uu.seUppsala universitets publikationer
Ändra sökning
Avgränsa sökresultatet
26272829 1401 - 1425 av 1425
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1401. Zadin, Vahur
    et al.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Modelling polymer electrolytes for 3D-microbatteries using finite element analysis2011Ingår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 57, s. 237-243Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Comparisons between a LiPF(6)center dot PEO(20) polymer electrolyte and a 1.5 M LiPF(6) liquid electrolyte in a 3D-microbattery of coated interdigitated current collector pillars is presented here, using Finite Element Analysis (FEA). Ionic transport in the electrolyte is modeled by the Nernst-Planck equation and electrode potentials by Ohm's law. Simulations were carried out in steady state. The height of the electrode pillars and the distance between them were systematically varied in the simulations to evaluate the effects on ionic transport in terms of concentration, concentration gradient and the minimum concentration in the electrolyte. The studies showed that the polarization in the electrolyte can be decreased by increasing the electrode pillar length, while increasing electrode distances led to a nonuniformity of the electrochemical activity. Indications of an optimum pillar length were also observed. Comparisons of the electrolytes showed that the polymer electrolyte was able to deliver a more uniform electrochemical activity for these cell designs, but not able to sustain as high currents as the liquid electrolytes. At the current density used (10 A/m(2)), concentration polarization in the polymer electrolyte led to concentration deviations from the mean value of up to 60%.

  • 1402.
    Zadin, Vahur
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Kasemaegi, Heiki
    Aabloo, Alvo
    Thomas, John O.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Finite element modelling of ion transport in the electrolyte of a 3D-microbattery2011Ingår i: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 192, nr 1, s. 279-283Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A mathematical model describing ionic transport in a 3D-microbattery (3D-MB) electrolyte is developed here using finite element methodology. The model is then exploited to study a 3D-MB based on an interdigitated plate ("trench") architecture for a 10 pm-thick electrolyte layer separating 10 mu m-thick graphite anode and LiCoO(2) cathode plates. The effect of varying plate length, end-shape and electronic conductivity is also modelled. It is shown that the 3D-MB architecture gives rise to qualitatively non-uniform current densities, leading to sub-optimal surface utilization. This can, in turn, be optimized by varying electrode geometries and/or material properties.

  • 1403. Zadin, Vahur
    et al.
    Kasemägi, Heiki
    Aabloo, Alvo
    Brandell, Daniel
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Modelling electrode material utilization in the trench model 3D-microbattery by finite element analysis2010Ingår i: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 195, nr 18, s. 6218-6224Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A mathematical model for ionic transport in 3D-microbattery (3D-MB) using finite element analysis is presented here, based on concentrated solution theory, ionic and atomic diffusion and the Butler-Volmer equation. The model is used to study electrochemical processes taking place in the electrodes and electrolyte of a 3D-MB in the trench architecture, with a 10 mu m thick electrolyte layer separating 10 mu m thick graphite anode and LiCoO2 cathode plates. The effect of changing conductivity of the positive electrode and the electrode plate height is also studied. Qualitative and quantitative data describing battery performance in terms of concentration gradient development and discharge curves points out the range for the most favourable electronic conductivity values of the electrodes: the values should not differ by more than order of magnitude. Furthermore, it is shown that also with optimal electrode conductivity values for electrodes, the Li ion diffusion in the electrodes during discharge is limiting the performance of the battery due to inhomogeneous lithiation and delithiation. Changing electrode height can be used to fine tune surface area usage, but has a limited effect on the overall battery performance.

