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Johansson, Börje
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Publications (10 of 277) Show all publications
Kholtobina, A. S., Forslund, A., Ruban, A. V., Johansson, B. & Skorodumova, N. V. (2023). Temperature dependence of (111) and (110) ceria surface energy. Physical Review B, 107(3), Article ID 035407.
Open this publication in new window or tab >>Temperature dependence of (111) and (110) ceria surface energy
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2023 (English)In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 107, no 3, article id 035407Article in journal (Refereed) Published
Abstract [en]

High-temperature properties of ceria surfaces are important for many applications. Here, we report the temperature dependencies of surface energy for (111) and (110) CeO2 obtained in the framework of the extended two-stage up-sampled thermodynamic integration using Langevin dynamics. The method was used together with machine-learning potentials called moment tensor potentials (MTPs), which were fitted to the results of the ab initio molecular dynamics calculations for (111) and (110) CeO2 at different temperatures. The parameters of MTP training and fitting were tested, and the optimal algorithm for the ceria systems was proposed. We found that the temperature increases from 0 to 2100 K led to the decrease of the Helmholtz free energy of (111) CeO2 from 0.78 to 0.64 J/m2. The energy of (110) CeO2 dropped from 1.19 J/m2 at 0 K to 0.92 J/m2 at 1800 K. We show that it is important to consider anharmonicity, as simple consideration of volume expansion gives the wrong temperature dependencies of the surface energies.

Place, publisher, year, edition, pages
American Physical Society, 2023
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-500326 (URN)10.1103/PhysRevB.107.035407 (DOI)000956927600002 ()
Funder
Swedish National Infrastructure for Computing (SNIC), SNIC 2021/3-36Swedish National Infrastructure for Computing (SNIC), SNIC 2022/1-30Swedish National Infrastructure for Computing (SNIC), SNIC 2022/22-106Swedish Research CouncilCarl Tryggers foundation , CTS 20-206EU, Horizon 2020, 865855
Available from: 2023-04-14 Created: 2023-04-14 Last updated: 2023-04-14Bibliographically approved
Pasti, I. A., Dobrota, A. S., Migas, D. B., Johansson, B. & Skorodumova, N. V. (2023). Theoretical analysis of electrochromism of Ni-deficient nickel oxide - from bulk to surfaces. Physical Chemistry, Chemical Physics - PCCP, 25(11), 7974-7985
Open this publication in new window or tab >>Theoretical analysis of electrochromism of Ni-deficient nickel oxide - from bulk to surfaces
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2023 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 25, no 11, p. 7974-7985Article in journal (Refereed) Published
Abstract [en]

The development of new electrochromic materials and devices, like smart windows, has an enormous impact on the energy efficiency of modern society. One of the crucial materials in this technology is nickel oxide. Ni-deficient NiO shows anodic electrochromism, whose mechanism is still under debate. We use DFT+U calculations to show that Ni vacancy generation results in the formation of hole polarons localized at the two oxygens next to the vacancy. In the case of NiO bulk, upon Li insertion or injection of an extra electron into Ni-deficient NiO, one hole gets filled, and the hole bipolaron is converted into a hole polaron well-localized at one O atom, resulting from the transition between oxidized (colored) to reduced (bleached) state. In the case of the Ni-deficient NiO(001) surface, the qualitatively same picture is obtained upon embedding Li, Na, and K into the Ni surface vacancy, reinforcing the conclusion that the electron injection, resulting in the filling of the hole states, is responsible for the modulation of the optical properties of NiO. Hence, our results suggest a new mechanism of Ni-deficient NiO electrochromism not related to the change of the Ni oxidation states, i.e., the Ni2+/Ni3+ transition, but based on the formation and annihilation of hole polarons in oxygen p-states.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2023
National Category
Condensed Matter Physics Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-499304 (URN)10.1039/d2cp05467a (DOI)000942904300001 ()36866780 (PubMedID)
Funder
Swedish Research Council, 2018-05973
Available from: 2023-03-30 Created: 2023-03-30 Last updated: 2023-03-30Bibliographically approved
Dobrota, A. S., Pasti, I. A., Mentus, S. V., Johansson, B. & Skorodumova, N. V. (2020). Altering the reactivity of pristine, N- and P-doped graphene by strain engineering: A DFT view on energy related aspects. Applied Surface Science, 514, Article ID 145937.
Open this publication in new window or tab >>Altering the reactivity of pristine, N- and P-doped graphene by strain engineering: A DFT view on energy related aspects
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2020 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 514, article id 145937Article in journal (Refereed) Published
Abstract [en]

For carbon-based materials, in contrast to metal surfaces, a general relationship between strain and reactivity is not yet established, even though there are literature reports on strained graphene. Knowledge of such relationships would be extremely beneficial for understanding the reactivity of graphene-based surfaces and finding optimisation strategies which would make these materials more suitable for targeted applications. Here we investigate the effects of compressive and tensile strain (up to +/- 5%) on the structure, electronic properties and reactivity of pure, N-doped and P-doped graphene, using DFT calculations. We demonstrate the possibility of tuning the topology of the graphene surface by strain, as well as by the choice of the dopant atom. The reactivity of (doped) strained graphene is probed using H and Na as simple adsorbates of great practical importance. Strain can both enhance and weaken H and Na adsorption on (doped) graphene. In case of Na adsorption, a linear relationship is observed between the Na adsorption energy on P-doped graphene and the phosphorus charge. A linear relationship between the Na adsorption energy on flat graphene surfaces and strain is found. Based on the adsorption energies and electrical conductivity, potentially good candidates for hydrogen storage and sodiumion battery electrodes are discussed.

Keywords
Graphene, Doped graphene, Strain, Curvature, Reactivity
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-409701 (URN)10.1016/j.apsusc.2020.145937 (DOI)000523185200006 ()
Funder
Swedish Research Council, 2014-5993Carl Tryggers foundation
Available from: 2020-05-05 Created: 2020-05-05 Last updated: 2020-05-05Bibliographically approved
Novcic, K. A., Dobrota, A. S., Petkovic, M., Johansson, B., Skorodumova, N. V., Mentus, S. V. & Pasti, I. A. (2020). Theoretical analysis of doped graphene as cathode catalyst in Li-O2 and Na-O2 batteries: the impact of the computational scheme. Electrochimica Acta, 354, Article ID 136735.
Open this publication in new window or tab >>Theoretical analysis of doped graphene as cathode catalyst in Li-O2 and Na-O2 batteries: the impact of the computational scheme
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2020 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 354, article id 136735Article in journal (Refereed) Published
Abstract [en]

Understanding the reactions in M-O-2 cells (M = Li or Na) is of great importance for further advancement of this promising technology. Computational modelling can be helpful along this way, but an adequate approach is needed to model such complex systems. We propose a new scheme for modelling processes in M-O-2 cells, where reference energies are obtained from high-level theory, CCSD(T), while the interactions of reaction intermediates with catalyst surfaces are extracted from computationally less expensive DFT. The approach is demonstrated for the case of graphene-based surfaces as model catalysts in Li-O-2 and Na-O-2 cells using the minimum viable mechanism. B-doped graphene was identified as the best catalyst amongst considered surfaces, while pristine graphene performs poorly. Moreover, we show that the inclusion of dispersion corrections for DFT has a significant impact on calculated discharge and charge potentials and suggests that long-range dispersion interactions should always be considered when graphene-based materials are modelled as electrocatalysts. Finally, we offer general guidelines for designing new ORR catalysts for M-O-2 cells in terms of the optimization of the interactions of catalyst surface with reaction intermediates.

Place, publisher, year, edition, pages
Elsevier BV, 2020
Keywords
Graphene, Doped graphene, Metal-air batteries, Oxygen reduction reaction, Modelling
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:uu:diva-423076 (URN)10.1016/j.electacta.2020.136735 (DOI)000569141000014 ()
Funder
Swedish Research Council, 2014-5993Carl Tryggers foundation , 18:177
Available from: 2020-10-21 Created: 2020-10-21 Last updated: 2020-10-21Bibliographically approved
Tao, Q., Lu, J., Dahlqvist, M., Mockute, A., Calder, S., Petruhins, A., . . . Rosen, J. (2019). Atomically Layered and Ordered Rare-Earth i-MAX Phases: A New Class of Magnetic Quaternary Compounds. Chemistry of Materials, 31(7), 2476-2485
Open this publication in new window or tab >>Atomically Layered and Ordered Rare-Earth i-MAX Phases: A New Class of Magnetic Quaternary Compounds
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2019 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 31, no 7, p. 2476-2485Article in journal (Refereed) Published
Abstract [en]

In 2017, we discovered quaternary i-MAX phases atomically layered solids, where M is an early transition metal, A is an A group element, and X is C—with a (M12/3M21/3)2AC chemistry, where the M1 and M2 atoms are in-plane ordered. Herein, we report the discovery of a class of magnetic i-MAX phases in which bilayers of a quasi-2D magnetic frustrated triangular lattice overlay a Mo honeycomb arrangement and an Al Kagome lattice. The chemistry of this family is (Mo2/3RE1/3)2AlC, and the rare-earth, RE, elements are Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu. The magnetic properties were characterized and found to display a plethora of ground states, resulting from an interplay of competing magnetic interactions in the presence of magnetocrystalline anisotropy.

National Category
Condensed Matter Physics Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-382860 (URN)10.1021/acs.chemmater.8b05298 (DOI)000464477100029 ()
Funder
Knut and Alice Wallenberg Foundation, KAW 2015.0043Swedish Research Council, 642-2013-8020Swedish Research Council, 2015-00607Swedish Research Council, 621-2014-4890Swedish National Infrastructure for Computing (SNIC)German Research Foundation (DFG), SA 3095/2-1
Available from: 2019-05-10 Created: 2019-05-10 Last updated: 2019-05-10Bibliographically approved
Al-Zoubi, N., Schonecker, S., Li, X., Li, W., Johansson, B. & Vitos, L. (2019). Elastic properties of 4d transition metal alloys: Values and trends. Computational materials science, 159, 273-280
Open this publication in new window or tab >>Elastic properties of 4d transition metal alloys: Values and trends
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2019 (English)In: Computational materials science, ISSN 0927-0256, E-ISSN 1879-0801, Vol. 159, p. 273-280Article in journal (Refereed) Published
Abstract [en]

Using the Exact Muffin-Tin Orbitals method within the Perdew-Burke-Ernzerhof exchange-correlation approximation for solids and solid surfaces (PBEso1), we study the single crystal elastic constants of 4d transition metals (atomic number Z between 39 and 47) and their binary alloys in the body centered cubic (bcc) and face centered cubic (fcc) structures. Alloys between the first neighbors Z(Z + 1) and between the second neighbors Z(Z + 2) are considered. The lattice constants, bulk moduli and elastic constants are found in good agreement with the available experimental and theoretical data. It is shown that the correlation between the relative tetragonal shear elastic constant C-fcc'-2C(bcc)' and the structural energy difference between the fcc and bcc lattices Delta E is superior to the previously considered models. For a given crystal structure, the equiatomic Z(Z + 2) alloys turn out to have similar structural and elastic properties as the pure elements with atomic number (Z + 1). Furthermore, alloys with composition Z(1-x)(Z + 2)(x) possess similar properties as Z(1-2x)(Z + 1)(2x). The present theoretical data on the structural and the elastic properties of 4d transition metal alloys provides consistent input for coarse scale modeling of material properties.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2019
Keywords
Exact muffin-tin orbital method, 4d transition metals, Binary alloys, Elastic constants, First-principles, Structural properties
National Category
Condensed Matter Physics Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:uu:diva-378523 (URN)10.1016/j.commatsci.2018.12.027 (DOI)000457856900027 ()
Funder
Swedish Research CouncilSwedish Foundation for Strategic Research The Swedish Foundation for International Cooperation in Research and Higher Education (STINT)Carl Tryggers foundation
Available from: 2019-03-25 Created: 2019-03-25 Last updated: 2019-03-25Bibliographically approved
Li, X., Schonecker, S., Li, X., Hao, S., Zhao, J., Johansson, B. & Vitos, L. (2019). First-principles study of crystal-face specificity in surface properties of Fe-rich Fe-Cr alloys. Physical Review Materials, 3(3), Article ID 034401.
Open this publication in new window or tab >>First-principles study of crystal-face specificity in surface properties of Fe-rich Fe-Cr alloys
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2019 (English)In: Physical Review Materials, E-ISSN 2475-9953, Vol. 3, no 3, article id 034401Article in journal (Refereed) Published
Abstract [en]

A density-functional theory investigation of the (100) and (110) surfaces of the body-centered cubic (bcc) Fe1-xbCrxb binary alloys, x(b) <= 15 at.%, is reported. The energies and segregation energies of these surfaces were calculated for chemically homogeneous concentration profiles and for Cr surface contents deviating from the nominal one of the bulk. The implications of these results for the surface alloy phase diagram are discussed. The surface chemistry of Fe-Cr(100) is characterized by a transition from Cr depletion to Cr enrichment in a critical bulk Cr composition window of 6 < x(b) < 9 at.%. In contrast, such threshold behavior of the surface Cr content is absent for Fe-Cr(110) and a nearly homogeneous Cr concentration profile is energetically favorable. The strongly suppressed surface-layer relaxation at both surfaces is shown to be of magnetic origin. The compressive, magnetic contribution to the surface relaxation stress is found to correlate well with the surface magnetic moment squared at both surface terminations. The stability of the Cr surface magnetic moments against bulk Cr content is clarified based on the surface electronic structure.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-379928 (URN)10.1103/PhysRevMaterials.3.034401 (DOI)000460683400001 ()
Funder
Swedish Research CouncilSwedish Foundation for Strategic Research
Available from: 2019-03-28 Created: 2019-03-28 Last updated: 2020-12-15Bibliographically approved
Diklic, N. P., Dobrota, A. S., Pasti, I. A., Mentus, S. V., Johansson, B. & Skorodumova, N. V. (2019). Sodium storage via single epoxy group on graphene: The role of surface doping. Electrochimica Acta, 297, 523-528
Open this publication in new window or tab >>Sodium storage via single epoxy group on graphene: The role of surface doping
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2019 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 297, p. 523-528Article in journal (Refereed) Published
Abstract [en]

