Change search
Refine search result
1 - 7 of 7
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Nilsson, Johan O.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Leetmaa, Mikael
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Wang, B.
    Zguns, Pjotrs
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala University, Sweden.
    Pašti, I.
    Sandell, A.
    Skorodumova, Natalia
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala University, Sweden.
    Modeling Kinetics of Water Adsorption on the Rutile TiO2 (110) Surface: Influence of Exchange-Correlation Functional2018In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 255, no 3, article id 1700344Article in journal (Refereed)
    Abstract [en]

    The accuracy of the theoretical description of materials properties in the framework of density functional theory (DFT) inherently depends on the exchange-correlation (XC) functional used in the calculations. Here we investigate the influence of the choice of a XC functional (PBE, RPBE, PW91, and PBE0) on the kinetics of the adsorption, diffusion and dissociation of water on the rutile TiO2(110) surface using a combined Kinetic Monte Carlo (KMC) – DFT approach, where the KMC simulations are based on the barriers for the aforementioned processes calculated with DFT. We also test how the adsorption energy of intact and dissociated water molecules changes when dispersion interactions are included into the calculations. We consider the beginning of the water layer formation varying coverage up to 0.2 monolayer (ML) at temperatures up to 180 K. We demonstrate that the dynamics of the simulated water–titania system is extremely sensitive to the choice of the XC functional.

  • 2.
    Zguns, Pjotrs A.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Department of Physics and Astronomy, Uppsala University, Box 516, 75121 Uppsala, Sweden .
    Ruban, Andrei V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Materials Center Leoben Forschung GmbH, A-8700 Leoben, Austria.
    Skorodumova, Natalia
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Department of Physics and Astronomy, Uppsala University, Box 516, 75121 Uppsala, Sweden .
    Ordering and phase separation in Gd-doped ceria: a combined DFT, cluster expansion and Monte Carlo study2017In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 19, no 39, p. 26606-26620Article in journal (Refereed)
    Abstract [en]

    Ordering of dopants and oxygen vacancies is studied for Gd-doped ceria (x(Gd) <= 0.25) by means of a combined density functional theory (DFT) and cluster expansion approach, where the cluster interactions derived from DFT calculations are further used in Monte Carlo simulations. The methodology is meticulously tested and the stability of the obtained solutions with respect to the volume change, applied exchange-correlation approximation and other modelling parameters is carefully analysed. We study Gd and vacancy ordering in the case of thermodynamic equilibrium and vacancy ordering for quenched Gd configurations. We find that at the thermodynamic equilibrium there exists a transition temperature (T-C) below which phase separation into C-type Gd2O3 and pure CeO2 occurs. The phase separation is observed in the whole studied concentration range and the transition temperature increases with concentration from ca. 600 (x(Gd) = 0.03) to 1000 K (x(Gd) = 0.25). Above T-C the distribution of Gd is random, oxygen vacancies tend to cluster in the coordination shells along < 1, 1/2, 0 > and < 1, 1, 1 >, and the nearest neighbour position is preferred for Gd-vacancy. In the quenched Gd case, where Gd atoms are immobilised below 1500 K, the vacancy ordering is significantly frustrated. In fact, we observe an oxygen freezing transition below temperature T-F approximate to T-C - 350 K, which is close to temperatures at which a change in the conductivity slope is observed experimentally.

  • 3.
    Zguns, Pjotrs A.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala Univ, Dept Phys & Astron, Box 516, S-75121 Uppsala, Sweden.
    Ruban, Andrei V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Leoben Forsch GmbH, Mat Ctr, A-8700 Leoben, Austria..
    Skorodumova, Natalia V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala Univ, Dept Phys & Astron, Box 516, S-75121 Uppsala, Sweden.
    Phase diagram and oxygen-vacancy ordering in the CeO2-Gd2O3 system: a theoretical study2018In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 17, p. 11805-11818Article in journal (Refereed)
    Abstract [en]

    We present the phase diagram of Ce1-xGdxO2-x/2 (CGO), calculated by means of a combined Density Functional Theory (DFT), cluster expansion and lattice Monte Carlo approach. We show that this methodology gives reliable results for the whole range of concentrations (x x(Gd) <= 1). In the thermodynamic equilibrium, we observe two transitions: the onset of oxygen-vacancy (O-Va) ordering at ca. 1200-3300 K for concentrations x(Gd) = 0.3-1, and a phase separation into CeO2 and C-type Gd2O3 occurring below ca. 1000 K for all concentrations. We also model 'quenched' systems, with cations immobile below 1500 K, and observe that the presence of random-like cation configurations does not prevent C-type vacancy ordering. The obtained transition temperatures for Va ordering agree rather well with existing experimental data. We analyse the effect of vacancy ordering and composition on the lattice parameters and relaxation pattern of cations.

  • 4.
    Žguns, Pjotrs
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Multiscale Materials Modelling.
    First Principles Modelling of Clean Energy Materials2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This licentiate thesis presents the density functional theory study on clean energy materials relevant for catalysis applications, and for solid oxide fuel cells.

    In the first part of the thesis the metal supported ultrathin films, namely ScN/Mo, MgO/Mo and NaF/Mo are considered, and the Cu atom adsorption and charging on them is explored.The comparative study of these different films allows us to provide recommendations regarding the choice of materials, in order to promote adatom charging. The modulation of the adatom charge, by changing the material of the film, also paves the way for the design of novel catalysts. Moreover, the detailed investigation of the Cu/NaF/Mo caseshows a correlation between the charge redistribution upon the adsorption and the anharmonicity of the accompanying distortion. Overall, the research commands a fresh view on the adatom charging mechanism.

    In the second part of the thesis the gadolinium doped ceria, used asoxide electrolyte in solid oxide fuel cells, is studied. The employment of the cluster expansion method together with the density functional theory calculations provides the description of the configurational energy spectrum of dopants and oxygen vacancies in terms of effective pair and three site interactions. The chosen method allows one to predict the energy of anarbitrary configuration. Moreover, the effect of volume change on the strength of interactions is investigated, which is relevant for the modelling ofoxide electrolytes at operating temperatures of solid oxide fuel cells,i.e. when volume expansion is notable.

  • 5.
    Žguns, Pjotrs A.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala University, Sweden.
    Wessel, M.
    Skorodumova, Natalia V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala University, Sweden.
    Cu adatom charging on Mo supported ScN, MgO and NaF2015In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 114, p. 94436-94445Article in journal (Refereed)
    Abstract [en]

    Molybdenum supported thin films of ScN, MgO and NaF with a Cu adatom have been studied in the framework of density functional theory. We have observed a charge transfer from the metal/film interface to the Cu atom and investigated its relation to surface and interface deformations. We find that a weak interaction between the metal and the film is a promising prerequisite for adatom charging. The detailed study of Cu/NaF/Mo and NaF/Mo indicates that the distortion of the NaF film caused by the Cu adsorption has essentially anharmonic character, as it is coupled to a strong charge redistribution in the system. © 2015 The Royal Society of Chemistry.

  • 6.
    Žguns, Pjotrs
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Multiscale Materials Modelling.
    Skorodumova, Natalia
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Multiscale Materials Modelling. Uppsala University, Sweden.
    Ruban, Andrei
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Multiscale Materials Modelling.
    Gadolinium doped ceria: configurational energy spectrum and volume expansion effectManuscript (preprint) (Other academic)
  • 7.
    Žguns, Pjotrs
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Multiscale Materials Modelling.
    Wessel, Michael
    Faculty of Chemistry, University Duisburg-Essen, Universitätsstr. 5, 45141 Essen, Germany.
    Skorodumova, Natalia
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Multiscale Materials Modelling. Uppsala University, Sweden.
    Charging of Cu atom on Mo supported thin films of ScN, MgO, NaFManuscript (preprint) (Other academic)
1 - 7 of 7
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf