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Butorin, Sergei
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Publications (10 of 57) Show all publications
Kvashnina, K. O., Romanchuk, A. Y., Pidchenko, I., Amidani, L., Gerber, E., Trigub, A., . . . Kalmykov, S. N. (2019). A Novel Metastable Pentavalent Plutonium Solid Phase on the Pathway from Aqueous Plutonium(VI) to PuO2 Nanoparticles. Angewandte Chemie International Edition
Open this publication in new window or tab >>A Novel Metastable Pentavalent Plutonium Solid Phase on the Pathway from Aqueous Plutonium(VI) to PuO2 Nanoparticles
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2019 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773Article in journal (Refereed) Published
Abstract [en]

Here we provide evidence that the formation of PuO2 nanoparticles from oxidized PuVI under alkaline conditions proceeds through the formation of an intermediate PuV solid phase, similar to NH4PuO2CO3, which is stable over a period of several months. For the first time, state‐of‐the‐art experiments at Pu M4 and at L3 absorption edges combined with theoretical calculations unambiguously allow to determine the oxidation state and the local structure of this intermediate phase.

Keywords
actinide chemistry, electronic-structure calculations, pentavalent plutonium, plutonium dioxide nanoparticles, Pu M-4 HERFD
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-397631 (URN)10.1002/anie.201911637 (DOI)000494496600001 ()31621992 (PubMedID)
Funder
EU, European Research Council, N759696Swedish Research Council, 2017-06465
Note

Early View: Online Version of Record before inclusion in an issue

Available from: 2019-11-22 Created: 2019-11-22 Last updated: 2019-11-22Bibliographically approved
Phuyal, D., Mukherjee, S., Jana, S., Denoel, F., Kamalakar, M. V., Butorin, S. M., . . . Karis, O. (2019). Ferroelectric properties of BaTiO3 thin films co-doped with Mn and Nb. AIP Advances, 9(9), Article ID 095207.
Open this publication in new window or tab >>Ferroelectric properties of BaTiO3 thin films co-doped with Mn and Nb
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2019 (English)In: AIP Advances, ISSN 2158-3226, E-ISSN 2158-3226, Vol. 9, no 9, article id 095207Article in journal (Refereed) Published
Abstract [en]

We report on properties of BaTiO3 thin films where the bandgap is tuned via aliovalent doping of Mn and Nb ions co-doped at the Ti site. The doped films show single-phase tetragonal structure, growing epitaxially with a smooth interface to the substrate. Using piezoforce microscopy, we find that both doped and undoped films exhibit good ferroelectric response. The piezoelectric domain switching in the films was confirmed by measuring local hysteresis of the polarization at several different areas across the thin films, demonstrating a switchable ferroelectric state. The doping of the BaTiO3 also reduces the bandgap of the material from 3.2 eV for BaTiO3 to nearly 2.7 eV for the 7.5% doped sample, suggesting the viability of the films for effective light harvesting in the visible spectrum. The results demonstrate co-doping as an effective strategy for bandgap engineering and a guide for the realization of visible-light applications using its ferroelectric properties.

Place, publisher, year, edition, pages
American Institute of Physics, 2019
Keywords
ferroelectric, complex oxides
National Category
Condensed Matter Physics
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-393045 (URN)10.1063/1.5118869 (DOI)000488516200011 ()
Funder
Swedish Research Council, 2018-04330Swedish Research Council, 2016-4524Knut and Alice Wallenberg Foundation, 2012.0031Carl Tryggers foundation , CTS-17:376Swedish Energy Agency, P43549-1
Available from: 2019-09-13 Created: 2019-09-13 Last updated: 2019-11-06Bibliographically approved
Plakhova, T. V., Romanchuk, A. Y., Butorin, S., Konyukhova, A. D., Egorov, A. V., Shiryaev, A. A., . . . Kvashnina, K. O. (2019). Towards the surface hydroxyl species in CeO2 nanoparticles. Nanoscale, 11(39), 18142-18149
Open this publication in new window or tab >>Towards the surface hydroxyl species in CeO2 nanoparticles
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2019 (English)In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 11, no 39, p. 18142-18149Article in journal (Refereed) Published
Abstract [en]

Understanding the complex chemistry of functional nanomaterials is of fundamental importance. Controlled synthesis and characterization at the atomic level is essential to gain deeper insight into the unique chemical reactivity exhibited by many nanomaterials. Cerium oxide nanoparticles have many industrial and commercial applications, resulting from very strong catalytic, pro- and anti-oxidant activity. However, the identity of the active species and the chemical mechanisms imparted by nanoceria remain elusive, impeding the further development of new applications. Here, we explore the behavior of cerium oxide nanoparticles of different sizes at different temperatures and trace the electronic structure changes by state-of-the-art soft and hard X-ray experiments combined with computational methods. We confirm the absence of the Ce(III) oxidation state at the surface of CeO2 nanoparticles, even for particles as small as 2 nm. Synchrotron X-ray absorption experiments at Ce L-3 and M-5 edges, combined with X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and small angle X-ray scattering (SAXS) and theoretical calculations demonstrate that in addition to the nanoceria charge stability, the formation of hydroxyl groups at the surface profoundly affects the chemical performance of these nanomaterials.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-406904 (URN)10.1039/c9nr06032d (DOI)000512634500021 ()31555787 (PubMedID)
Funder
EU, European Research Council, 759696Swedish Research Council, 2017-06465
Available from: 2020-03-20 Created: 2020-03-20 Last updated: 2020-03-20Bibliographically approved
Amidani, L., Plakhova, T. V., Romanchuk, A. Y., Gerber, E., Weiss, S., Efimenko, A., . . . Kvashnina, K. O. (2019). Understanding the size effects on the electronic structure of ThO2 nanoparticles. Physical Chemistry, Chemical Physics - PCCP, 21(20), 10635-10643
Open this publication in new window or tab >>Understanding the size effects on the electronic structure of ThO2 nanoparticles
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2019 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 21, no 20, p. 10635-10643Article in journal (Refereed) Published
Abstract [en]

Developing characterization techniques and analysis methods adapted to the investigation of nanoparticles (NPs) is of fundamental importance considering the role of these materials in many fields of research. The study of actinide based NPs, despite their environmental relevance, is still underdeveloped compared to that of NPs based on stable and lighter elements. We present here an investigation of ThO2 NPs performed with High-Energy Resolution Fluorescence Detected (HERFD) X-ray Absorption Near-Edge Structure (XANES) and with ab initio XANES simulations. The first post-edge feature of Th L-3 edge HERFD XANES disappears in small NPs and simulations considering non-relaxed structural models reproduce the trends observed in experimental data. Inspection of the simulations of Th atoms in the core and on the surface of the NP indeed demonstrates that the first post-edge feature is very sensitive to the lowering of the number of coordinating atoms and therefore to the more exposed Th atoms at the surface of the NP. The sensitivity of the L-3 edge HERFD XANES to low coordinated atoms at the surface stems from the hybridization of the d-Density of States (DOS) of Th with both O and Th neighboring atoms. This may be a common feature to other oxide systems that can be exploited to investigate surface interactions.

National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-392061 (URN)10.1039/c9cp01283d (DOI)000476561000039 ()31080986 (PubMedID)
Funder
EU, European Research Council, 759696Swedish Research Council, 2017-06465
Available from: 2019-09-10 Created: 2019-09-10 Last updated: 2019-09-10Bibliographically approved
Butorin, S., Kvashnina, K. O., Klintenberg, M., Kavcic, M., Zitnik, M., Bucar, K., . . . Lenoir, B. (2018). Effect of Ag Doping on Electronic Structure of Cluster Compounds AgxMo9Se11 (x = 3.4, 3.9). ACS APPLIED ENERGY MATERIALS, 1(8), 4032-4039
Open this publication in new window or tab >>Effect of Ag Doping on Electronic Structure of Cluster Compounds AgxMo9Se11 (x = 3.4, 3.9)
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2018 (English)In: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 1, no 8, p. 4032-4039Article in journal (Refereed) Published
Abstract [en]

The electronic structure of AgxMo9Se11 as a potential material for thermoelectric applications was studied using high-energy-resolution fluorescence-detection X-ray absorption spectroscopy (HERFD-XAS) and the resonant inelastic X-ray scattering (RIXS) technique. The experiments were supported by first-principle calculations using density functional theory (DFT). The analysis of obtained spectra indicate the presence of subvalent (less than 1+) Ag in AgxMo9Se11. The advanced HERFD-XAS measurements allowed us to resolve the contribution of the electronic states at the Fermi level of AgxMo9Se11 and to monitor its dependence on the x value. A comparison of the experimental data with the results of the DFT calculations suggests the importance of the Ag2-type sites with the shortest Ag–Se distance for affecting the properties of AgxMo9Se11.

