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Author Volykhov, A.A.; Frolov, A.S.; Neudachina, V.S.; Vladimirova, N.V.; Gerber, E.; Callaert, C.; Hadermann, J.; Khmelevsky, N.O.; Knop-Gericke, A.; Sanchez-Barriga, J.; Yashina, L.V.
Title Impact of ordering on the reactivity of mixed crystals of topological insulators with anion substitution: Bi₂SeTe₂ and Sb₂SeTe₂ Type A1 Journal article
Year 2021 Publication Applied Surface Science Abbreviated Journal Appl Surf Sci
Volume (up) 541 Issue Pages 148490
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Three-dimensional topological insulators are exotic materials with unique properties. Tetradymite type binary chalcogenides of bismuth and antimony, as well as their mixed crystals, belong to prototypical TIs. Potential device applications of these materials require in-depth knowledge of their stability in the ambient atmosphere and other media maintained during their processing. Here we investigated the reactivity of mixed crystals with anion substitution, Bi-2(Se1-xTex)(3) and Sb2(Se1-xTex)(3), towards molecular oxygen using both in situ and ex situ X-ray photoelectron spectroscopy. The results indicate that, in contrast to cation substitution, partial substitution of tellurium by selenium atoms leads to anomalously high surface reactivity, which even exceeds that of the most reactive binary constituent. We attribute this effect to anion ordering that essentially modifies the bond geometry, especially the respective bond angles as modeled by DFT.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000608492900003 Publication Date 2020-11-18
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0169-4332 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.387 Times cited Open Access Not_Open_Access
Notes Approved Most recent IF: 3.387
Call Number UA @ admin @ c:irua:176067 Serial 6728
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Author Batuk, M.; Buffiere, M.; Zaghi, A.E.; Lenaers, N.; Verbist, C.; Khelifi, S.; Vleugels, J.; Meuris, M.; Hadermann, J.
Title Effect of the burn-out step on the microstructure of the solution-processed Cu(In,Ga)Se2 solar cells Type A1 Journal article
Year 2015 Publication Thin solid films : an international journal on the science and technology of thin and thick films Abbreviated Journal Thin Solid Films
Volume (up) 583 Issue 583 Pages 142-150
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract For the development of the photovoltaic industry cheap methods for the synthesis of Cu(In,Ga)Se-2 (CIGSe) based solar cells are required. In this work, CIGSe thin films were obtained by a solution-based method using oxygen-bearing derivatives. With the aimof improving the morphology of the printed CIGSe layers, we investigated two different annealing conditions of the precursor layer, consisting of (1) a direct selenization step (reference process), and (2) a pre-treatment thermal step prior to the selenization. We showed that the use of an Air/H2S burn-out step prior to the selenization step increases the CIGSe grain size and reduces the carbon content. However, it leads to the reduction of the solar cell efficiency from 4.5% in the reference sample down to 0.5% in the annealed sample. Detailed transmission electron microscopy analysis, including high angle annular dark field scanning transmission electron microscopy and energy dispersive X-ray mapping, was applied to characterize the microstructure of the film and to determine the relationship between microstructure and the solar cell performance. We demonstrated that the relatively low efficiency of the reference solar cells is related not only to the nanosize of the CIGSe grains and presence of the pores in the CIGSe layer, but also to the high amount of secondary phases, namely, In/Ga oxide (or hydroxide) amorphous matter, residuals of organicmatter (carbon), and copper sulfide that is formed at the CIGSe/MoSe2 interface. The annealing in H2S during the burn-out step leads to the formation of the copper sulfide at all grain boundaries and surfaces in the CIGSe layer, which results in the noticeably efficiency drop. (C) 2015 Elsevier B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Lausanne Editor
Language Wos 000353812400024 Publication Date 2015-04-05
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0040-6090; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.879 Times cited 5 Open Access
Notes Approved Most recent IF: 1.879; 2015 IF: 1.759
Call Number c:irua:126009 Serial 845
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Author Shpanchenko, R.V.; Chyornaya, V.V.; Abakumov, A.M.; Antipov, E.V.; Hadermann, J.; Van Tendeloo, G.; Kaul, E.; Geibel, C.; Sheptyakov, D.; Balagurov, A.M.
