperature. The resulting graphene-like adlayer at 2500 K was observed to chemisorb to the underlying diamond surface with 33% of the initial C-C bonds, and with a C-C covalent energy value of 3.4 eV. The corresponding DOS spectra showed a p-doped character, as compared with graphene.

    When introducing H radicals during the annealing process, a graphene-like adlayer started to be formed at a much lower temperature; 500K. The completeness of the diamond-to-graphene process was found to strongly depend on the concentration of H radicals. When introducing a larger concentration of H radicals into the lattice in the initial part of the annealing process, the formation of a free-standing graphene layer was observed to take place at an even lower H concentration and temperature (1000 K). 

  • 438. Srinath, Aishwarya
    et al.
    von Fieandt, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lindblad, Rebecka
    Fritze, Stefan
    Korvela, Markus
    Petersson, Jean
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Nyholm, Leif
    Corrosion in Al-Cr-Nb-Y-Zr-N multi-component alloys: What role does the nitrogen content play?Manuscript (preprint) (Other academic)
  • 439. Srivastava, Leena
    et al.
    Tundup, Smanla
    Choi, Beak-San
    Norberg, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Harn, Donald
    Immunomodulatory Glycan Lacto-N-Fucopentaose III Requires Clathrin-Mediated Endocytosis To Induce Alternative Activation of Antigen-Presenting Cells2014In: Infection and Immunity, ISSN 0019-9567, E-ISSN 1098-5522, Vol. 82, no 5, p. 1891-1903Article in journal (Refereed)
    Abstract [en]

    The mechanism of alternative activation of antigen-presenting cells (APCs) is largely unknown. Lacto-N-fucopentaose III (LNFPIII) is a biologically conserved pentasaccharide that contains the Lewis(x) trisaccharide. LNFPIII conjugates and schistosome egg antigens, which contain the Lewisx trisaccharide, drive alternative activation of APCs and induce anti-inflammatory responses in vivo, preventing inflammation-based diseases, including psoriasis, transplant organ rejection, and metabolic disease. In this study, we show that LNFPIII conjugates and schistosome egg antigens interact with APCs via a receptor-mediated process, requiring internalization of these molecules through a clathrin/dynamin-dependent but caveolus-independent endocytic pathway. Using inhibitors/small interfering RNA (siRNA) against dynamin and clathrin, we show for the first time that endocytosis of Lewis(x)-containing glycans is required to drive alternative maturation of antigen-presenting cells and Th2 immune responses. We identified mouse SIGNR-1 as a cell surface receptor for LNFPIII conjugates. Elimination of SIGNR-1 showed no effect on uptake of LNFPIII conjugates, suggesting that other receptors bind to and facilitate uptake of LNFPIII conjugates. We demonstrate that disruption of actin filaments partially prevented the entry of LNFPIII conjugates into APCs and that LNFPIII colocalizes with both early and late endosomal markers and follows the classical endosomal pathway leading to lysosome maturation. The results of this study show that the ability of LNFPIII to induce alternative activation utilizes a receptor- mediated process that requires a dynamin-dependent endocytosis. Thus, key steps have been defined in the previously unknown mechanism of alternative activation that ultimately leads to induction of anti-inflammatory responses.

  • 440.
    Strömme, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Mihranyan, Albert
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    COMPOSITE MATERIALS INCLUDING AN INTRINSICALLY CONDUCTING POLYMER, AND METHODS AND DEVICES2014Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A composite material in the form of a continuous structure comprises an intrinsically conducting polymer (ICP) layer coated on a substrate, the composite material having a surface area of at least 0.1 m2/g, at least 1 m2/g, or at least 5 m2/g. Methods of manufacturing the composite material comprise coating the substrate with a layer of the intrinsically conducting polymer. Electrochemical or electrical devices comprise at least one component formed of the composite material.

  • 441.
    Strömme, Maria
    et al.