Keywords
thermoelectric applications, X-ray spectroscopy, density functional theory
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:uu:diva-378748 (URN)10.1021/acsaem.8b00718 (DOI)000458706400060 ()
Available from: 2019-03-11 Created: 2019-03-11 Last updated: 2019-03-11Bibliographically approved
Phuyal, D., Safdari, M., Pazoki, M., Liu, P., Philippe, B., Kvashnina, K. O., . . . Gardner, J. (2018). Electronic Structure of Two-Dimensional Lead(II) Iodide Perovskites: An Experimental and Theoretical Study. Chemistry of Materials, 30(15), 4959-4967
Open this publication in new window or tab >>Electronic Structure of Two-Dimensional Lead(II) Iodide Perovskites: An Experimental and Theoretical Study
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2018 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 30, no 15, p. 4959-4967Article in journal (Refereed) Published
Abstract [en]

Layered two-dimensional (2D) hybrid organic-inorganic perovskites (HOP) are promising materials for light-harvesting applications because of their chemical stability, wide flexibility in composition and dimensionality, and increases in photovoltaic power conversion efficiencies. Three 2D lead iodide perovskites were studied through various X-ray spectroscopic techniques to derive detailed electronic structures and band energetics profiles at a titania interface. Core-level and valence band photoelectron spectra of HOP were analyzed to resolve the electronic structure changes due to the reduced dimensionality of inorganic layers. The results show orbital narrowing when comparing the HOP, the layered precursor PbI2, and the conventional 3D (CH3NH3)PbI3 such that different localizations of band edge states and narrow band states are unambiguously due to the decrease in dimensionality of the layered HOPs. Support from density functional theory calculations provide further details on the interaction and band gap variations of the electronic structure. We observed an interlayer distance dependent dispersion in the near band edge electronic states. The results show how tuning the interlayer distance between the inorganic layers affects the electronic properties and provides important design principles for control of the interlayer charge transport properties, such as the change in effective charge masses as a function of the organic cation length. The results of these findings can be used to tune layered materials for optimal functionality and new applications.

National Category
Condensed Matter Physics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-361922 (URN)10.1021/acs.chemmater.8b00909 (DOI)000442186500014 ()
Funder
StandUpSwedish Energy AgencySwedish Research CouncilKnut and Alice Wallenberg Foundation
Note

De två första författarna delar förstaförfattarskapet.

Available from: 2018-09-27 Created: 2018-09-27 Last updated: 2018-11-02Bibliographically approved
Bes, R., Kvashnina, K., Rossberg, A., Dottavio, G., Desgranges, L., Pontillon, Y., . . . Martin, P. (2018). New insight in the uranium valence state determination in UyNd1-yO2 +/- x. Journal of Nuclear Materials, 507, 145-150
Open this publication in new window or tab >>New insight in the uranium valence state determination in UyNd1-yO2 +/- x
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2018 (English)In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 507, p. 145-150Article in journal (Refereed) Published
Abstract [en]

The charge compensation mechanisms in UyNd1-yO2 +/- x, and its consequence on the overall O stoichiometry (or O/M ratio where M = Nd + U) have been studied through the uranium valence state mixture evolution as a function of Nd content up to y = 0.62 by means of high energy resolution fluorescence detection X-ray absorption spectroscopy (HERFD-XAS) at the U M-4-edge. Our results clearly demonstrate the formation of U5+ at low Nd content (y < 0.15). Upon increasing the Nd content, oxygen vacancies and the formation of U6+ appear as competing mechanisms for intermediate Nd concentrations, leading to the co-existence of U4+/U5+/U6+ mixed valence and an overall hypostoichiometry (O/M < 2.00). Finally, the formation of U6+ associated with strongly distorted U local environment is observed for high Nd concentrations (y = 0.62), leading to an overall hyperstoichiometry (O/M < 2.00).

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2018
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-361029 (URN)10.1016/j.jnucmat.2018.04.046 (DOI)000438019800017 ()
Funder
Swedish Research Council, 2017-06465
Available from: 2018-09-20 Created: 2018-09-20 Last updated: 2018-09-20Bibliographically approved
Phuyal, D., Jain, S. M., Philippe, B., Johansson, M. B., Pazoki, M., Kullgren, J., . . . Rensmo, H. (2018). The electronic structure and band interface of cesium bismuth iodide on a titania heterostructure using hard X-ray spectroscopy. Journal of Materials Chemistry A, 6(20), 9498-9505
Open this publication in new window or tab >>The electronic structure and band interface of cesium bismuth iodide on a titania heterostructure using hard X-ray spectroscopy
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2018 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, no 20, p. 9498-9505Article in journal (Refereed) Published
Abstract [en]