Due to its unique physical and chemical properties, graphene is being considered as a promising material for energy conversion and storage applications. Introduction of functional groups and dopants on/in graphene is a useful strategy for tuning its properties. In order to fully exploit its potential, atomic-level understanding of its interaction with species of importance for such applications is required. We present a DFT study of the interaction of sodium atoms with epoxy-graphene and analyze how this interaction is affected upon doping with boron and nitrogen. We demonstrate how the dopants, combined with oxygen-containing groups alter the reactivity of graphene towards Na. Dopants act as attractors of epoxy groups, enhancing the sodium adsorption on doped oxygen-functionalized graphene when compared to the case of non-doped epoxy-graphene. Furthermore, by considering thermodynamics of the Na interaction with doped epoxy-graphene it has been concluded that such materials are good candidates for Na storage applications. Therefore, we suggest that controlled oxidation of doped carbon materials could lead to the development of advanced anode materials for rechargeable Na-ion batteries.

Keywords
Graphene, Graphene doping, Graphene oxidation, Sodium storage, Battery
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-375795 (URN)10.1016/j.electacta.2018.11.108 (DOI)000455642500058 ()
Funder
Swedish Research Council, 2014-5993Carl Tryggers foundation , 17:503Swedish National Infrastructure for Computing (SNIC)
Available from: 2019-02-15 Created: 2019-02-15 Last updated: 2019-02-15Bibliographically approved
Pasti, I. A., Jovanovic, A., Dobrota, A. S., Mentus, S. V., Johansson, B. & Skorodumova, N. V. (2018). Atomic adsorption on graphene with a single vacancy: systematic DFT study through the periodic table of elements. Physical Chemistry, Chemical Physics - PCCP, 20(2), 858-865
Open this publication in new window or tab >>Atomic adsorption on graphene with a single vacancy: systematic DFT study through the periodic table of elements
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2018 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 2, p. 858-865Article in journal (Refereed) Published
Abstract [en]

Vacancies in graphene present sites of altered chemical reactivity and open possibilities to tune graphene properties by defect engineering. The understanding of chemical reactivity of such defects is essential for successful implementation of carbon materials in advanced technologies. We report the results of a systematic DFT study of atomic adsorption on graphene with a single vacancy for the elements of rows 1-6 of the periodic table of elements (PTE), excluding lanthanides. The calculations have been performed using the PBE, long-range dispersion interaction-corrected PBE (PBE+D2 and PBE+D3) and non-local vdW-DF2 functionals. We find that most elements strongly bind to the vacancy, except for the elements of groups 11 and 12, and noble gases, for which the contribution of dispersion interaction to bonding is most significant. The strength of the interaction with the vacancy correlates with the cohesive energy of the elements in their stable phases: the higher the cohesive energy is, the stronger bonding to the vacancy can be expected. As most atoms can be trapped at the SV site we have calculated the potentials of dissolution and found that in most cases the metals adsorbed at the vacancy are more "noble" than they are in their corresponding stable phases.

National Category
Chemical Sciences Physical Sciences
Identifiers
urn:nbn:se:uu:diva-341487 (URN)10.1039/c7cp07542a (DOI)000419219700015 ()29238768 (PubMedID)
Available from: 2018-02-28 Created: 2018-02-28 Last updated: 2018-02-28Bibliographically approved
Pasti, I. A., Jovanovic, A., Dobrota, A. S., Mentus, S. V., Johansson, B. & Skorodumova, N. V. (2018). Atomic adsorption on pristine graphene along the Periodic Table of Elements - From PBE to non-local functionals. Applied Surface Science, 436, 433-440
Open this publication in new window or tab >>Atomic adsorption on pristine graphene along the Periodic Table of Elements - From PBE to non-local functionals
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2018 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 436, p. 433-440Article in journal (Refereed) Published
Abstract [en]

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

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
Keywords
Graphene, Adsorption, Atomic adsorption, Periodic Table of Elements, Dispersion interactions
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-350485 (URN)10.1016/j.apsusc.2017.12.046 (DOI)000425723100050 ()
Funder
Swedish Research Council, 348-2012-6196]Swedish Research Council, 2014-5993]Carl Tryggers foundation
Available from: 2018-05-17 Created: 2018-05-17 Last updated: 2018-05-17Bibliographically approved
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