  • 1404. Zavodnik, Valery E.
    et al.
    Ivanov, Sergey A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Stash, Adam I.
    alpha-lead tellurite from single-crystal data2008Ingår i: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 64, s. I16-U10Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The crystal structure of the title compound, alpha-PbTeO3 ( PTO), has been reported previously by Mariolacos [ Anz. Oesterr. Akad. Wiss. Math. Naturwiss. Kl. ( 1969), 106, 128-130], refined on powder data. The current determination at room temperature from data obtained from single crystals grown by the Czochralski method shows a significant improvement in the precision of the geometric parameters when all atoms have been refined anisotropically. The selection of a centrosymmetric (C2/c) structure model was confirmed by the second harmonic generation test. The asymmetric unit contains three formula units. The structure of PTO is built up of three types of distorted [PbOx] polyhedra (x=7 and 9) which share their O atoms with TeO3 pyramidal units. These main anionic polyhedra are responsible for establishing the two types of tunnel required for the stereochemical activity of the lone pairs of the Pb2+ and Te4+ cations.

  • 1405. Zavodnik, Valery E.
    et al.
    Ivanov, Sergey A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Stash, Adam I.
    On the thermal evolution of the crystal structure of SrTeO3. Part III. The gamma-phase of SrTeO3 at 583 K2007Ingår i: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 63, nr 7, s. I151-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As a part of current systematic investigations of strontium tellurite, SrTeO3, with particular emphasis on crystal chemistry and phase transitions, the structure of the gamma phase has been determined at 583 K using a single-crystal analysis. Both structural and nonlinear optical measurements indicate a beta-gamma first-order phase transition temperature that is close to 563 K. The structure of the gamma phase is monoclinic (C2) and does not differ essentially from the alpha phase (C2). Comparison of the alpha and gamma structures shows that the main atomic shifts and tiltings are connected with Te4, Te5 and Te6 pyramids.

  • 1406. Zavodnik, Valery E.
    et al.
    Ivanov, Sergey A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Stash, Adam I.
    On the thermal evolution of the crystal structure of SrTeO3: the beta-form at 473 K2007Ingår i: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 63, nr 4, s. I111-I112Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As part of a programme to study structural phase transitions in strontium tellurite, SrTeO3, (STO), the structure of the beta-form has been determined at 473 K using single-crystal analysis. Both the structural and non-linear optical measurements indicate an alpha-beta first-order phase-transition temperature that is close to 363 K on heating and 308 K on cooling. The structure of the beta-phase is monoclinic (C2/c) and does not differ essentially from the alpha-phase (C2) configuration. During the alpha-beta phase transition there is a slight rearrangement of the cation building blocks [n-vertex SrOn polyhedra (n = 6, 7 or 8) and TeO3 pyramids]; this phase transformation can be described by a displacive mechanism.

  • 1407. Zavodnik, Valery E.
    et al.
    Ivanov, Sergey A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Stash, Adam I.
    The alpha-phase of SrTeO3 at 295 K2007Ingår i: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 63, s. i75-i76Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The crystal structure of strontium tellurite (STO), SrTeO3, has been determined at room temperature using X-ray diffraction data obtained from single crystals grown by the Czochralski method. Selection of a non-centrosymmetric (C2) structure model was confirmed by the second harmonic generation test. The structure of STO is built up of three types of distorted [SrOx] polyhedra (x = 6, 7 and 8) which share their oxygen anions with TeO3 pyramidal units. These main anionic polyhedra are responsible for establishing two types of tunnels required for the electron lone pairs of the Te4+ cation.

  • 1408. Zavodnik, Valery E.
    et al.
    Ivanov, Sergey A.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Stash, Adam I.
    The delta-phase of SrTeO3 at 780 K2008Ingår i: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 64, s. I52-U75Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As part of a structural investigation of strontium tellurate(IV) (STO), SrTeO3, with particular emphasis on the crystal chemistry and phase transitions, the structure of the delta-phase has been determined at 780 K using a single-crystal analysis. Both structural and non-linear optical measurements indicate that STO undergoes a gamma -> ;delta second-order ferroelectric phase transition at 633 K from the C2 (gamma) to the C2/m (delta) modification. Systematic differences between the similar gamma- and delta-phase structures were determined and it was found that this phase transformation can be described by a displacive mechanism.