Title Crystal structure and magnetic properties of novel reduced V(IV)-based oxide Pb2V5O12 Type A1 Journal article
Year 2001 Publication Zeitschrift für anorganische und allgemeine Chemie Abbreviated Journal Z Anorg Allg Chem
Volume (up) 627 Issue Pages 2143-2150
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Leipzig Editor
Language Wos 000171339000023 Publication Date 2002-08-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0044-2313;1521-3749; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.144 Times cited 4 Open Access
Notes Approved Most recent IF: 1.144; 2001 IF: 1.165
Call Number UA @ lucian @ c:irua:36048 Serial 560
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Author Alekseeva, A.M.; Abakumov, A.M.; Leithe-Jasper, A.; Schnelle, W.; Prots, Y.; Hadermann, J.; Van Tendeloo, G.; Antipov, E.V.; Grin, Y.
Title Mg1-xRhB, a new boridometallide with 2D polyanion Type A1 Journal article
Year 2005 Publication Zeitschrift für anorganische und allgemeine Chemie Abbreviated Journal Z Anorg Allg Chem
Volume (up) 631 Issue 6/7 Pages 1047-1054
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Leipzig Editor
Language Wos 000228931900010 Publication Date 2005-04-18
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0044-2313;1521-3749; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.144 Times cited 13 Open Access
Notes Iap V-1 Approved Most recent IF: 1.144; 2005 IF: 1.202
Call Number UA @ lucian @ c:irua:52374 Serial 3543
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Author Deyneko, D.V.; Morozov, V.A.; Hadermann, J.; Savon, A.E.; Spassky, D.A.; Stefanovich, S.Y.; Belik, A.A.; Lazoryak, B.I.
Title A novel red Ca8.5Pb0.5Eu(PO4)7 phosphor for light emitting diodes application Type A1 Journal article
Year 2015 Publication Journal of alloys and compounds Abbreviated Journal J Alloy Compd
Volume (up) 647 Issue 647 Pages 965-972
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract Ca9-xPbxEu(PO4)(7) (0 <= x <= 1) solid solutions with a whitlockite-type (or beta-Ca-3(PO4)(2)-type) structure (sp.gr. R3c) were prepared by a standard solid-state method in air. Their luminescent properties under near-ultraviolet (n-UV) light were investigated. Excitation spectra of Ca9-xPbxEu(PO4)(7) showed the strongest absorption at about 395 nm, which matches well with commercially available n-UV-emitting GaN-based LED chips. Emission spectra indicated an intense red emission due to the D-5(0) -> F-7(2) transition of Eu3+, with a maximum in the intensity for Ca8.5Pb0.5Eu(PO4)(7). The emission intensity of Ca8.5Pb0.5Eu(PO4)(7) was about 1.8 times higher than that of a Ca9Eu(PO4)(7) phosphor. We suggest that the introduction of Pb2+ is an efficient approach to enhance luminescence properties of such phosphors. We clarified the influence of the Ca2+/Pb2+ substitution on intensities of three bands for the D-5(0) -> F-7(0) transition in excitation spectra of Ca9-xPbxEu(PO4)(7). In addition, we found a reversible first-order phase transition from R3c to R (3) over barc symmetry by second-harmonic generation in the range from 753 K (x = 1) to 846 K (x = 0). (C) 2015 Elsevier B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000361156400135 Publication Date 2015-06-18
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0925-8388 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.133 Times cited 18 Open Access
Notes Approved Most recent IF: 3.133; 2015 IF: 2.999
Call Number UA @ lucian @ c:irua:128720 Serial 4215
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Author Belik, A.A.; Morozov, V.A.; Deyneko, D.V.; Savon, A.E.; Baryshnikova, O.V.; Zhukovskaya, E.S.; Dorbakov, N.G.; Katsuya, Y.; Tanaka, M.; Stefanovich, S.Y.; Hadermann, J.; Lazoryak, B.I.
