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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	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
Permanent link to this record



	Author	Rumyantseva, M.N.; Vladimirova, S.A.; Vorobyeva, N.A.; Giebelhaus, I.; Mathur, S.; Chizhov, A.S.; Khmelevsky, N.O.; Aksenenko, A.Y.; Kozlovsky, V.F.; Karakulina, O.M.; Hadermann, J.; Abakumov, A.M.; Gaskov, A.M.
	Title	p -CoO x / n -SnO 2 nanostructures: New highly selective materials for H 2 S detection			Type	A1 Journal article
	Year	2017	Publication	Sensors and actuators : B : chemical	Abbreviated Journal	Sensor Actuat B-Chem
	Volume		Issue		Pages
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	Nanostructures p-CoOx/n-SnO2 based on tin oxide nanowires have been prepared by two step CVD technique and characterized in detail by XRD, XRF, XPS, HAADF-STEM imaging and EDX-STEM mapping. Depending on the temperature of decomposition of cobalt complex during the second step of CVD synthesis of nanostructures cobalt oxide forms a coating and/or isolated nanoparticles on SnO2 nanowire surface. It was found that cobalt presents in +2 and +3 oxidation states. The measurements of gas sensor properties have been carried out during exposure to CO (14 ppm), NH3 (21 ppm), and H2S (2 ppm) in dry air. The opposite trends were observed in the effect of cobalt oxide on the SnO2 gas sensitivity when detecting CO or NH3 in comparison to H2S. The decrease of sensor signal toward CO and NH3 was attributed to high catalytic activity of Co3O4 in oxidation of these gases. Contrary, the significant increase of sensor signal in the presence of H2S was attributed to the formation of metallic cobalt sulfide and removal of the barrier between p-CoOx and n-SnO2. This effect provides an excellent selectivity of p-CoOx/n-SnO2 nanostructures in H2S detection.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000414151800068	Publication Date	2017-08-17
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0925-4005	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	5.401	Times cited	13	Open Access	Not_Open_Access: Available from 10.10.2019
	Notes	ERA-Net.Plus, 096 FONSENS ;			Approved	Most recent IF: 5.401
	Call Number	EMAT @ emat @c:irua:145926			Serial	4710
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	Author	Morozov, V.A.; Batuk, D.; Batuk, M.; Basovich, O.M.; Khaikina, E.G.; Deyneko, D.V.; Lazoryak, B.I.; Leonidov, I.I.; Abakumov, A.M.; Hadermann, J.
	Title	Luminescence Property Upgrading via the Structure and Cation Changing in Ag_xEu_(2–x)/3WO₄and Ag_xGd_{(2–x)/3–0.3}Eu_0.3WO₄			Type	A1 Journal article
	Year	2017	Publication	Chemistry of materials	Abbreviated Journal	Chem Mater
	Volume	29	Issue	20	Pages	8811-8823
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	The creation and ordering of A-cation vacancies and the effect of cation substitutions in the scheelite-type framework are investigated as a factor for controlling the scheelite-type structure and luminescence properties. AgxEu3+(2−x)/3□(1−2x)/3WO4 and AgxGd(2−x)/3−0.3Eu3+0.3□(1−2x)/3WO4 (x = 0.5−0) scheelite-type phases were synthesized by a solid state method, and their structures were investigated using a combination of transmission electron microscopy techniques and powder synchrotron X-ray diffraction. Transmission electron microscopy also revealed the (3 + 1)D incommensurately modulated character of AgxEu3+(2−x)/3□(1−2x)/3WO4 (x = 0.286, 0.2) phases. The crystal structures of the scheelite-based AgxEu3+(2−x)/3□(1−2x)/3WO4 (x = 0.5, 0.286, 0.2) red phosphors have been refined from high resolution synchrotron powder X-ray diffraction data. The luminescence properties of all phases under near-ultraviolet (n-UV) light have been investigated. The excitation spectra of AgxEu3+(2−x)/3□(1−2x)/3WO4 (x = 0.5, 0.286,0.2) phosphors show the strongest absorption at 395 nm, which matches well with the commercially available n-UV-emitting GaN-based LED chip. The excitation spectra of the Eu2/3□1/3WO4 and Gd0.367Eu0.30□1/3WO4 phases exhibit the highest contribution of the charge transfer band at 250 nm and thus the most efficient energy transfer mechanism between the host and the luminescent ion as compared to direct excitation. The emission spectra of all samples indicate an intense red emission due to the 5D0 → 7F2 transition of Eu3+. Concentration dependence of the 5D0 → 7F2 emission for AgxEu(2−x)/3□(1−2x)/3WO4 samples differs from the same dependence for the earlier studied NaxEu3+(2−x)/3□(1−2x)/3MoO4 (0 ≤ x ≤ 0.5) phases. The intensity of the 5D0 → 7F2 emission is reduced almost 7 times with decreasing x from 0.5 to 0, but it practically does not change in the range from x = 0.286 to x = 0.200. The emission spectra of Gd-containing samples show a completely different trend as compared to only Eu-containing samples. The Eu3+ emission under excitation of Eu3+(5L6) level (λex = 395 nm) increases more than 2.5 times with the increasing Gd3+ concentration from 0.2 (x = 0.5) to 0.3 (x = 0.2) in the AgxGd(2−x)/3−0.3Eu3+0.3□(1−2x)/3WO4, after which it remains almost constant for higher Gd3+ concentrations.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000413884900028	Publication Date	2017-10-24
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0897-4756	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	9.466	Times cited	7	Open Access	Not_Open_Access
	Notes	This research was supported by FWO (project G039211N), Flanders Research Foundation. V.A.M. is grateful for financial support of the Russian Foundation for Basic Research (Grant 15-03-07741). E.G.K. and O.M.B. are grateful for financial support of the Russian Foundation for Basic Research (Grants 13-03-01020 and 16-03-00510). D.V.D. is grateful for financial support of the Russian Foundation for Basic Research (Grant 16-33-00197) and the Foundation of the President of the Russian Federation (Grant MK-7926.2016.5.). We are grateful to the ESRF for granting the beamtime. Experimental support of Andy Fitch at the ID31 beamline of ESRF is kindly acknowledged.			Approved	Most recent IF: 9.466
	Call Number	EMAT @ emat @c:irua:147241			Serial	4768
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	Author	Charkin, D.O.; Plokhikh, I.V.; Kazakov, S.M.; Kalmykov, S.N.; Akinfiev, V.S.; Gorbachev, A.V.; Batuk, M.; Abakumov, A.M.; Teterin, Y.A.; Maslakov, K.I.; Teterin, A.Y.; Ivanov, K.E.