  • 1409. Zettersten, C
    et al.
    Bökman, C. F.
    Sjöberg, P. J. R.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    A Novel Set-Up for the Coupling of a Thin Layer Electrochemical Cell to Electrospray Mass Spectrometry2003Ingår i: presented at the 16th International Mass Spectrometry Conference (IMSC), Edinburgh, August 31 - September 5, 2003, 2003Konferensbidrag (Refereegranskat)
  • 1410. Zettersten, C
    et al.
    Sjöberg, P. J. R.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    The Reaction Mechanism of 4-Chloroaniline studied by Cyclic Voltammetry and Electrochemistry coupled to Electrospray Ionisation Mass Spectrometry2008Ingår i: presented at the 18th Analysdagarna (The Analytical Days), Göteborg, 16-18 June, 2008., 2008Konferensbidrag (Refereegranskat)
  • 1411.
    Zettersten, Camilla
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Co, Michelle
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Wende, Sandra
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Turner, Charlotta
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Sjöberg, Per J. R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi, Analytisk kemi.
    Identification and Characterization of Polyphenolic Antioxidants Using On-Line Liquid Chromatography, Electrochemistry, and Electrospray Ionization Tandem Mass Spectrometry2009Ingår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 81, nr 21, s. 8968-8977Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is demonstrated that electrochemistry (EC) coupled to liquid chromatography (LC) and electrospray ionization tandem mass spectrometry (LC/EC/ESI-MS/MS) can be used to rapidly obtain information about the antioxidant activity (i.e., oxidation potential) and capacity (i.e., amount) of polyphenolic compounds, including catechin, kaempferol, resveratrol, quercetin, and quercetin glucosides. The described on-line LC/EC/ESI-MS/MS method facilitates the detection and characterization of individual antioxidants based on a combination of the obtained m/z values for the antioxidants and their oxidation products, the potential dependences for the ion intensities, and correlations between the retention times in the LC, EC, and MS chromatograms. As these results provide patterns that can be used in rapid screening for antioxidants in complex samples, the method should be a valuable complement to chemical assays commonly used to determine the total antioxidant capacity of samples. It is shown that the antioxidant capacity for a mixture of polyphenolic compounds depends on the redox potential employed in the evaluation, and this should consequently be taken into account when comparing results from different total antioxidant capacity assays. It is also demonstrated that the inherent antioxidant capacities of phenolic compounds increase with an increasing number of hydroxyl groups and that the potential needed to oxidize the remaining hydroxyl groups increases successively upon oxidation of the compound. Unlike chemical assays, which generally do not provide any information about the identities of the compounds on the molecular level, the present screening method can be used to identify individual antioxidants, rank compounds with respect to their ease of oxidation, and to study the antioxidant capacity at any redox potential of interest.

  • 1412.
    Zettersten, Camilla
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Kemiska institutionen, Avdelningen för analytisk kemi.
    Lomoth, Reiner
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Hammarström, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Fysikalisk-kemiska institutionen.
    Sjöberg, Per
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Kemiska institutionen, Avdelningen för analytisk kemi.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    The influence of the thin-layer flow cell design on the mass spectra when coupling electrochemistry to electrospray ionisation mass spectrometry2006Ingår i: Journal of Electroanalytical Chemistry, ISSN 0022-0728, E-ISSN 1873-2569, Vol. 590, nr 1, s. 90-99Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of the flow cell configuration on the mass spectra obtained when coupling an electrochemical thin-layer flow cell to electrospray mass spectrometry (ESI-MS) has been investigated. It is shown that interferences due to the electrochemical reaction on the counter electrode and/or the absence of 100% conversion efficiency can alter the mass spectra when conventional thin-layer flow cells are used in conjunction with ESI-MS. The effects, which affect the intensities and distribution of the peaks in the mass spectra, can result in the inability to detect products formed at the working electrode. Comparisons of mass spectra, generated after the electrochemical oxidation of a dinuclear Mn complex (where bpmp = 2,6-bis[bis(2-pyridylmethyl) amino]methyl-4-methylphenol) using two different thin-layer flow cells clearly show that the potential dependence and appearance of the mass spectra depend on the flow cell configuration used. The use of a modified thin-layer flow cell, in which the counter electrode had been separated from the working electrode, gave rise to significantly increased intensities for the oxidised MnIII,IV state of the complex. With the conventional unmodified cell, the corresponding complex was only seen for considerably higher oxidation potentials. The different results can be explained by the reduced risk of redox cycling and interferences due to species generated at the counter electrode with the modified cell. As interferences due to the counter electrode reactions likewise may be expected with many coulometric flow cells, the electrochemical cell design clearly needs to be considered when using electrochemistry coupled to ESI-MS to study electrochemical reactions.