Title Antiferroelectric properties and site occupations ofR3+ cations in Ca8MgR(PO4)7 luminescent host materials Type A1 Journal article
Year 2017 Publication Journal of alloys and compounds Abbreviated Journal
Volume (up) 699 Issue Pages 928-937
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract Ca8MgR(PO4)(7) = La, Pr, Nd, Sm-Lu, and Y) phosphates with a beta-Ca-3(PO4)(2) related structure were prepared by a standard solid-state method in air. Second-harmonic generation, differential scanning calorimetry, and dielectric measurements led to the conclusion that all Ca8MgR(PO4)(7) are centrosymmetric and go to another centrosymmetric phase in the course of a first-order antiferroelectric phase transition well above room temperature (RT). High-temperature electron diffraction showed that the symmetry changes from R (3) over barc to R (3) over barm during the phase transition. Structures of Ca8MgR(PO4)(7) at RT were refined by the Rietveld method in centrosymmetric space group R (3) over barc. Mg2+ cations occupy the M5 site; the occupancy of the M1 site by R3+ cations increases monotonically from 0.0389 for R = La to 0.1667 for R = Er-Lu, whereas the occupancy of the M3 site by R3+ cations decreases monotonically from 0.1278 for R = La to 0 for R = Er-Lu. In the case of R = Er-Lu, the M3 site is occupied only by Ca2+ cations. P1O(4) tetrahedra and cations at the M3 site are disordered in the R (3) over barc structure of Ca8MgEu(PO4)(7). Using synchrotron X-ray powder diffraction, we found that annealing conditions do not significantly affect the distribution of Ca2+ and Eu3+ cations between the structure positions of Ca8MgEu(PO4)(7). Luminescent properties of CasMgEu(PO4)(7) powder samples were investigated under near-ultraviolet (n-UV) light. Excitation spectra of CasMgEu(PO4)(7) show the strongest absorption at about 395 nm that matches with commercially available n-UV-emitting GaN-based LED chips. Emission spectra show an intense red emission due to the D-5(0) -> F-7(2) transition of Eu3+. (C) 2016 Elsevier B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000393727500129 Publication Date 2016-12-24
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0925-8388 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited Open Access
Notes Approved no
Call Number UA @ admin @ c:irua:152665 Serial 7464
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Author Batuk, D.; Batuk, M.; Morozov, V.A.; Meert, K.W.; Smet, P.F.; Poelman, D.; Abakumov, A.M.; Hadermann, J.
Title Effect of cation vacancies on the crystal structure and luminescent properties of Ca(0.85-1.5x)Gd(x)Eu(0.1)_(0.05+0.5x)WO(4) (0<x<0.567) scheelite-based red phosphors Type A1 Journal article
Year 2017 Publication Journal of alloys and compounds Abbreviated Journal J Alloy Compd
Volume (up) 706 Issue 706 Pages 358-369
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract The Ca0.85-1.5xGdxEu0.1_0.05-0.5xWO4 (0 < x < 0.567) series of cation-deficient scheelites is investigated to unveil the influence of the cation vacancies on the crystal structure and luminescent properties. The concentration of the vacancies is varied by the heterovalent substitution of Gd3+ for Ca2+, keeping the concentration of the Eu3+ luminescent centers constant in all compounds of the series. The crystal structure of the materials is studied using a combination of transmission electron microscopy and synchrotron X-ray powder diffraction. At low vacancy concentration (x = 0.1, 0.2), cations and cation vacancies are randomly distributed in the structure, and the materials preserve the I41/a symmetry of the parent scheelite structure [x = 0.1: a = 5.25151(1) Å, c = 11.39479(2) Å; x = 0.2: a = 5.25042(1) Å, c = 11.41335(2) Å]. At higher concentration, the cation-vacancy ordering gives rise to incommensurately modulated structures. The x = 0.3 structure has a (3 + 2)D tetragonal symmetry [superspace group I41/a(a,b,0)00(-b,a,0)00, a = 5.24700(1) Å, c = 11.45514(3) Å, q1 = 0.51637(14)a* + 0.80761(13)b*, q2 = -0.80761a* + 0.51637b*]. At x = 0.4, the scheelite basic cell undergoes a monoclinic distortion with the formation of the (3 + 1)D structure [superspace group I2/b(a,b,0)00, a = 5.23757(1) Å, b = 5.25035(1) Å, c = 11.45750(2) Å, g = 90.5120(2) o, q = 0.54206(8)a* + 0.79330(8)b*]. In both structures, the antiphase Ca and (Gd,Eu) occupancy modulations indicate that the ordering between the A cations and vacancies also induces partial Ca/(Gd,Eu) cation ordering. Further increase of the Gd3þ content up to x = 0.567 leads to the formation of a monoclinic phase (space group C2/c) with the Eu2/3WO4-type structure. Despite the difference in the cation-vacancy ordering patterns, all materials in the series demonstrate very similar quantum efficiency and luminescence decay lifetimes. However, the difference in the local coordination environment of the A cation species noticeably affects the line width and the multiplet splitting of the 4f6-4f6 transitions.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000397997300045 Publication Date 2017-02-16
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0925-8388 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.133 Times cited 2 Open Access OpenAccess
Notes This research was supported by FWO (Flanders Research Foundation, project G039211N). V.A.M. is grateful for financial support of the Russian Foundation for Basic Research (Grant 15-03-07741).We are grateful to the ESRF for granting the beamtime at the ID22 beamline and to Andy Fitch for the support during the experiment. Approved Most recent IF: 3.133
Call Number EMAT @ emat @ c:irua:142367 Serial 4581
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Author Vladimirova, S.A.; Rumyantseva, M.N.; Filatova, D.G.; Chizhov, A.S.; Khmelevsky, N.O.; Konstantinova, E.A.; Kozlovsky, V.F.; Marchevsky, A.V.; Karakulina, O.M.; Hadermann, J.; Gaskov, A.M.
Title Cobalt location in p -CoO x / n -SnO 2 nanocomposites: Correlation with gas sensor performances Type A1 Journal Article
Year 2017 Publication Journal Of Alloys And Compounds Abbreviated Journal J Alloy Compd
Volume (up) 721 Issue Pages 249-260
Keywords A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Abstract Nanocomposites CoOx/SnO2 based on tin oxide powders with different crystallinity have been prepared by wet chemical synthesis and characterized in detail by ICP-MS, XPS, EPR, XRD, HAADF-STEM imaging and EDX-STEM mapping. It was shown that cobalt is distributed differently between the bulk and surface of SnO2 nanocrystals, which depends on the crystallinity of the SnO2 matrix. The measurements of gas sensor properties have been carried out during exposure to CO (10 ppm), and H2S (2 ppm) in dry air. The decrease of sensor signal toward CO was attributed to high catalytic activity of Co3O4 leading to oxidation of carbon monoxide entirely on the surface of catalyst particles. The formation of a p-CoOx/n-SnO2 heterojunction results in high sensitivity of nanocomposites in H2S detection. The conductance significantly changed in the presence of H2S, which was attributed to the formation of metallic cobalt sulfide and removal of the p – n junction.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000405252400030 Publication Date 2017-06-02
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0925-8388 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.133 Times cited Open Access Not_Open_Access
Notes This work was supported by ERA-Net.Plus grant N 096 FONSENS. EPR experiments were performed using the facilities of the Collective Use Center at the Moscow State University. Approved Most recent IF: 3.133
Call Number EMAT @ emat @ Serial 4711
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Author Vladimirova, S.A.; Rumyantseva, M.N.; Filatova, D.G.; Chizhov, A.S.; Khmelevsky, N.O.; Konstantinova, E.A.; Kozlovsky, V.F.; Marchevsky, A.V.; Karakulina, O.M.; Hadermann, J.; Gaskov, A.M.