	Title	Synthesis and structural characterization of a novel Sillén – Aurivillius bismuth oxyhalide, PbBi3VO7.5Cl, and its derivatives			Type	A1 Journal article
	Year	2018	Publication	Solid state sciences	Abbreviated Journal	Solid State Sci
	Volume	75	Issue		Pages	27-33
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	A new Sillen – Aurivillius family of layered bismuth oxyhalides has been designed and successfully constructed on the basis of PbBiO2X(X = halogen) synthetic perites and g-form of Bi2VO5.5 solid elec- trolyte. This demonstrates, for the first time, the ability of the latter to serve as a building block in construction of mixed-layer structures. The parent compound PbBi3VO7.5-dCl (d = 0.05) has been investigated by powder XRD, TEM, XPS methods and magnetic susceptibility measurements. An unexpected but important condition for the formation of the mixed-layer structure is partial (ca. 5%) reduction of VV into VIV which probably suppresses competitive formation of apatite-like Pb – Bi vanadates. This reduction also stabilizes the g polymorphic form of Bi2VO5.5 not only in the intergrowth structure, but in Bi2V1-xMxO5.5-y (M – Nb, Sb) solid solutions.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000418566200005	Publication Date	2017-11-21
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1293-2558	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	1.811	Times cited	1	Open Access	Not_Open_Access
	Notes	The work was partially supported by M.V. Lomonosov Moscow State University Program of Development and Russian Science Foundation under Grant No.14-13-00738. We also thank Dr. K.V. Zakharov (MSU) for the magnetic measurements of the PbBi3- VO7.5Cl sample.			Approved	Most recent IF: 1.811
	Call Number	EMAT @ emat @c:irua:147239			Serial	4769
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	Author	Pearce, P.E.; Perez, A.J.; Rousse, G.; Saubanère, M.; Batuk, D.; Foix, D.; McCalla, E.; Abakumov, A.M.; Van Tendeloo, G.; Doublet, M.-L.; Tarascon, J.-M.
	Title	Evidence for anionic redox activity in a tridimensional-ordered Li-rich positive electrode β-Li2IrO3			Type	A1 Journal article
	Year	2017	Publication	Nature materials	Abbreviated Journal	Nat Mater
	Volume	16	Issue	5	Pages	580-586
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	Lithium-ion battery cathode materials have relied on cationic redox reactions until the recent discovery of anionic redox activity in Li-rich layered compounds which enables capacities as high as 300 mAh g(-1). In the quest for new high-capacity electrodes with anionic redox, a still unanswered question was remaining regarding the importance of the structural dimensionality. The present manuscript provides an answer. We herein report on a beta-Li2IrO3 phase which, in spite of having the Ir arranged in a tridimensional (3D) framework instead of the typical two-dimensional (2D) layers seen in other Li-rich oxides, can reversibly exchange 2.5 e(-) per Ir, the highest value ever reported for any insertion reaction involving d-metals. We show that such a large activity results from joint reversible cationic (Mn+) and anionic (O-2)(n-) redox processes, the latter being visualized via complementary transmission electron microscopy and neutron diffraction experiments, and confirmed by density functional theory calculations. Moreover, beta-Li2IrO3 presents a good cycling behaviour while showing neither cationic migration nor shearing of atomic layers as seen in 2D-layered Li-rich materials. Remarkably, the anionic redox process occurs jointly with the oxidation of Ir4+ at potentials as low as 3.4 V versus Li+/Li-0, as equivalently observed in the layered alpha-Li2IrO3 polymorph. Theoretical calculations elucidate the electrochemical similarities and differences of the 3D versus 2D polymorphs in terms of structural, electronic and mechanical descriptors. Our findings free the structural dimensionality constraint and broaden the possibilities in designing high-energy-density electrodes for the next generation of Li-ion batteries.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000400004200018	Publication Date	2017-02-27
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1476-1122	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	39.737	Times cited		Open Access	Not_Open_Access
	Notes	The authors thank Q. Jacquet for fruitful discussions and V. Pomjakushin for his valuable help in neutron diffraction experiments. This work is based on experiments performed at the Swiss Spallation Neutron Source SINQ, Paul Scherrer Institute, Villigen, Switzerland. Use of the 11-BM mail service of the APS at Argonne National Laboratory was supported by the US Department of Energy under contract No. DE-AC02-06CH11357 and is greatly acknowledged. J.-M.T. acknowledges funding from the European Research Council (ERC) (FP/2014)/ERC Grant-Project 670116-ARPEMA. E.M. acknowledges financial support from the Fonds de Recherche du Quebec-Nature et Technologies.			Approved	Most recent IF: 39.737
	Call Number	EMAT @ emat @c:irua:147502			Serial	4773
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	Author	Tsirlin, A.A.; Rousochatzakis, I.; Filimonov, D.; Batuk, D.; Frontzek, M.; Abakumov, A.M.
	Title	Spin-reorientation transitions in the Cairo pentagonal magnet Bi4Fe5O13F			Type	A1 Journal article
	Year	2017	Publication	Physical review B	Abbreviated Journal	Phys Rev B
	Volume	96	Issue	9	Pages	094420
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	We show that interlayer spins play a dual role in the Cairo pentagonal magnet Bi4Fe5O13F, on one hand mediating the three-dimensional magnetic order, and on the other driving spin-reorientation transitions both within and between the planes. The corresponding sequence of magnetic orders unraveled by neutron diffraction and Mossbauer spectroscopy features two orthogonal magnetic structures described by opposite local vector chiralities, and an intermediate, partly disordered phase with nearly collinear spins. A similar collinear phase has been predicted theoretically to be stabilized by quantum fluctuations, but Bi4Fe5O13F is very far from the relevant parameter regime. While the observed in-plane reorientation cannot be explained by any standard frustration mechanism, our ab initio band-structure calculations reveal strong single-ion anisotropy of the interlayer Fe3+ spins that turns out to be instrumental in controlling the local vector chirality and the associated interlayer order.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000411161700002	Publication Date	2017-09-19
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	2469-9950	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.836	Times cited	7	Open Access	OpenAccess
	Notes	We are grateful to J.-M. Perez-Mato and Dmitry Khalyavin for valuable discussions on the magnetic structures and symmetries. D.F. and A.A. are grateful to the Russian Science Foundation (Grant No. 14-13-00680) for support. A.T. was supported by the Federal Ministry for Education and Research through the Sofja Kovalevskaya Award of the Alexander von Humboldt Foundation. This work is based on experiments performed at the Swiss spallation neutron source SINQ, Paul Scherrer Institut, Villigen, Switzerland.			Approved	Most recent IF: 3.836
	Call Number	EMAT @ emat @c:irua:146748			Serial	4774
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	Author	Vishwakarma, M.; Karakulina, O.M.; Abakumov, A.M.; Hadermann, J.; Mehta, B.R.
	Title	Nanoscale Characterization of Growth of Secondary Phases in Off-Stoichiometric CZTS Thin Films			Type	A1 Journal article
	Year	2018	Publication	Journal of nanoscience and nanotechnology	Abbreviated Journal	J Nanosci Nanotechno
	Volume	18	Issue	3	Pages	1688-1695
	Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
	Abstract	The presence of secondary phases is one of the main issues that hinder the growth of pure kesterite Cu2ZnSnS4 (CZTS) based thin films with suitable electronic and junction properties for efficient solar cell devices. In this work, CZTS thin films with varied Zn and Sn content have been prepared by RF-power controlled co-sputtering deposition using Cu, ZnS and SnS targets and a subsequent sulphurization step. Detailed TEM investigations show that the film shows a layered structure with the majority of the top layer being the kesterite phase. Depending on the initial thin film composition, either about ~1 μm Cu-rich and Zn-poor kesterite or stoichiometric CZTS is formed as top layer. X-ray diffraction, Raman spectroscopy and transmission electron microscopy reveal the presence of Cu2−x S, ZnS and SnO2 minor secondary phases in the form of nanoinclusions or nanoparticles or intermediate layers.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000426033400022	Publication Date	2018-03-01
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1533-4880	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	1.483	Times cited		Open Access	Not_Open_Access
	Notes	Manoj Vishwakarma acknowl- edges IIT Delhi for MHRD fellowship. Professor B. R. Mehta acknowledges the support of the Schlumberger chair professorship. Manoj Vishwakarma, Joke Hadermann and Olesia M. karakulina acknowledge support provided by InsoL-DST. Manoj Vishwakarma acknowledges sup- port provided by CSIR funded projects and the support of DST-FIST Raman facility. References			Approved	Most recent IF: 1.483
	Call Number	EMAT @ emat @c:irua:147505			Serial	4775
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	Author	Niu, H.; Pitcher, M.J.; Corkett, A.J.; Ling, S.; Mandal, P.; Zanella, M.; Dawson, K.; Stamenov, P.; Batuk, D.; Abakumov, A.M.; Bull, C.L.; Smith, R.I.; Murray, C.A.; Day, S.J.; Slater, B.; Cora, F.; Claridge, J.B.; Rosseinsky, M.J.