  • 1413.
    Zettersten, Camilla
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi.
    Sjöberg, Per J. R.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi.
    Nyholm, Leif
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Oxidation of 4-chloroaniline studied by on-line electrochemistry electrospray ionization mass spectrometry2009Ingår i: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 81, nr 13, s. 5180-5187Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The oxidation of 4-chloroaniline (4-CA) has been studied by electrochemistry (EC) coupled on-line with electrospray ionization mass spectrometry (ESI-MS) using two electrochemical flow cells of different design. The experimental results, which generally verify previously suggested oxidation pathways for 4-CA, also indicate the presence of a so far unrecognized comproportionation reaction. The oxidation of 4-CA (m/z 128.2) was found to give rise to the formation of both an oxidized dimer, 4-[(4-chlorophenyl)imino]-2,5-cyclohexadien-1-imine (m/z 217.2) and a reduced dimer, 4-amino-4’-chlorodiphenylamine (m/z 219.2), in addition to a dimer intermediate (m/z 253.2). This unexpected formation of the reduced dimer is shown to stem from a comproportionation reaction involving 4-CA and the oxidized dimer. The presence of the latter reaction was clearly seen by comparing results obtained with two thin-layer flow cells, both with conversion efficiencies of 50% but of different design, with respect to the influence of the counter electrode reaction on the reaction at the working electrode. The experimental results demonstrate that the formation of the reduced dimer is favored by a decrease in the local pH in the flow cell and the influence of the pH on the oxidation of 4-CA was also investigated in the pH range between 2.0 and 6.0 using off-line voltammetry. It is concluded that EC/ESI-MS is a powerful tool for the study of the present type of reactions and that studies on reaction pathways are best carried out with thin-layer flow cells having conversion efficiencies smaller than 100% as this facilitates the detection of reaction intermediates. Comproportionation reactions, similar to the reaction present in the 4-CA system, can also be expected to be present during the formation of conducting polymers such as polyaniline and polypyrrole.

  • 1414.
    Zhu, Jiefang
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi.
    Zach, Michael
    Nanostructured materials for photocatalytic hydrogen production2009Ingår i: Current Opinion in Colloid & Interface Science, ISSN 1359-0294, E-ISSN 1879-0399, Vol. 14, nr 4, s. 260-269Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Photocatalytic hydrogen (H-2) production represents a very promising but challenging contribution to a clean, sustainable and renewable energy system. The photocatalyst material plays a key role in photocatalytic H-2 production, and it has proven difficult to obtain corrosion resistant, chemically stable, visible light harvesting and highly efficient photocatalysts, which have their band edges matching the O-2 and H-2 production levels. Nanoscience and nanotechnology are opening a new vista in the development of highly active, nanostructured photocatalysts with large surface areas for optimized light absorption, minimized distances (or times) for charge-carrier transport, and further favorable properties. Our focus here is on recently developed nanostructured photocatalysts. In particular. the particle size, chemical composition (including dopants), microstructure, crystal phase. morphology, surface modification, bandgap and flat-band potential of the nanophotocatalysts have shown a visible effect on photocatalytic H-2 production rates, which may be further increased by adding sensitizers, cocatalysts or scavengers. Finally, potential directions required to push this research field a step further are highlighted.