Title Cobalt location in p-CoOxIn-SnO2 nanocomposites : correlation with gas sensor performances Type A1 Journal article
Year 2017 Publication Journal of alloys and compounds Abbreviated Journal J Alloy Compd
Volume (up) 721 Issue Pages 249-260
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract Nanocomposites CoOx/SnO2 based on tin oxide powders with different crystallinity have been prepared by wet chemical synthesis and characterized in detail by ICP-MS, XPS, EPR, XRD, HAADF-STEM imaging and EDX-STEM mapping. It was shown that cobalt is distributed differently between the bulk and surface of SnO2 nanocrystals, which depends on the crystallinity of the SnO2 matrix. The measurements of gas sensor properties have been carried out during exposure to CO (10 ppm), and H2S (2 ppm) in dry air. The decrease of sensor signal toward CO was attributed to high catalytic activity of Co3O4 leading to oxidation of carbon monoxide entirely on the surface of catalyst particles. The formation of a p-CoOx/n-SnO2 heterojunction results in high sensitivity of nanocomposites in H2S detection. The conductance significantly changed in the presence of H2S, which was attributed to the formation of metallic cobalt sulfide and removal of the p – n junction. (C) 2017 Elsevier B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos Publication Date
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0925-8388 ISBN Additional Links UA library record; ; WoS full record; WoS citing articles
Impact Factor 3.133 Times cited Open Access Not_Open_Access: Available from 10.10.2019
Notes ; This work was supported by ERA-Net.Plus grant N 096 FON-SENS. EPR experiments were performed using the facilities of the Collective Use Center at the Moscow State University. ; Approved Most recent IF: 3.133
Call Number UA @ lucian @ c:irua:145142 Serial 4714
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Author Ciocarlan, R.-G.; Seftel, E.M.; Gavrila, R.; Suchea, M.; Batuk, M.; Mertens, M.; Hadermann, J.; Cool, P.
Title Spinel nanoparticles on stick-like Freudenbergite nanocomposites as effective smart-removal photocatalysts for the degradation of organic pollutants under visible light Type A1 Journal article
Year 2020 Publication Journal Of Alloys And Compounds Abbreviated Journal J Alloy Compd
Volume (up) 820 Issue Pages 153403
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Abstract A series of mixed nanocomposite materials was synthetized, containing a Ferrite phase type Zn1-xNixFe2O4 and a Freudenbergite phase type Na2Fe2Ti6O16, where x = 0; 0.2; 0.4; 0.6; 0.8; 1. The choice for this combination is based on the good adsorption properties of Freudenbergite for dye molecules, and the small bandgap energy of Ferrite spinel, allowing activation of the catalysts under visible light irradiation. A two steps synthesis protocol was used to obtain the smart-removal nanocomposites. Firstly, the spinel structure was obtained via the co-precipitation route followed by the addition of the Ti-source and formation of the Freudenbergite system. The role of cations on the formation mechanism and an interesting interchange of cations between spinel and Freudenbergite structures was clarified by a TEM study. Part of the Ti4+ penetrated the spinel structure and, at the same time, part of the Fe3+ formed the Freudenbergite system. The photocatalytic activity was studied under visible light, reaching for the best catalysts a 67% and 40% mineralization degree for methylene blue and rhodamine 6G respectively, after 6 h of irradiation. In the same conditions, the well-known commercial P25 (Degussa) managed to mineralize only 12% and 3% of methylene blue and rhodamine 6G, respectively. Due to the remarkable magnetic properties of Ferrites, a convenient recovery and reuse of the catalysts is possible after the photocatalytic tests. Based on the excellent catalytic performance of the nanocomposites under visible light and their ease of separation out of the solution after the catalytic reaction, the newly developed composite catalysts are considered very effective for wastewater treatment.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000507854700130 Publication Date 2019-12-15
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0925-8388 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.2 Times cited Open Access OpenAccess
Notes The authors acknowledge the FWO-Flanders (project nr. G038215N) for financial support. Approved Most recent IF: 6.2; 2020 IF: 3.133
Call Number EMAT @ emat @c:irua:166447 Serial 6342
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