	Title	Room Temperature Magnetically Ordered Polar Corundum GaFeO3 Displaying Magnetoelectric Coupling			Type	A1 Journal article
	Year	2017	Publication	Journal of the American Chemical Society	Abbreviated Journal	J Am Chem Soc
	Volume	139	Issue	4	Pages	1520-1531
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	The polar corundum structure type offers a route to new room temperature multiferroic materials, as the partial LiNbO3-type cation ordering that breaks inversion symmetry may be combined with long-range magnetic ordering of high spin d(5) cations above room temperature in the AFeO(3) system. We report the synthesis of a polar corundum GaFeO3 by a high-pressure, high-temperature route and demonstrate that its polarity arises from partial LiNbO3 -type cation ordering by complementary use of neutron, X-ray, and electron diffraction methods. In situ neutron diffraction shows that the polar corundum forms directly from AlFeO3-type GaFeO3 under the synthesis conditions. The A(3+)/Fe3+ cations are shown to be more ordered in polar corundum GaFeO3 than in isostructural ScFeO3. This is explained by DFT calculations which indicate that the extent of ordering is dependent on the configurational entropy available to each system at the very different synthesis temperatures required to form their corundum structures. Polar corundum GaFeO3 exhibits weak ferromagnetism at room temperature that arises from its Fe2O3-like magnetic ordering, which persists to a temperature of 408 K. We demonstrate that the polarity and magnetization are coupled in this system with a measured linear magnetoelectric coupling coefficient of 0.057 ps/m. Such coupling is a prerequisite for potential applications of polar corundum materials in multiferroic/magnetoelectric devices.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000393355600034	Publication Date	2016-12-25
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0002-7863	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	13.858	Times cited	12	Open Access	OpenAccess
	Notes	This work was funded by the EPSRC under EP/N004884. We thank the STFC for provision of beam time at ISIS and Diamond Light Source. We thank the Materials Chemistry Consortium (EPSRC, EP/L000202) for access to computer time on the ARCHER UK National Supercomputing Service (http://www.archer.ac.uk). A.M.A. is grateful to the Russian Science Foundation (Grant 14-13-00680) for financial support. MJ.R is a Royal Society Research Professor. We wish to thank Dr. Ming Li (University of Nottingham, UK) for helpful discussion and advice. Original data is available at the University of Liverpool's DataCat repository at DOI: 10.17638/datacat.liverpool.ac.uk/235. The supporting crystallographic information file may also be obtained from FIZ Karlsruhe, 76344 Eggenstein-Leopoldshafen, Germany (e-mail: crysdata@fiz-karlsruhe.de), on quoting the deposition number CSD-432419.			Approved	Most recent IF: 13.858
	Call Number	EMAT @ emat @c:irua:147507			Serial	4777
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	Author	Ulu Okudur, F.; D'Haen, J.; Vranken, T.; De Sloovere, D.; Verheijen, M.; Karakulina, O.M.; Abakumov, A.M.; Hadermann, J.; Van Bael, M.K.; Hardy, A.
	Title	Ti surface doping of LiNi_0.5Mn_1.5O_4−δpositive electrodes for lithium ion batteries			Type	A1 Journal article
	Year	2018	Publication	RSC advances	Abbreviated Journal	Rsc Adv
	Volume	8	Issue	13	Pages	7287-7300
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	The particle surface of LiNi0.5Mn1.5O4−δ (LNMO), a Li-ion battery cathode material, has been modified by Ti cation doping through a hydrolysis–condensation reaction followed by annealing in oxygen. The effect of different annealing temperatures (500–850 °C) on the Ti distribution and electrochemical performance of the surface modified LNMO was investigated. Ti cations diffuse from the preformed amorphous ‘TiOx’ layer into the LNMO surface during annealing at 500 °C. This results in a 2–4 nm thick Ti-rich spinel surface having lower Mn and Ni content compared to the core of the LNMO particles, which was observed with scanning transmission electron microscopy coupled with compositional EDX mapping. An increase in the annealing temperature promotes the formation of a Ti bulk doped LiNi(0.5−w)Mn(1.5+w)−tTitO4 phase and Ti-rich LiNi0.5Mn1.5−yTiyO4 segregates above 750 °C. Fourier-transform infrared spectrometry indicates increasing Ni–Mn ordering with annealing temperature, for both bare and surface modified LNMO. Ti surface modified LNMO annealed at 500 °C shows a superior cyclic stability, coulombic efficiency and rate performance compared to bare LNMO annealed at 500 °C when cycled at 3.4–4.9 V vs. Li/Li+. The improvements are probably due to suppressed Ni and Mn dissolution with Ti surface doping.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000425508900064	Publication Date	2018-02-13
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	2046-2069	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.108	Times cited	9	Open Access	OpenAccess
	Notes	This research is supported by the Research Foundation Flanders (FWO Vlaanderen, grant number G040116N). This project receives the support of the European Union, the European Regional Development Fund ERDF, Flanders Innovation & Entrepreneurship and the Province of Limburg (project 936). Greet Cuyvers and Gilles Bonneux (UHasselt) are acknowledged for the ICP-AES sample preparation and measurements. Vera Meynen and Karen Leyssens (Antwerp University, Belgium) are acknowledged for the BET measurements. Special thanks to Bart Ruttens (UHasselt) for XRD measurements and discussions on the refinements.			Approved	Most recent IF: 3.108
	Call Number	EMAT @ emat @c:irua:149513			Serial	4905
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	Author	Pearce, P.E.; Rousse, G.; Karakulina, O.M.; Hadermann, J.; Van Tendeloo, G.; Foix, D.; Fauth, F.; Abakumov, A.M.; Tarascon, J.-M.
	Title	β-Na_1.7IrO₃: A Tridimensional Na-Ion Insertion Material with a Redox Active Oxygen Network			Type	A1 Journal article
	Year	2018	Publication	Chemistry of materials	Abbreviated Journal	Chem Mater
	Volume	30	Issue	10	Pages	3285-3293
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	The revival of the Na-ion battery concept has prompted an intense search for new high capacity Na-based positive electrodes. Recently, emphasis has been placed on manipulating Na-based layered compounds to trigger the participation of the anionic network. We further explored this direction and show the feasibility of achieving anionic-redox activity in three-dimensional Na-based compounds. A new 3D β-Na1.7IrO3 phase was synthesized in a two-step process, which involves first the electrochemical removal of Li from β-Li2IrO3 to produce β-IrO3, which is subsequently reduced by electrochemical Na insertion. We show that β-Na1.7IrO3 can reversibly uptake nearly 1.3 Na+ per formula unit through an uneven voltage profile characterized by the presence of four plateaus related to structural transitions. Surprisingly, the β-Na1.7IrO3 phase was found to be stable up to 600 °C, while it could not be directly synthesized via conventional synthetic methods. Although these Na-based iridate phases are of limited practical interest, they help to understand how introducing highly polarizable guest ions (Na+) into host rocksalt-derived oxide structures affects the anionic redox mechanism.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000433403800014	Publication Date	2018-05-22
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0897-4756	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	9.466	Times cited	6	Open Access	OpenAccess
	Notes	The authors thank A. Perez for fruitful discussions and his valuable help in synchrotron XRD experiment and Matthieu Courty for carrying out the DSC measurements. The authors also greatly thank Matthieu Saubanère and Marie-Liesse Doublet for valuable discussions on theoretical aspects of this work. This work is based on experiments performed on the Materials Science and Powder Diffraction Beamline at ALBA synchrotron (Proposal 2016091814), Cerdanyola del Vallès, E- 08290 Barcelona, Spain. J.-M.T. acknowledges funding from the European Research Council (ERC) (FP/2014)/ERC Grant- Project 670116-ARPEMA. G.R. acknowledges funding from ANR DeliRedox. O.M.K., J.H., and A.M.A. are grateful to FWO Vlaanderen for financial support under Grant G040116N.			Approved	Most recent IF: 9.466
	Call Number	EMAT @ emat @c:irua:152048			Serial	4996
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	Author	Karakulina, O.M.; Demortière, A.; Dachraoui, W.; Abakumov, A.M.; Hadermann, J.
	Title	In Situ Electron Diffraction Tomography Using a Liquid-Electrochemical Transmission Electron Microscopy Cell for Crystal Structure Determination of Cathode Materials for Li-Ion batteries			Type	A1 Journal article
	Year	2018	Publication	Nano letters	Abbreviated Journal	Nano Lett
	Volume	18	Issue	10	Pages	6286-6291
	Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
	Abstract	We demonstrate that changes in the unit cell structure of lithium battery cathode materials during electrochemical cycling in liquid electrolyte can be determined for particles of just a few hundred nanometers in size using in situ transmission electron microscopy (TEM). The atomic coordinates, site occupancies (including lithium occupancy), and cell parameters of the materials can all be reliably quantified. This was achieved using electron diffraction tomography (EDT) in a sealed electrochemical cell with conventional liquid electrolyte (LP30) and LiFePO4 crystals, which have a well-documented charged structure to use as reference. In situ EDT in a liquid environment cell provides a viable alternative to in situ X-ray and neutron diffraction experiments due to the more local character of TEM, allowing for single crystal diffraction data to be obtained from multiphased powder samples and from submicrometer- to nanometer-sized particles. EDT is the first in situ TEM technique to provide information at the unit cell level in the liquid environment of a commercial TEM electrochemical cell. Its application to a wide range of electrochemical experiments in liquid environment cells and diverse types of crystalline materials can be envisaged.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000447355400024	Publication Date	2018-10-10
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1530-6984	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	12.712	Times cited	12	Open Access	Not_Open_Access: Available from 08.09.2019
	Notes	O.M. Karakulina, A.M. Abakumov and J. Hadermann acknowledge support from FWO under grant G040116N. A. Demortière wants to thank the French network on the electrochemical energy storage (RS2E), the Store-Ex Labex, for the financial support. Finally, the Fonds Européen de Développement Régional (FEDER), CNRS, Région Hauts-de-France, and Ministère de l’Education Nationale de l’Enseignement Supérieur et de la Recherche are acknowledged for funding.			Approved	Most recent IF: 12.712
	Call Number	EMAT @ emat @c:irua:154750			Serial	5063
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	Author	Yang, C.; Batuk, M.; Jacquet, Q.; Rousse, G.; Yin, W.; Zhang, L.; Hadermann, J.; Abakumov, A.M.; Cibin, G.; Chadwick, A.; Tarascon, J.-M.; Grimaud, A.
	Title	Revealing pH-Dependent Activities and Surface Instabilities for Ni-Based Electrocatalysts during the Oxygen Evolution Reaction			Type	A1 Journal article
	Year	2018	Publication	ACS energy letters	Abbreviated Journal	Acs Energy Lett
	Volume		Issue		Pages	2884-2890
	Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
	Abstract	Multiple electrochemical processes are involved at the catalyst/ electrolyte interface during the oxygen evolution reaction (OER). With the purpose of elucidating the complexity of surface dynamics upon OER, we systematically studied two Ni-based crystalline oxides (LaNiO3−δ and La2Li0.5Ni0.5O4) and compared them with the state-of-the-art Ni−Fe (oxy)- hydroxide amorphous catalyst. Electrochemical measurements such as rotating ring disk electrode (RRDE) and electrochemical quartz microbalance microscopy (EQCM) coupled with a series of physical characterizations including transmission electron microscopy (TEM) and X-ray absorption spectroscopy (XAS) were conducted to unravel the exact pH effect on both the OER activity and the catalyst stability. We demonstrate that for Ni-based crystalline catalysts the rate for surface degradation depends on the pH and is greater than the rate for surface reconstruction. This behavior is unlike that for the amorphous Ni oxyhydroxide catalyst, which is found to be more stable and pH-independent.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000453805100005	Publication Date	2018-11-08
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	2380-8195	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor		Times cited		Open Access	Not_Open_Access: Available from 06.11.2019
	Notes	C.Y., J.-M.T., and A.G. acknowledge funding from the European Research Council (ERC) (FP/2014)/ERC GrantProject 670116-ARPEMA. A.G. acknowledges financial support from the ANR MIDWAY (Project ID ANR-17-CE05- 0008). We acknowledge Diamond Light Source for time awarded to the Energy Materials BAG on Beamline B18, under Proposal sp12559.			Approved	Most recent IF: NA
	Call Number	EMAT @ emat @c:irua:155046			Serial	5067
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	Author	Abakumov, A.M.; Li, C.; Boev, A.; Aksyonov, D.A.; Savina, A.A.; Abakumova, T.A.; Van Tendeloo, G.; Bals, S.
	Title	Grain boundaries as a diffusion-limiting factor in lithium-rich NMC cathodes for high-energy lithium-ion batteries			Type	A1 Journal article
	Year	2021	Publication	ACS applied energy materials	Abbreviated Journal
	Volume	4	Issue	7	Pages	6777-6786
	Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
	Abstract	High-energy lithium-rich layered transition metal oxides are capable of delivering record electrochemical capacity and energy density as positive electrodes for Li-ion batteries. Their electrochemical behavior is extremely complex due to sophisticated interplay between crystal structure, electronic structure, and defect structure. Here we unravel an extra level of this complexity by revealing that the most typical representative Li1.2Ni0.13Mn0.54Co0.13O2 material, prepared by a conventional coprecipitation technique with Na2CO3 as a precipitating agent, contains abundant coherent (001) grain boundaries with a Na-enriched P2-structured block due to segregation of the residual sodium traces. The trigonal prismatic oxygen coordination of Na triggers multiple nanoscale twinning, giving rise to incoherent (104) boundaries. The cationic layers at the (001) grain boundaries are filled with transition metal cations being Mn-depleted and Co-enriched; this makes them virtually not permeable for the Li+ cations, and therefore they negatively influence the Li diffusion in and out of the spherical agglomerates. These results demonstrate that besides the mechanisms intrinsic to the crystal and electronic structure of Li-rich cathodes, their rate capability might also be depreciated by peculiar microstructural aspects. Dedicated engineering of grain boundaries opens a way for improving inherently sluggish kinetics of these materials.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000678382900042	Publication Date	2021-07-02
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	2574-0962	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor		Times cited	4	Open Access	OpenAccess
	Notes	We thank Dr. M. V. Berekchiian (MSU) for assisting in ICPMS measurements. We acknowledge Russian Science Foundation (Grant 20-43-01012) and Research Foundation Flanders (FWO Vlaanderen, Project No. G0F1320N) for financial support.			Approved	Most recent IF: NA
	Call Number	UA @ admin @ c:irua:180556			Serial	6841
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	Author	Paulus, A.; Hendrickx, M.; Mayda, S.; Batuk, M.; Reekmans, G.; von Holst, M.; Elen, K.; Abakumov, A.M.; Adriaensens, P.; Lamoen, D.; Partoens, B.; Hadermann, J.; Van Bael, M.K.; Hardy, A.
	Title	Understanding the Activation of Anionic Redox Chemistry in Ti⁴⁺-Substituted Li₂MnO₃as a Cathode Material for Li-Ion Batteries			Type	A1 Journal article
	Year	2023	Publication	ACS applied energy materials	Abbreviated Journal	ACS Appl. Energy Mater.
	Volume	6	Issue	13	Pages	6956-6971
	Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	Layered Li-rich oxides, demonstrating both cationic and anionic redox chemistry being used as positive electrodes for Li-ion batteries,have raised interest due to their high specific discharge capacities exceeding 250 mAh/g. However, irreversible structural transformations triggered by anionic redox chemistry result in pronounced voltagefade (i.e., lowering the specific energy by a gradual decay of discharge potential) upon extended galvanostatic cycling. Activating or suppressing oxygen anionic redox through structural stabilization induced by redox-inactivecation substitution is a well-known strategy. However, less emphasishas been put on the correlation between substitution degree and theactivation/suppression of the anionic redox. In this work, Ti4+-substituted Li2MnO3 was synthesizedvia a facile solution-gel method. Ti4+ is selected as adopant as it contains no partially filled d-orbitals. Our study revealedthat the layered “honeycomb-ordered” C2/m structure is preserved when increasing the Ticontent to x = 0.2 in the Li2Mn1-x Ti (x) O-3 solidsolution, as shown by electron diffraction and aberration-correctedscanning transmission electron microscopy. Galvanostatic cycling hintsat a delayed oxygen release, due to an improved reversibility of theanionic redox, during the first 10 charge-discharge cyclesfor the x = 0.2 composition compared to the parentmaterial (x = 0), followed by pronounced oxygen redoxactivity afterward. The latter originates from a low activation energybarrier toward O-O dimer formation and Mn migration in Li2Mn0.8Ti0.2O3, as deducedfrom first-principles molecular dynamics (MD) simulations for the“charged” state. Upon lowering the Ti substitution to x = 0.05, the structural stability was drastically improvedbased on our MD analysis, stressing the importance of carefully optimizingthe substitution degree to achieve the best electrochemical performance.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	001018266700001	Publication Date	2023-07-10
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	2574-0962	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	6.4	Times cited		Open Access	Not_Open_Access: Available from 24.12.2023
	Notes	Universiteit Hasselt, AUHL/15/2 – GOH3816N ; Russian Science Foundation, 20-43-01012 ; Fonds Wetenschappelijk Onderzoek, AUHL/15/2 – GOH3816N G040116N ; The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center) and the HPC infrastructure of the University of Antwerp (CalcUA), both funded by the FWO Vlaanderen and the Flemish Government-department EWI.			Approved	Most recent IF: 6.4; 2023 IF: NA
	Call Number	EMAT @ emat @c:irua:198160			Serial	8809
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	Author	Tyablikov, O.A.; Batuk, D.; Tsirlin, A.A.; Batuk, M.; Verchenko, V.Y.; Filimonov, D.S.; Pokholok, K.V.; Sheptyakov, D.V.; Rozova, M.G.; Hadermann, J.; Antipov, E.V.; Abakumov, A.M.;
	Title	{110}-Layered B-cation ordering in the anion-deficient perovskite Pb_2.4Ba_2.6Fe₂Sc₂TiO₁₃ with the crystallographic shear structure			Type	A1 Journal article
	Year	2015	Publication	Journal of the Chemical Society : Dalton transactions	Abbreviated Journal	Dalton T
	Volume	44	Issue	44	Pages	10753-10762
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	A novel anion-deficient perovskite-based compound, Pb2.4Ba2.6Fe2Sc2TiO13, was synthesized via the citrate-based route. This compound is an n = 5 member of the A(n)B(n)O(3n-2) homologous series with unit-cell parameters related to the perovskite subcell a(p) approximate to 4.0 angstrom as a(p)root 2 x a(p) x 5a(p)root 2. The crystal structure of Pb2.4Ba2.6Fe2Sc2TiO13 consists of quasi-2D perovskite blocks with a thickness of three octahedral layers separated by the 1/2[110]((1) over bar 01)(p) crystallographic shear (CS) planes, which are parallel to the {110} plane of the perovskite subcell. The CS planes transform the corner-sharing octahedra into chains of edge-sharing distorted tetragonal pyramids. Using a combination of neutron powder diffraction, Fe-57 Mossbauer spectroscopy and atomic resolution electron energy-loss spectroscopy we demonstrate that the B-cations in Pb2.4Ba2.6Fe2Sc2TiO13 are ordered along the {110} perovskite layers with Fe3+ in distorted tetragonal pyramids along the CS planes, Ti4+ preferentially in the central octahedra of the perovskite blocks and Sc3+ in the outer octahedra of the perovskite blocks. Magnetic susceptibility and Mossbauer spectroscopy indicate a broadened magnetic transition around T-N similar to 45 K and the onset of local magnetic fields at low temperatures. The magnetic order is probably reminiscent of that in other A(n)B(n)O(3n-2) homologues, where G-type AFM order within the perovskite blocks has been observed.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	London	Editor
	Language		Wos	000355701000026	Publication Date	2015-01-26
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1477-9226;1477-9234;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	4.029	Times cited	1	Open Access
	Notes				Approved	Most recent IF: 4.029; 2015 IF: 4.197
	Call Number	c:irua:127001			Serial	22
Permanent link to this record



	Author	Van Tendeloo, G.; Hadermann, J.; Abakumov, A.M.; Antipov, E.V.
	Title	Advanced electron microscopy and its possibilities to solve complex structures: application to transition metal oxides			Type	A1 Journal article
	Year	2009	Publication	Journal of materials chemistry	Abbreviated Journal	J Mater Chem
	Volume	19	Issue	18	Pages	2660-2670
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	Design and optimization of materials properties can only be performed through a thorough knowledge of the structure of the compound. In this feature article we illustrate the possibilities of advanced electron microscopy in materials science and solid state chemistry. The different techniques are briefly discussed and several examples are given where the structures of complex oxides, often with a modulated structure, have been solved using electron microscopy.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Cambridge	Editor
	Language		Wos	000265740600002	Publication Date	2009-02-04
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0959-9428;1364-5501;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor		Times cited	9	Open Access
	Notes				Approved	Most recent IF: NA
	Call Number	UA @ lucian @ c:irua:77065			Serial	68
Permanent link to this record



	Author	Sun, M.; Rousse, G.; Abakumov, A.M.; Van Tendeloo, G.; Sougrati, M.-T.; Courty, M.; Doublet, M.-L.; Tarascon, J.-M.
	Title	An oxysulfate Fe₂O(SO₄)₂ electrode for sustainable Li-based batteries			Type	A1 Journal article
	Year	2014	Publication	Journal of the American Chemical Society	Abbreviated Journal	J Am Chem Soc
	Volume	136	Issue	36	Pages	12658-12666
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	High-performing Fe-based electrodes for Li-based batteries are eagerly pursued because of the abundance and environmental benignity of iron, with especially great interest in polyanionic compounds because of their flexibility in tuning the Fe3+/Fe2+ redox potential. We report herein the synthesis and structure of a new Fe-based oxysulfate phase, Fe2O(SO4)(2), made at low temperature from abundant elements, which electrochemically reacts with nearly 1.6 Li atoms at an average voltage of 3.0 V versus Li+/Li, leading to a sustained reversible capacity of similar to 125 mAh/g. The Li insertiondeinsertion process, the first ever reported in any oxysulfate, entails complex phase transformations associated with the position of iron within the FeO6 octahedra. This finding opens a new path worth exploring in the quest for new positive electrode materials.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Washington, D.C.	Editor
	Language		Wos	000341544600029	Publication Date	2014-08-14
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0002-7863;1520-5126;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	13.858	Times cited	11	Open Access
	Notes				Approved	Most recent IF: 13.858; 2014 IF: 12.113
	Call Number	UA @ lucian @ c:irua:119906			Serial	96
Permanent link to this record



	Author	Abakumov, A.M.; Hadermann, J.; Van Tendeloo, G.; Shpanchenko, R.V.; Oleinikov, P.N.; Antipov, E.V.
	Title	Anion ordering in fluorinated La2CuO4			Type	A1 Journal article
	Year	1999	Publication	Journal of solid state chemistry	Abbreviated Journal	J Solid State Chem
	Volume	142	Issue		Pages	311-322
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	London	Editor
	Language		Wos	000078597400024	Publication Date	2002-10-07
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0022-4596;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.299	Times cited	20	Open Access
	Notes				Approved	Most recent IF: 2.299; 1999 IF: 1.547
	Call Number	UA @ lucian @ c:irua:29277			Serial	121
Permanent link to this record



	Author	Hadermann, J.; Abakumov, A.M.; Van Tendeloo, G.; Shpanchenko, R.V.; Oleinikov, P.N.; Antipov, E.V.
	Title	Anion ordering in fluorinated La2CuO4			Type	H1 Book chapter
	Year	1999	Publication		Abbreviated Journal
	Volume		Issue		Pages	133-138
	Keywords	H1 Book chapter; Electron microscopy for materials research (EMAT)
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	s.l.	Editor
	Language		Wos	000079308200022	Publication Date	0000-00-00
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Additional Links	UA library record; WoS full record;
	Impact Factor		Times cited		Open Access
	Notes				Approved	Most recent IF: NA
	Call Number	UA @ lucian @ c:irua:29278			Serial	122
Permanent link to this record



	Author	Corbel, G.; Attfield, J.P.; Hadermann, J.; Abakumov, A.M.; Alekseeva, A.M.; Rozova, M.G.; Antipov, E.V.
	Title	Anion rearrangements in fluorinated Nd₂CuO_3.5			Type	A1 Journal article
	Year	2003	Publication	Chemistry of materials	Abbreviated Journal	Chem Mater
	Volume	15	Issue		Pages	189-195
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Washington, D.C.	Editor
	Language		Wos	000180368000029	Publication Date	2003-01-07
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0897-4756;1520-5002;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	9.466	Times cited	9	Open Access
	Notes				Approved	Most recent IF: 9.466; 2003 IF: 4.374
	Call Number	UA @ lucian @ c:irua:40348			Serial	123
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	Author	Abakumov, A.M.; Batuk, D.; Hadermann, J.; Rozova, M.G.; Sheptyakov, D.V.; Tsirlin, A.A.; Niermann, D.; Waschowski, F.; Hemberger, J.; Van Tendeloo, G.; Antipov, E.V.
	Title	Antiferroelectric (Pb,Bi)_1-xFe_1+xO_3-y perovskites modulated by crystallographic shear planes			Type	A1 Journal article
	Year	2011	Publication	Chemistry of materials	Abbreviated Journal	Chem Mater
	Volume	23	Issue	2	Pages	255-265
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	We demonstrate for the first time a possibility to vary the anion content in perovskites over a wide range through a long-range-ordered arrangement of crystallographic shear (CS) planes. Anion-deficient perovskites (Pb,Bi)1−xFe1+xO3−y with incommensurately modulated structures were prepared as single phases in the compositional range from Pb0.857Bi0.094Fe1.049O2.572 to Pb0.409Bi0.567Fe1.025O2.796. Using a combination of electron diffraction and high-resolution scanning transmission electron microscopy, we constructed a superspace model describing a periodic arrangement of the CS planes. The model was verified by refinement of the Pb0.64Bi0.32Fe1.04O2.675 crystal structure from neutron powder diffraction data ((3 + 1)D S.G. X2/m(α0γ), X = [1/2,1/2,1/2,1/2], a = 3.9082(1) Å, b = 3.90333(8) Å, c = 4.0900(1) Å, β = 91.936(2)°, q = 0.05013(4)a* + 0.09170(3)c* at T = 700 K, RP = 0.036, RwP = 0.048). The (Pb,Bi)1−xFe1+xO3−y structures consist of perovskite blocks separated by CS planes confined to nearly the (509)p perovskite plane. Along the CS planes, the perovskite blocks are shifted with respect to each other over the 1/2[110]p vector that transforms the corner-sharing connectivity of the FeO6 octahedra in the perovskite framework to an edge-sharing connectivity of the FeO5 pyramids at the CS plane, thus reducing the oxygen content. Variation of the chemical composition in the (Pb,Bi)1−xFe1+xO3−y series occurs mainly because of a changing thickness of the perovskite block between the interfaces, that can be expressed through the components of the q vector as Pb6γ+2αBi1−7γ−αFe1+γ−αO3−3γ−α. The Pb, Bi, and Fe atoms are subjected to strong displacements occurring in antiparallel directions on both sides of the perovskite blocks, resulting in an antiferroelectric-type structure. This is corroborated by the temperature-, frequency-, and field-dependent complex permittivity measurements. Pb0.64Bi0.32Fe1.04O2.675 demonstrates a remarkably high resistivity >0.1 T Ω cm at room temperature and orders antiferromagnetically below TN = 608(10) K.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Washington, D.C.	Editor
	Language		Wos	000286160800018	Publication Date	2010-12-23
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0897-4756;1520-5002;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	9.466	Times cited	29	Open Access
	Notes				Approved	Most recent IF: 9.466; 2011 IF: 7.286
	Call Number	UA @ lucian @ c:irua:88651			Serial	136
Permanent link to this record



	Author	Belik, A.A.; Abakumov, A.M.; Tsirlin, A.A.; Hadermann, J.; Kim, J.; Van Tendeloo, G.; Takayama-Muromachi, E.
	Title	Article Structure and magnetic properties of BiFe_0.75Mn_0.25O₃ perovskite prepared at ambient and high pressure			Type	A1 Journal article
	Year	2011	Publication	Chemistry of materials	Abbreviated Journal	Chem Mater
	Volume	23	Issue	20	Pages	4505-4514
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	Solid solutions of BiFe1xMnxO3 (0.0 ≤ x ≤ 0.4) were prepared at ambient pressure and at 6 GPa. The ambient-pressure (AP) phases crystallize in space group R3c similarly to BiFeO3. The high-pressure (HP) phases crystallize in space group R3c for x = 0.05 and in space group Pnma for 0.15 ≤ x ≤ 0.4. The structure of HP-BiFe0.75Mn0.25O3 was investigated using synchrotron X-ray powder diffraction, electron diffraction, and transmission electron microscopy. HP-BiFe0.75Mn0.25O3 has a PbZrO3-related √2ap × 4ap × 2√2ap (ap is the parameter of the cubic perovskite subcell) superstructure with a = 5.60125(9) Å, b = 15.6610(2) Å, and c = 11.2515(2) Å similar to that of Bi0.82La0.18FeO3. A remarkable feature of this structure is the unconventional octahedral tilt system, with the primary ab0a tilt superimposed on pairwise clockwise and counterclockwise rotations around the b-axis according to the oioi sequence (o stands for out-of-phase tilt, and i stands for in-phase tilt). The (FeMn)O6 octahedra are distorted, with one longer metaloxygen bond (2.222.23 Å) that can be attributed to a compensation for covalent BiO bonding. Such bonding results in the localization of the lone electron pair on Bi3+ cations, as confirmed by electron localization function analysis. The relationship between HP-BiFe0.75Mn0.25O3 and antiferroelectric structures of PbZrO3 and NaNbO3 is discussed. On heating in air, HP-BiFe0.75Mn0.25O3 irreversibly transforms to AP-BiFe0.75Mn0.25O3 starting from about 600 K. Both AP and HP phases undergo an antiferromagnetic ordering at TN ≈ 485 and 520 K, respectively, and develop a weak net magnetic moment at low temperatures. Additionally, ceramic samples of AP-BiFe0.75Mn0.25O3 show a peculiar phenomenon of magnetization reversal.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Washington, D.C.	Editor
	Language		Wos	000295897400015	Publication Date	2011-09-29
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0897-4756;1520-5002;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	9.466	Times cited	57	Open Access
	Notes				Approved	Most recent IF: 9.466; 2011 IF: 7.286
	Call Number	UA @ lucian @ c:irua:93581			Serial	151
Permanent link to this record



	Author	Batuk, M.; Turner, S.; Abakumov, A.M.; Batuk, D.; Hadermann, J.; Van Tendeloo, G.
	Title	Atomic structure of defects in anion-deficient perovskite-based ferrites with a crystallographic shear structure			Type	A1 Journal article
	Year	2014	Publication	Inorganic chemistry	Abbreviated Journal	Inorg Chem
	Volume	53	Issue	4	Pages	2171-2180
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	Crystallographic shear (CS) planes provide a new structure-generation mechanism in the anion-deficient perovskites containing lone-pair cations. Pb2Sr2Bi2Fe6O16, a new n = 6 representative of the AnBnO3n2 homologous series of the perovskite-based ferrites with the CS structure, has been synthesized using the solid-state technique. The structure is built of perovskite blocks with a thickness of four FeO6 octahedra spaced by double columns of FeO5 edge-sharing distorted tetragonal pyramids, forming 1/2[110](101)p CS planes (space group Pnma, a = 5.6690(2) Å, b = 3.9108(1) Å, c = 32.643(1) Å). Pb2Sr2Bi2Fe6O16 features a wealth of microstructural phenomena caused by the flexibility of the CS planes due to the variable ratio and length of the constituting fragments with {101}p and {001}p orientation. This leads to the formation of waves, hairpins, Γ-shaped defects, and inclusions of the hitherto unknown layered anion-deficient perovskites Bi2(Sr,Pb)Fe3O8.5 and Bi3(Sr,Pb)Fe4O11.5. Using a combination of diffraction, imaging, and spectroscopic transmission electron microscopy techniques this complex microstructure was fully characterized, including direct determination of positions, chemical composition, and coordination number of individual atomic species. The complex defect structure makes these perovskites particularly similar to the CS structures in ReO3-type oxides. The flexibility of the CS planes appears to be a specific feature of the Sr-based system, related to the geometric match between the SrO perovskite layers and the {100}p segments of the CS planes.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Easton, Pa	Editor
	Language		Wos	000332144100039	Publication Date	2014-01-30
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0020-1669;1520-510X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	4.857	Times cited	6	Open Access
	Notes	Countatoms; FWO			Approved	Most recent IF: 4.857; 2014 IF: 4.762
	Call Number	UA @ lucian @ c:irua:113507			Serial	198
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	Author	Abakumov, A.M.; Morozov, V.A.; Tsirlin, A.A.; Verbeeck, J.; Hadermann, J.
	Title	Cation ordering and flexibility of the BO₄^2- tetrahedra in incommensurately modulated CaEu₂(BO₄)₄ (B = Mo, W) scheelites			Type	A1 Journal article
	Year	2014	Publication	Inorganic chemistry	Abbreviated Journal	Inorg Chem
	Volume	53	Issue	17	Pages	9407-9415
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	The factors mediating cation ordering in the scheelite-based molybdates and tungstates are discussed on the basis of the incommensurately modulated crystal structures of the CaEu2(BO4)(4) (B = Mo, W) red phosphors solved from high-resolution synchrotron powder X-ray diffraction data. Monoclinic CaEu2(WO4)(4) adopts a (3 + 1)-dimensionally modulated structure [superspace group I2/b(alpha beta 0)00, a = 5.238 73(1)A, b = 5.266 35(1) A, c = 11.463 19(9) A, gamma = 91.1511(2)degrees, q = 0.56153(6)a* + 0.7708(9)b, R-F = 0.050, R-p = 0.069], whereas tetragonal CaEu2(MoO4)(4) is (3 + 2)-dimensionally modulated [superspace group I4(1)/ a(alpha beta 0)00(-beta alpha 0)00, a = 5.238 672(7) A, c = 11.548 43(2) A, q(1) = 035331(8)a + 0.82068(9)b, q(2) = -0.82068(9)a + 0.55331(8)b*, R-F = 0.061, R-p = 0.082]. In both cases the modulation arises from the ordering of the Ca/Eu cations and the cation vacancies at the A-sublattice of the parent scheelite ABO(4) structure. The cation ordering is incomplete and better described with harmonic rather than with steplike occupational modulation functions. The structures respond to the variation of the effective charge and cation size at the A-position through the flexible geometry of the MoO42- and WO42- tetrahedra demonstrating an alternation of stretching the B-O bond lengths and bending the O-B-O bond angles. The tendency towards A-site cation ordering in scheelites is rationalized using the difference in ionic radii and concentration of the A-site vacancies as parameters and presented in the form of a structure map.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Easton, Pa	Editor
	Language		Wos	000341229600068	Publication Date	2014-08-21
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0020-1669;1520-510X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	4.857	Times cited	48	Open Access
	Notes	Fwo G039211n			Approved	Most recent IF: 4.857; 2014 IF: 4.762
	Call Number	UA @ lucian @ c:irua:119292UA @ admin @ c:irua:119292			Serial	297
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	Author	Kirsanova, M.A.; Mori, T.; Maruyama, S.; Abakumov, A.M.; Van Tendeloo, G.; Olenev, A.; Shevelkov, A.V.
	Title	Cationic clathrate of type-III Ge_172-xP_xTe_y (y\approx21,5, x\approx2y) : synthesis, crystal structure and thermoelectric properties			Type	A1 Journal article
	Year	2013	Publication	Inorganic chemistry	Abbreviated Journal	Inorg Chem
	Volume	52	Issue	14	Pages	8272-8279
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	A first germanium-based cationic clathrate of type-III, Ge129.3P42.7Te21.53, was synthesized and structurally characterized (space group P42/mnm, a = 19.948(3) Å, c = 10.440(2) Å, Z = 1). In its crystal structure, germanium and phosphorus atoms form three types of polyhedral cages centered with Te atoms. The polyhedra share pentagonal and hexagonal faces to form a 3D framework. Despite the complexity of the crystal structure, the Ge129.3P42.7Te21.53 composition corresponds to the Zintl counting scheme with a good accuracy. Ge129.3P42.7Te21.53 demonstrates semiconducting/insulating behavior of electric resistivity, high positive Seebeck coefficient (500 μV K1 at 300 K), and low thermal conductivity (<0.92 W m1 K1) within the measured temperature range.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Easton, Pa	Editor
	Language		Wos	000322087100052	Publication Date	2013-06-26
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0020-1669;1520-510X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	4.857	Times cited	3	Open Access
	Notes	Countatoms			Approved	Most recent IF: 4.857; 2013 IF: 4.794
	Call Number	UA @ lucian @ c:irua:109214			Serial	301
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	Author	Abakumov, A.M.; Hadermann, J.; Van Tendeloo, G.; Antipov, E.V.
	Title	Chemistry and structure of anion-deficient perovskites with translational interfaces			Type	A1 Journal article
	Year	2008	Publication	Journal of the American Ceramic Society	Abbreviated Journal	J Am Ceram Soc
	Volume	91	Issue	6	Pages	1807-1813
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Columbus, Ohio	Editor
	Language		Wos	000256410700010	Publication Date	2008-04-29
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0002-7820;1551-2916;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.841	Times cited	39	Open Access
	Notes				Approved	Most recent IF: 2.841; 2008 IF: 2.101
	Call Number	UA @ lucian @ c:irua:70088			Serial	355
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	Author	Hadermann, J.; Abakumov, A.M.; Van Rompaey, S.; Mankevich, A.S.; Korsakov, I.E.
	Title	Comment on ALaMn₂O_6-y (A = K, Rb): novel ferromagnetic manganites exhibiting negative giant magnetoresistance			Type	Editorial
	Year	2009	Publication	Chemistry of materials	Abbreviated Journal	Chem Mater
	Volume	21	Issue	9	Pages	2000-2001
	Keywords	Editorial; Electron microscopy for materials research (EMAT)
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Washington, D.C.	Editor
	Language		Wos	000265781000036	Publication Date	2009-04-14
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0897-4756;1520-5002;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	9.466	Times cited	4	Open Access
	Notes				Approved	Most recent IF: 9.466; 2009 IF: 5.368
	Call Number	UA @ lucian @ c:irua:77055			Serial	411
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	Author	Abakumov, A.M.; Kalyuzhnaya, A.S.; Rozova, M.G.; Antipov, E.V.; Hadermann, J.; Van Tendeloo, G.
	Title	Compositionally induced phase transition in the Ca₂MnGa_1-xAl_xO₅ solid solutions: ordering of tetrahedral chains in brownmillerite structure			Type	A1 Journal article
	Year	2005	Publication	Solid state sciences	Abbreviated Journal	Solid State Sci
	Volume	7	Issue	7	Pages	801-811
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Amsterdam	Editor
	Language		Wos	000230259500001	Publication Date	2005-04-30
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1293-2558;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	1.811	Times cited	38	Open Access
	Notes	IAP V-1; RFBR 04-03-32785-a.			Approved	Most recent IF: 1.811; 2005 IF: 1.708
	Call Number	UA @ lucian @ c:irua:54700			Serial	448
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	Author	Abakumov, A.M.; d' Hondt, H.; Rossell, M.D.; Tsirlin, A.A.; Gutnikova, O.; Filimonov, D.S.; Schnelle, W.; Rosner, H.; Hadermann, J.; Van Tendeloo, G.; Antipov, E.V.
	Title	Coupled anion and cation ordering in Sr₃RFe₄O_10.5 (R=Y, Ho, Dy) anion-deficientperovskites			Type	A1 Journal article
	Year	2010	Publication	Journal of solid state chemistry	Abbreviated Journal	J Solid State Chem
	Volume	183	Issue	12	Pages	2845-2854
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	The Sr3RFe4O10.5 (R=Y, Ho, Dy) anion-deficient perovskites were prepared using a solid-state reaction in evacuated sealed silica tubes. Transmission electron microscopy and 57Fe Mössbauer spectroscopy evidenced a complete A-cations and oxygen vacancies ordering. The structure model was further refined by ab initio structure relaxation, based on density functional theory calculations. The compounds crystallize in a tetragonal a≈2√2ap≈11.3 Å, с≈4сp≈16 Å unit cell (ap: parameter of the perovskite subcell) with the P42/mnm space group. Oxygen vacancies reside in the (FeO5/4□3/4) layers, comprising corner-sharing FeO4 tetrahedra and FeO5 tetragonal pyramids, which are sandwiched between the layers of the FeO6 octahedra. Smaller R atoms occupy the 9-fold coordinated position, whereas the 10-fold coordinated positions are occupied by larger Sr atoms. The Fe sublattice is ordered aniferromagnetically up to at least 500 K, while the rare-earth sublattice remains disordered down to 2 K.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	London	Editor
	Language		Wos	000285431100014	Publication Date	2010-10-02
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0022-4596;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.299	Times cited	8	Open Access
	Notes				Approved	Most recent IF: 2.299; 2010 IF: 2.261
	Call Number	UA @ lucian @ c:irua:88071			Serial	533
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	Author	Hadermann, J.; Abakumov, A.M.; Gillie, L.J.; Martin, C.; Hervieu, M.
	Title	Coupled cation and charge ordering in the CaMn306 tunnel structure			Type	A1 Journal article
	Year	2006	Publication	Chemistry of materials	Abbreviated Journal	Chem Mater
	Volume	18	Issue	23	Pages	5530-5536
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Washington, D.C.	Editor
	Language		Wos	000241808600021	Publication Date	2006-10-15
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0897-4756;1520-5002;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	9.466	Times cited	33	Open Access
	Notes	Iap V-1			Approved	Most recent IF: 9.466; 2006 IF: 5.104
	Call Number	UA @ lucian @ c:irua:61374			Serial	534
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