  • 1415. Zhukovskii, Yu.F.
    et al.
    Kotomin, E.A.
    Herschend, Björn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi. strukturkemi.
    Hermansson, Kersti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi. strukturkemi.
    Jacobs, P.W.M.
    A first-principles study of the Ag7A12O3(0001) interface.2001Ingår i: Int. J. Mol. Sci., Vol. 2, s. 271-Artikel i tidskrift (Refereegranskat)
  • 1416. Zhukovskii, Yu.F
    et al.
    Kotomin, E.A
    Herschend, Björn
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi. strukturkemi.
    Hermansson, Kersti
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi. strukturkemi.
    Jacobs, P.W.M
    The adhesion properties of the Ag/alfa -A12O3(0001) interface: an ab initio study.2002Ingår i: Surface Science, Vol. 513, s. 343-Artikel i tidskrift (Refereegranskat)
  • 1417.
    Zlotea, Claudia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Andersson, Yvonne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Microstructural modifications induced by hydrogen absorption in Mg5Ga2 and Mg6Pd2006Ingår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 54, nr 20, s. 5559-5564Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have recently proposed a new method to design one-dimensional structures of MgH2 in the nano- and micrometer ranges by hydrogen-induced disproportionation of bulk Mg24Y5. The present study confirms the same behavior in hydrogenated Mg5Ga2 and Mg6Pd. Single-crystalline one-dimensional structures and microparticles of MgH2 are formed by hydrogen absorption and subsequent partial disproportionation of Mg5Ga2 and Mg6Pd. The MgH2 whiskers and particles grow with different morphologies for different alloying partners. Growth mechanisms are proposed in relation to the morphology and the chemical surface composition of original compounds.

  • 1418.
    Zlotea, Claudia
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Lu, Jun
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Mikrostrukturlaboratoriet, MSL.
    Andersson, Yvonne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Formation of one-dimensional MgH2 nano-structures by hydrogen induced disproportionation2006Ingår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 426, nr 1-2, s. 357-362Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Remarkable formation of one-dimensional single crystalline MgH2 structures in the nano- and micro-meters ranges is reported. These structures have been tailored by hydrogen absorption and subsequent disproportionation of bulk Mg24Y5. The MgH2 whiskers have been structurally and morphologically characterized by X-rays diffraction, scanning and transmission electron microcopies. A growth model is proposed for the early stage of the whiskers formation by combining surface chemical and morphological investigations. The formation of MgH2 whiskers opens new engineering explorations and challenges for further experimental and theoretical studies.

  • 1419. Zlotea, Claudia
    et al.
    Sahlberg, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Moretto, Pietro
    Andersson, Yvonne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Hydrogen sorption properties of a Mg-Y-Ti alloy2010Ingår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 489, nr 2, s. 375-378Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The catalytic effect of titanium on the hydrogen sorption properties of a Mg–Y–Ti alloy has been investigated. The alloy is formed by a majority phase Mg24+xY5, a minor phase of solid solution of Y in Mg and Ti clusters randomly dispersed in the sample. During the first hydrogen absorption cycle 5.6 wt.% hydrogen was absorbed at temperatures above 613 K. The alloy decomposed almost completely to MgH2 and YH3. After hydrogen desorption pure Mg and YH2 were formed. For further absorption/desorption cycles the material had a reversible hydrogen capacity of 4.8 wt.%. The MgH2 decomposition enthalpy was determined to −68 kJ/mol H2, and the calculated activation energy of hydrogen desorption of MgH2 was 150(±10) kJ/mol.

  • 1420. Zlotea, Claudia
    et al.
    Sahlberg, Martin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Özbilen, Sedat
    Moretto, Pietro
    Andersson, Yvonne
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Hydrogen desorption studies of the Mg24Y5–H system: Formation of Mg tubes, kinetics and cycling effects2008Ingår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 56, nr 11, s. 2421-2428Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The current study focuses on the hydrogen desorption properties of hydrogenated Mg24Y5. Recently, we have reported the formation of unidirectional MgH2 structures by hydrogen absorption and induced disproportionation of Mg24Y5. During hydrogen desorption, a complex voiding phenomenon produces Mg tubes and carved particles with nano-sized walls. The selected area electron diffraction patterns demonstrate that the Mg tubes are single crystals. A harmonized picture of the unidirectional growth based on different Mg vapor models is proposed. The kinetic properties of hydrogen desorption are improved as compared with commercial MgH2. Hydrogenation/dehydrogenation cycling lowers the thermal stability of the hydrogen desorption at the expense of the total desorbed hydrogen capacity. Both whiskers and microparticles are depleted into clusters of nanoparticles after extensive cyclin