Bismuth halide compounds as a non-toxic alternative are increasingly investigated because of their potential in optoelectronic devices and their rich structural chemistry. Hard X-ray spectroscopy was applied to the ternary bismuth halide Cs3Bi2I9 and its related precursors BiI3 and CsI to understand its electronic structure at an atomic level. We specifically investigated the core levels and valence band using X-ray photoemission spectroscopy (PES), high-resolution X-ray absorption (HERFD-XAS), and resonant inelastic X-ray scattering (RIXS) to get insight into the chemistry and the band edge properties of the two bismuth compounds. Using these element specific X-ray techniques, our experimental electronic structures show that the primary differences between the two bismuth samples are the position of the iodine states in the valence and conduction bands and the degree of hybridization with bismuth lone pair (6s(2)) states. The crystal structure of the two layered quasi-perovskite compounds plays a minor role in modifying the overall electronic structure, with variations in bismuth lone pair states and iodine band edge states. Density Functional Theory (DFT) calculations are used to compare with experimental data. The results demonstrate the effectiveness of hard X-ray spectroscopies to identify element specific bulk electronic structures and their use in optoelectronic devices.

National Category
Materials Chemistry Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-357561 (URN)10.1039/c8ta00947c (DOI)000433427300020 ()
Funder
Swedish Research Council, 2014-6019Swedish Research Council, 2016-4524Swedish Energy Agency, P43549-1Swedish Foundation for Strategic Research , 15-0130Wallenberg Foundations, 2012.0031StandUp
Available from: 2018-08-20 Created: 2018-08-20 Last updated: 2019-02-19Bibliographically approved
Phuyal, D., Mukherjee, S., Das, S., Jana, S., Kvashnina, K. O., Sarma, D., . . . Karis, O. (2018). The origin of low bandgap and ferroelectricity of a co-doped BaTiO3. Europhysics letters, 124(2), Article ID 27005.
Open this publication in new window or tab >>The origin of low bandgap and ferroelectricity of a co-doped BaTiO3
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2018 (English)In: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 124, no 2, article id 27005Article in journal (Refereed) Published
Abstract [en]

We recently demonstrated the lowest bandgap bulk ferroelectric material, BaTi1-x(Mn1/2Nb1/2)xO3, a promising candidate material for visible light absorption in opto- electronic devices. Using a combination of x-ray spectroscopies and density functional theory (DFT) calculations, we here elucidate this compound’s electronic structure and the modifications induced by Mn doping. In particular, we are able to rationalize how this compound retains its ferroelectricity even through a significant reduction of the optical gap upon Mn doping. The local electronic structure and atomic coordination are investigated using x-ray absorption at the Ti K, Mn K, and O K edges, which suggests only small distortions to the parent tetragonal ferroelectric system, BaTiO3, thereby providing a clue to the substantial retention of ferroelectricity in spite of doping. Features at the Ti K edge, which are sensitive to local symmetry and an indication of Ti off-centering within the Ti-O6 octahedra, show modest changes with doping and strongly corroborates with our measured polarization values. Resonant photoelectron spectroscopy results suggest the origin of the reduction of the bandgap in terms of newly created Mn d bands that hybridize with O 2p states. X-ray absorption spectra at the O K-edge provide evidence for new states below the conduction band of the parent compound, illustrating additional contributions facilitating bandgap reduction.

National Category
Condensed Matter Physics
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-364369 (URN)10.1209/0295-5075/124/27005 (DOI)000450630500002 ()
Funder
Swedish Foundation for Strategic Research , 15-0130Knut and Alice Wallenberg Foundation, 2012.0031Swedish Energy Agency, P43549-1Swedish Energy Agency, P43294-1Swedish Research Council, 2014-7019Swedish Research Council, 2016-4524
Note

Corection in: EPL, Volume: 124, Issue: 6, Article Number: 69901, DOI: 10.1209/0295-5075/124/69901

Available from: 2018-10-25 Created: 2018-10-25 Last updated: 2019-02-04Bibliographically approved
Kvashnina, K. O., Kowalski, P. M., Butorin, S., Leinders, G., Pakarinen, J., Bes, R., . . . Verwerft, M. (2018). Trends in the valence band electronic structures of mixed uranium oxides. Chemical Communications, 54(70), 9757-9760
Open this publication in new window or tab >>Trends in the valence band electronic structures of mixed uranium oxides
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2018 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 54, no 70, p. 9757-9760Article in journal (Refereed) Published
Abstract [en]

The valence band electronic structures of mixed uranium oxides (UO2 , U4O9 , U3O7, U3O8 , and beta-UO3) have been studied using the resonant inelastic X-ray scattering (RIXS) technique at the U M-5 edge and computational methods. We show here that the RIXS technique and recorded U 5f-O 2p charge transfer excitations can be used to test the validity of theoretical approximations.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2018
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-362100 (URN)10.1039/c8cc05464a (DOI)000442872000010 ()30109321 (PubMedID)
Available from: 2018-10-01 Created: 2018-10-01 Last updated: 2018-10-01Bibliographically approved
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