  • 1421.
    Åkesson, Eva
    et al.
    Lunds universitet.
    Elmgren, Maja
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för fysikalisk och analytisk kemi.
    Edström, Kristina
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Strukturkemi.
    Bologna and beyond: opportunities and obstacles.2008Ingår i: Chemistry International, ISSN 0193-6484, Vol. 30, nr 4, s. 13-15Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 1422.
    Ångström, Jonas
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Hydrogen absorption/desorption properties of the Sc(AlxNi1-x)2 system2011Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Sc(AlxNi1-x)2 is a pseudobinary C14 Laves phase and a potential interstitial hydrogen storage material or anode in a Ni-MH battery. A previous study showed that Sc1Al1Ni1 can store hydrogen reversibly; both interstitially and trough decomposition into ScH2 and AlNi. It is also known that the exact composition is very important for the hydrogen storage properties of pseudobinary Laves phases. This thesis work is aimed at synthesising Sc(AlxNi1-x)2 and study the effect of the Ni/Al ratio on the hydrogen absorption/desorption process as well as the interstitial storage capacity. Compositions with high nickel content had the highest capacity (at least 0.67wt% for ScAl0.66Ni1.34) and ones with high aluminium content had the lowest total storage capacity (0wt% for ScAl1.28Ni0.62). The former composition was also shown to absorb and desorb hydrogen during multiple cycles. Desorption of interstitial hydrogen from ScAl0.66Ni1.34 requires 4.6kJ/mol in activation energy.

    Ladda ner fulltext (pdf)
    fulltext
  • 1423. Öberg, Å.
    et al.
    Kassman, Åsa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    André, Benny
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Wiklund, Urban
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Lindquist, M.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Lewin, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Högberg, Hans
    Joelsson, T.
    Ljungcrantz, H.
    Conductive nanocomposite ceramics as tribological and electrical contact materials2010Ingår i: European Physical Journal: Applied physics, ISSN 1286-0042, E-ISSN 1286-0050, Vol. 49, nr 2, s. 22902-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Conductive ceramics have widespread use in many industrial applications. One important application for such materials is electrical contact technology. Over the last few years, a new class of nanocomposite ceramic thin film materials has been developed with contact coatings as one key objective. This family of materials has proven to combine the favorable contact properties of metals, such as low electrical and thermal resistivity, and high ductility, with those of ceramics such as low friction and wear rate, high chemical integrity and good high-temperature properties. Furthermore, it is also found that the tribological properties of such materials can be tailored by alloying thus creating a triboactive system. The technology is now industrialized, and a practical example of a contact system utilizing a nanocomposite coating for improved performance is given.

  • 1424. Öberg, Åke
    et al.
    Kassman Rudolphi, Åsa
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Wiklund, Urban
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    André, Benny
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Tillämpad materialvetenskap.
    Lewin, Erik
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Jansson, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi.
    Conductive nanocomposite ceramics as tribological and electrical contact materials2008Ingår i: International Conference on Electrical Contacts, ICEC 2008, 2008Konferensbidrag (Refereegranskat)
  • 1425. Östlund, L
    et al.
    Mattsson, A
    Leideborg, Mikael
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Westin, Gunnar
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi. Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Kemiska sektionen, Institutionen för materialkemi, Oorganisk kemi. oorganisk kemi.
    Photodecomposition of acetone on ZrOx-TiO2 thin films in O2 excess and deficit conditions2007Ingår i: 31st Int. Conf. Adv. Ceram. Comp. s7, 2007, s. 175-186Konferensbidrag (Refereegranskat)
26272829 1401 - 1425 av 1425
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf