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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
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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
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Author	Kirsanova, M.A.; Olenev, A.V.; Abakumov, A.M.; Bykov, M.A.; Shevelkov, A.V.
Title	Extension of the clathrate family : the type X clathrate Ge₇₉P₂₉S₁₈Te₆			Type	A1 Journal article
Year	2011	Publication	Angewandte Chemie: international edition in English	Abbreviated Journal	Angew Chem Int Edit
Volume	50	Issue	10	Pages	2371-2374
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Now they are 10! The title compound displays a new type of crystal structure and is labeled clathrate X according to the general classification of clathrate structures. In contrast to typical clathrates, this compound has three-coordinate atoms within the framework and combines distorted 24-vertex polyhedra (see picture, green) centered around tellurium guest atoms with very irregular 10-vertex polyhedra around sulfur atoms (yellow).
Address
Corporate Author				Thesis
Publisher		Place of Publication	Weinheim	Editor
Language		Wos	000288036300033	Publication Date	2011-01-31
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	1433-7851;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	11.994	Times cited	23	Open Access
Notes				Approved	Most recent IF: 11.994; 2011 IF: 13.455
Call Number	UA @ lucian @ c:irua:88793			Serial	1158
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Author	Navulla, A.; Tsirlin, A.A.; Abakumov, A.M.; Shpanchenko, R.V.; Zhang, H.; Dikarev, E.V.
Title	Fluorinated heterometallic \beta-diketonates as volatile single-source precursors for the synthesis of low-valent mixed-metal fluorides			Type	A1 Journal article
Year	2011	Publication	Journal of the American Chemical Society	Abbreviated Journal	J Am Chem Soc
Volume	133	Issue	4	Pages	692-694
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Hexafluoroacetylacetonates that contain lead and divalent first-row transition metals, PbM(hfac)4 (M = Ni (1), Co (2), Mn (3), Fe (4), and Zn (5)), have been synthesized. Their heterometallic structures are held together by strong Lewis acid−base interactions between metal atoms and diketonate ligands acting in chelating−bridging fashion. Compounds 1−5 are highly volatile and decompose below 350 °C. Fluorinated heterometallic β-diketonates have been used for the first time as volatile single-source precursors for the preparation of mixed-metal fluorides. Complex fluorides of composition Pb2MF6 have been obtained by decomposition of 1−5 in a two-zone furnace under low-pressure nitrogen flow. Lead−transition metal fluorides conform to orthorhombically distorted Aurivillius-type structure with layers of corner-sharing [MF6] octahedra separated by α-PbO-type (Pb2F2) blocks. Pb2NiF6 and Pb2CoF6 were found to exhibit magnetic ordering below 80 and 43 K, respectively. The ordering is antiferromagnetic, with a weak, uncompensated moment due to the canting of spins. The Pb2MF6 fluorides represent a new class of prospective magnetoelectric materials combining transition metals and lone-pair main-group cations.
Address
Corporate Author				Thesis
Publisher		Place of Publication	Washington, D.C.	Editor
Language		Wos	000287295300015	Publication Date	2010-12-21
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	28	Open Access
Notes				Approved	Most recent IF: 13.858; 2011 IF: 9.907
Call Number	UA @ lucian @ c:irua:88820			Serial	1236
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Author	King, G.; Abakumov, A.M.; Woodward, P.M.; Llobet, A.; Tsirlin, A.A.; Batuk, D.; Antipov, E.V.
Title	The high-temperature polymorphs of K₃AlF₆			Type	A1 Journal article
Year	2011	Publication	Inorganic chemistry	Abbreviated Journal	Inorg Chem
Volume	50	Issue	16	Pages	7792-7801
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	The crystal structures of the three high-temperature polymorphs of K3AlF6 have been solved from neutron powder diffraction, synchrotron X-ray powder diffraction, and electron diffraction data. The β-phase (stable between 132 and 153 °C) and γ-phase (stable between 153 to 306 °C) can be described as unusually complex superstructures of the double-perovskite structure (K2KAlF6) which result from noncooperative tilting of the AlF6 octahedra. The β-phase is tetragonal, space group I4/m, with lattice parameters of a = 13.3862(5) Å and c = 8.5617(3) Å (at 143 °C) and Z = 10. In this phase, one-fifth of the AlF6 octahedra are rotated about the c-axis by 45° while the other four-fifths remain untilted. The large 45° rotations result in edge sharing between these AlF6 octahedra and the neighboring K-centered polyhedra, resulting in pentagonal bipyramidal coordination for four-fifths of the K+ ions that reside on the B-sites of the perovskite structure. The remaining one-fifth of the K+ ions on the B-sites retain octahedral coordination. The γ-phase is orthorhombic, space group Fddd, with lattice parameters of a = 36.1276(4) Å, b = 17.1133(2) Å, and c = 12.0562(1) Å (at 225 °C) and Z = 48. In the γ-phase, one-sixth of the AlF6 octahedra are randomly rotated about one of two directions by 45° while the other five-sixths remain essentially untilted. These rotations result in two-thirds of the K+ ions on the B-site obtaining 7-fold coordination while the other one-third remain in octahedral coordination. The δ-phase adopts the ideal cubic double-perovskite structure, space group Fmm, with a = 8.5943(1) Å at 400 °C. However, pair distribution function analysis shows that locally the δ-phase is quite different from its long-range average crystal structure. The AlF6 octahedra undergo large-amplitude rotations which are accompanied by off-center displacements of the K+ ions that occupy the 12-coordinate A-sites.
Address
Corporate Author				Thesis
Publisher		Place of Publication	Easton, Pa	Editor
Language		Wos	000293493100052	Publication Date	2011-07-11
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	19	Open Access
Notes				Approved	Most recent IF: 4.857; 2011 IF: 4.601
Call Number	UA @ lucian @ c:irua:91131			Serial	1468
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Author	Batuk, D.; Hadermann, J.; Abakumov, A.; Vranken, T.; Hardy, A.; van Bael, M.; Van Tendeloo, G.
Title	Layered perovskite-like Pb₂Fe₂O₅ structure as a parent matrix for the nucleation and growth of crystallographic shear planes			Type	A1 Journal article
Year	2011	Publication	Inorganic chemistry	Abbreviated Journal	Inorg Chem
Volume	50	Issue	11	Pages	4978-4986
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	The Pb2Fe2O5 compound with a layered intergrowth structure has been prepared by a solid-state reaction at 700 °C. The incommensurate compound crystallizes in a tetragonal system with a = 3.9037(2) Å, c = 3.9996(4) Å, and q = 0.1186(4)c*, or when treated as a commensurate approximant, a = 3.9047(2) Å, c = 36.000(3) Å, space group I4/mmm. The crystal structure of Pb2Fe2O5 was resolved from transmission electron microscopy data. Atomic coordinates and occupancies of the cation positions were estimated from high-angle annular dark-field scanning transmission electron microscopy data. Direct visualization of the positions of the oxygen atoms was possible using annular bright-field scanning transmission electron microscopy. The structure can be represented as an intergrowth of perovskite blocks and partially disordered blocks with a structure similar to that of the Bi2O2 blocks in Aurivillius-type phases. The A-cation positions at the border of the perovskite block and the cation positions in the Aurivillius-type blocks are jointly occupied by Pb2+ and Fe3+ cations, resulting in a layer sequence along the c axis: PbOFeO2PbOFeO2Pb7/8Fe1/8O1xFe5/8Pb3/8O2Fe5/8Pb3/8. Upon heating, the layered Pb2Fe2O5 structure transforms into an anion-deficient perovskite modulated by periodically spaced crystallographic shear (CS) planes. Considering the layered Pb2Fe2O5 structure as a parent matrix for the nucleation and growth of CS planes allows an explanation of the specific microstructure observed for the CS structures in the PbFeO system.
Address
Corporate Author				Thesis
Publisher		Place of Publication	Easton, Pa	Editor
Language		Wos	000290978400038	Publication Date	2011-04-29
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	16	Open Access
Notes				Approved	Most recent IF: 4.857; 2011 IF: 4.601
Call Number	UA @ lucian @ c:irua:90141			Serial	1809
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Author	Prituzhalov, V.A.; Ardashnikova, E.I.; Vinogradov, A.A.; Dolgikh, V.A.; Videau, J.-J.; Fargin, E.; Abakumov, A.M.; Tarakina, N.V.; Van Tendeloo, G.
Title	New anion-conducting solid solutions Bi_1-xTe_x(O,F)_2+\delta (x > 0.5) and glassceramic material on their base			Type	A1 Journal article
Year	2011	Publication	Journal of fluorine chemistry	Abbreviated Journal	J Fluorine Chem
Volume	132	Issue	12	Pages	1110-1116
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	The anion-excess fluorite-like solid solutions with general composition Bi1−xTex(O,F)2+δ (x > 0.5) have been synthesized by a solid state reaction of TeO2, BiF3 and Bi2O3 at 873 K with following quenching. The homogeneity areas and polymorphism of the I ↔ IV Bi1−xTex(O,F)2+δ phases were investigated. The crystal structure of the low temperature IV-Bi1−xTex(O,F)2+δ phase has been solved using electron diffraction and X-ray powder diffraction (a = 11.53051(9) Å, S.G. Ia-3, RI = 0.046, RP = 0.041). Glass formation area in the Bi2O3BiF3TeO2 (10% TiO2) system was investigated. IVBi1−xTex(O,F)2+δ phase starts to crystallize at short-time (0.53 h) annealing of oxyfluoride glasses at temperatures above Tg (600615 K). The ionic conductivity of the crystalline Bi1−xTex(O,F)2+δ phase and corresponding glass-ceramics was investigated. Activation energy of conductivity Ea = 0.41(2) eV for the IV-Bi1−xTex(O,F)2+δ crystalline samples and Ea = 0.73 eV for the glass-ceramic samples were obtained. Investigation of the oxyfluoride samples with a constant cation ratio demonstrates essential influence of excess fluorine anions on the ionic conductivity.
Address
Corporate Author				Thesis
Publisher		Place of Publication	Lausanne	Editor
Language		Wos	000296936300011	Publication Date	2011-07-07
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	0022-1139;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	2.101	Times cited	2	Open Access
Notes				Approved	Most recent IF: 2.101; 2011 IF: 2.033
Call Number	UA @ lucian @ c:irua:93687			Serial	2305
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Author	Tsirlin, A.A.; Nath, R.; Abakumov, A.M.; Furukawa, Y.; Johnston, D.C.; Hemmida, M.; Krug von Nidda, H.-A.; Loidl, A.; Geibel, C.; Rosner, H.
Title	Phase separation and frustrated square lattice magnetism of Na_1.5VOPO₄F_0.5			Type	A1 Journal article
Year	2011	Publication	Physical review : B : condensed matter and materials physics	Abbreviated Journal	Phys Rev B
Volume	84	Issue	1	Pages	014429-014429,16
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Crystal structure, electronic structure, and magnetic behavior of the spin-1/2 quantum magnet Na1.5VOPO4F0.5 are reported. The disorder of Na atoms leads to a sequence of structural phase transitions revealed by synchrotron x-ray powder diffraction and electron diffraction. The high-temperature second-order α↔β transition at 500 K is of the order-disorder type, whereas the low-temperature β↔γ+γ′ transition around 250 K is of the first order and leads to a phase separation toward the polymorphs with long-range (γ) and short-range (γ′) order of Na. Despite the complex structural changes, the magnetic behavior of Na1.5VOPO4F0.5 probed by magnetic susceptibility, heat capacity, and electron spin resonance measurements is well described by the regular frustrated square lattice model of the high-temperature α-polymorph. The averaged nearest-neighbor and next-nearest-neighbor couplings are J̅ 1≃−3.7 K and J̅ 2≃6.6 K, respectively. Nuclear magnetic resonance further reveals the long-range ordering at TN=2.6 K in low magnetic fields. Although the experimental data are consistent with the simplified square-lattice description, band structure calculations suggest that the ordering of Na atoms introduces a large number of inequivalent exchange couplings that split the square lattice into plaquettes. Additionally, the direct connection between the vanadium polyhedra induces an unusually strong interlayer coupling having effect on the transition entropy and the transition anomaly in the specific heat. Peculiar features of the low-temperature crystal structure and the relation to isostructural materials suggest Na1.5VOPO4F0.5 as a parent compound for the experimental study of tetramerized square lattices as well as frustrated square lattices with different values of spin.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000293247400008	Publication Date	2011-07-28
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	1098-0121;1550-235X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.836	Times cited	47	Open Access
Notes				Approved	Most recent IF: 3.836; 2011 IF: 3.691
Call Number	UA @ lucian @ c:irua:91770			Serial	2588
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Author	Kirsanova, M.A.; Reshetova, L.N.; Olenev, A.V.; Abakumov, A.M.; Shevelkov, A.V.
Title	Semiclathrates of the GePTe system : synthesis and crystal structures			Type	A1 Journal article
Year	2011	Publication	Chemistry: a European journal	Abbreviated Journal	Chem-Eur J
Volume	17	Issue	20	Pages	5719-5726
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Novel compounds [Ge46−xPx]Tey (13.9≤x≤15.6, 5.92≤y≤7.75) with clathrate-like structures have been prepared and structurally characterized. They crystallize in the space group Fmequation image with the unit cell parameter changing from 20.544(2) to 20.698(2) Å (Z=8) on going from x=13.9 to x=15.6. Their crystal structure is composed of a covalently bonded Ge[BOND]P framework that hosts tellurium atoms in the guest positions and can be viewed as a peculiar variant of the type I clathrate superstructure. In contrast to the conventional type I clathrates, [Ge46−xPx]Tey contain tricoordinated (3b) atoms and no vacancies in the framework positions. As a consequence of the transformation of the framework, the majority of the guest tellurium atoms form a single covalent bond with the host framework and thus the title compounds are the first representative of semiclathrates with covalent bonding. A comparison is made with silicon clathrates and the evolution of the crystal structure upon changing the tellurium content is discussed.
Address
Corporate Author				Thesis
Publisher		Place of Publication	Weinheim	Editor
Language		Wos	000290216000028	Publication Date	2011-04-05
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	0947-6539;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	5.317	Times cited	17	Open Access
Notes				Approved	Most recent IF: 5.317; 2011 IF: 5.925
Call Number	UA @ lucian @ c:irua:89773			Serial	2981
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Author	Hadermann, J.; Abakumov, A.M.; Turner, S.; Hafideddine, Z.; Khasanova, N.R.; Antipov, E.V.; Van Tendeloo, G.
Title	Solving the structure of Li ion battery materials with precession electron diffraction : application to Li₂CoPo₄F			Type	A1 Journal article
Year	2011	Publication	Chemistry of materials	Abbreviated Journal	Chem Mater
Volume	23	Issue	15	Pages	3540-3545
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	The crystal structure of the Li2CoPO4F high-voltage cathode for Li ion rechargeable batteries has been completely solved from precession electron diffraction (PED) data, including the location of the Li atoms. The crystal structure consists of infinite chains of CoO4F2 octahedra sharing common edges and linked into a 3D framework by PO4 tetrahedra. The chains and phosphate anions together delimit tunnels filled with the Li atoms. This investigation demonstrates that PED can be successfully applied for obtaining structural information on a variety of Li-containing electrode materials even from single micrometer-sized crystallites.
Address
Corporate Author				Thesis
Publisher		Place of Publication	Washington, D.C.	Editor
Language		Wos	000293357100019	Publication Date	2011-07-11
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	46	Open Access
Notes	Fwo; Bof			Approved	Most recent IF: 9.466; 2011 IF: 7.286
Call Number	UA @ lucian @ c:irua:90357			Serial	3053
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Author	Abakumov, A.M.; Tsirlin, A.A.; Perez-Mato, J.M.; Petřiček, V.; Rosner, H.; Yang, T.; Greenblatt, M.
Title	Spiral ground state against ferroelectricity in the frustrated magnet BiMnFe₂O₆			Type	A1 Journal article
Year	2011	Publication	Physical review : B : condensed matter and materials physics	Abbreviated Journal	Phys Rev B
Volume	83	Issue	21	Pages	214402-214402,10
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	The spiral magnetic structure and underlying spin lattice of BiMnFe2O6 are investigated by low-temperature neutron powder diffraction and density functional theory band structure calculations. In spite of the random distribution of the Mn3+ and Fe3+ cations, this centrosymmetric compound undergoes a transition into an incommensurate antiferromagnetically ordered state below TN≃220 K. The magnetic structure is characterized by the propagation vector k=[0,β,0] with β≃0.14 and the P221211′(0β0)0s0s magnetic superspace symmetry. It comprises antiferromagnetic helixes propagating along the b axis. The magnetic moments lie in the ac plane and rotate about π(1+β)≃204.8-deg angle between the adjacent magnetic atoms along b. The spiral magnetic structure arises from the peculiar frustrated arrangement of exchange couplings in the ab plane. The antiferromagnetic coupling along the c axis cancels the possible electric polarization and prevents ferroelectricity in BiMnFe2O6.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000291197400001	Publication Date	2011-06-03
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	1098-0121;1550-235X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.836	Times cited	12	Open Access
Notes				Approved	Most recent IF: 3.836; 2011 IF: 3.691
Call Number	UA @ lucian @ c:irua:90080			Serial	3107
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Author	Rusakov, D.; Abakumov, A.M.; Yamaura, K.; Belik, A.A.; Van Tendeloo, G.; Takayama-Muromachi, E.
Title	Structural evolution of the BiFeO₃-LaFeO₃ system			Type	A1 Journal article
Year	2011	Publication	Chemistry of materials	Abbreviated Journal	Chem Mater
Volume	23	Issue	2	Pages	285-292
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	The (1 − x)BiFeO3−xLaFeO3 system has been investigated and characterized by room-temperature and high-temperature laboratory and synchrotron powder X-ray diffraction, electron diffraction, high-resolution transmission electron microscopy, differential scanning calorimetry, and magnetization measurements. At room temperature, the ferroelectric R3c phase is observed for 0.0 ≤ x ≤ 0.10. The PbZrO3-related √2ap × 2√2ap × 4ap superstructure (where ap is the parameter of the cubic perovskite subcell) is observed for Bi0.82La0.18FeO3, while an incommensurately modulated phase is formed for 0.19 ≤ x ≤ 0.30 with the √2ap × 2ap × √2ap basic unit cell. The GdFeO3-type phase with space group Pnma (√2ap × 2ap × √2ap) is stable at 0.50 ≤ x ≤ 1. Bi0.82La0.18FeO3 has no detectable homogeneity range (space group Pnam, a = 5.6004(1) Å, b = 11.2493(3) Å, c = 15.6179(3) Å). The incommensurately modulated Bi0.75La0.25FeO3 structure was solved from synchrotron X-ray powder diffraction data (Imma(00γ)s00 superspace group, a = 5.5956(1) Å, b = 7.8171(1) Å, c = 5.62055(8) Å, q = 0.4855(4)c*, RP = 0.023, RwP = 0.033). In this structure, cooperative displacements of the Bi and O atoms occur, which order within the (AO) (where A = Bi, La) layers, resulting in an antipolar structure. Local fluctuations of the intralayer antipolar ordering are compensated by an interaction with the neighboring (AO) layers. A coupling of the antipolar displacements with the cooperative tilting distortion of the perovskite octahedral framework is proposed as the origin of the incommensurability. All the phases transform to the GdFeO3-type structure at high temperatures. Bi0.82La0.18FeO3 shows an intermediate PbZrO3-type phase with √2ap × 2√2ap × 2ap (space group Pbam; a = 5.6154(2) Å, b = 11.2710(4) Å, and c = 7.8248(2) Å at 570 K). The compounds in the compositional range of 0.18 ≤ x ≤ 0.95 are canted antiferromagnets.
Address
Corporate Author				Thesis
Publisher		Place of Publication	Washington, D.C.	Editor
Language		Wos	000286160800021	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	133	Open Access
Notes				Approved	Most recent IF: 9.466; 2011 IF: 7.286
Call Number	UA @ lucian @ c:irua:88650			Serial	3236
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Author	Korneychik, O.E.; Batuk, M.; Abakumov, A.M.; Hadermann, J.; Rozova, M.G.; Sheptyakov, D.V.; Pokholok, K.V.; Filimonov, D.S.; Antipov, E.V.
Title	Pb_2.85Ba_2.15Fe₄SnO₁₃ : a new member of the A_nB_nO_3n-2 anion-deficient perovskite-based homologous series			Type	A1 Journal article
Year	2011	Publication	Journal of solid state chemistry	Abbreviated Journal	J Solid State Chem
Volume	184	Issue	12	Pages	3150-3157
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Pb2.85Ba2.15Fe4SnO13, a new n=5 member of the anion-deficient perovskite based AnBnO3n−2 (A=Pb, Ba, B=Fe, Sn) homologous series, was synthesized by the solid state method. The crystal structure of Pb2.85Ba2.15Fe4SnO13 was investigated using a combination of neutron powder diffraction, electron diffraction, high angle annular dark field scanning transmission electron microscopy and Mössbauer spectroscopy. It crystallizes in the Ammm space group with unit cell parameters a=5.7990(1) Å, b=4.04293(7) Å and c=26.9561(5) Å. The Pb2.85Ba2.15Fe4SnO13 structure consists of quasi two-dimensional perovskite blocks separated by 1/2[110](1̄01)p crystallographic shear (CS) planes. The corner-sharing FeO6 octahedra at the CS planes are transformed into edge-sharing FeO5 distorted tetragonal pyramids. The octahedral positions in the perovskite blocks between the CS planes are jointly taken up by Fe and Sn, with a preference of Sn towards the position at the center of the perovskite block. The chains of FeO5 pyramids and (Fe,Sn)O6 octahedra of the perovskite blocks delimit six-sided tunnels at the CS planes occupied by double chains of Pb atoms. The compound is antiferromagnetically ordered below TN=368±15 K.
Address
Corporate Author				Thesis
Publisher		Place of Publication	London	Editor
Language		Wos	000297662500003	Publication Date	2011-09-30
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	7	Open Access
Notes				Approved	Most recent IF: 2.299; 2011 IF: 2.159
Call Number	UA @ lucian @ c:irua:94013			Serial	3550
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Author	Kazakov, S.M.; Abakumov, A.M.; Perz-Mato, J.M.; Ovchinnikov, A.V.; Roslova, M.V.; Boltalin, A.I.; Morozov, I.V.; Antipov, E.V.; Van Tendeloo, G.
Title	Uniform patterns of Fe-vacancy ordering in the K_x(Fe,Co)_2-ySe₂ superconductors			Type	A1 Journal article
Year	2011	Publication	Chemistry of materials	Abbreviated Journal	Chem Mater
Volume	23	Issue	19	Pages	4311-4316
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	The Fe-vacancy ordering patterns in the superconducting KxFe2ySe2 and nonsuperconducting Kx(Fe,Co)2ySe2 samples have been investigated by electron diffraction and high angle annular dark field scanning transmission electron microscopy. The Fe-vacancy ordering occurs in the ab plane of the parent ThCr2Si2-type structure, demonstrating two types of patterns. Superstructure I retains the tetragonal symmetry and can be described with the aI = bI = as√5 (as is the unit cell parameter of the parent ThCr2Si2-type structure) supercell and I4/m space group. Superstructure II reduces the symmetry to orthorhombic with the aII = as√2, bII = 2as√2 supercell and the Ibam space group. This type of superstructure is observed for the first time in KxFe2ySe2. The Fe-vacancy ordering is inhomogeneous: the disordered areas interleave with the superstructures I and II in the same crystallite. The observed superstructures represent the compositionally dependent uniform ordering patterns of two species (the Fe atoms and vacancies) on a square lattice. More complex uniform ordered configurations, including compositional stripes, can be predicted for different chemical compositions of the KxFe2ySe2 (0 < y < 0.5) solid solutions.
Address
Corporate Author				Thesis
Publisher		Place of Publication	Washington, D.C.	Editor
Language		Wos	000295487800005	Publication Date	2011-09-13
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	20	Open Access
Notes				Approved	Most recent IF: 9.466; 2011 IF: 7.286
Call Number	UA @ lucian @ c:irua:92805			Serial	3810
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Author	Marikutsa, A.; Krivetskiy, V.; Yashina, L.; Rumyantseva, M.; Konstantinova, E.; Ponzoni, A.; Comini, E.; Abakumov, A.; Gaskov, A.
Title	Catalytic impact of RuOx clusters to high ammonia sensitivity of tin dioxide			Type	A1 Journal article
Year	2012	Publication	Sensors and actuators : B : chemical T2 – 25th Eurosensors Conference, SEP 04-07, 2011, Athens, GREECE	Abbreviated Journal	Sensor Actuat B-Chem
Volume	175	Issue		Pages	186-193
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	A comparative study of NH3-sensing performance of blank and modified nanocrystal line SnO2 was performed. Tin dioxide modified by ruthenium displayed the highest ammonia sensitivity with a maximum signal at 200 degrees C. The modifier was shown by XPS and EPR to occur in a mixed valence state of oxidized ruthenium distributed between the surface and bulk of tin dioxide nanocrystals. RuOx clustering on SnO2 surface was detected by means of electron microscopy assisted EDX-mapping. The effect of RuOx on tin dioxide interaction with ammonia was studied by temperature-programmed NH3 desorption, simultaneous Kelvin probe and DC-resistance measurements, EPR spectroscopy and analyses of the gas-solid interaction products. The modifier was shown to promote the materials reactivity to NH3 due to the catalytic activity of RuOx. The interaction with ammonia resulted in dipoles formation on the oxide surface along with reducing the grains net surface charge, established from the electron affinity increase and resistance decrease during NH3 exposure. The RuOx-catalyzed gas-solid interaction was deduced to proceed deeper than in the case of non-modified SnO2 and to yield nitrogen oxides (e.g. NO2), as was suggested by the oxidative character of gaseous products of NH3 interaction with RuOx-modified tin dioxide at 200 degrees C. (C) 2012 Elsevier B.V. All rights reserved.
Address
Corporate Author				Thesis
Publisher		Place of Publication	Lausanne	Editor
Language		Wos	000312358700033	Publication Date	2012-06-19
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	20	Open Access
Notes				Approved	Most recent IF: 5.401; 2012 IF: 3.535
Call Number	UA @ lucian @ c:irua:105985			Serial	293
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Author	Hadermann, J.; Abakumov, A.; Van Rompaey, S.; Perkisas, T.; Filinchuk, Y.; Van Tendeloo, G.
Title	Crystal structure of a lightweight borohydride from submicrometer crystallites by precession electron diffraction			Type	A1 Journal article
Year	2012	Publication	Chemistry of materials	Abbreviated Journal	Chem Mater
Volume	24	Issue	17	Pages	3401-3405
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	We demonstrate that precession electron diffraction at low-dose conditions can be successfully applied for structure analysis of extremely electron-beam-sensitive materials. Using LiBH4 as a test material, complete structural information, including the location of the H atoms, was obtained from submicrometer-sized crystallites. This demonstrates for the first time that, where conventional transmission electron microscopy techniques fail, quantitative precession electron diffraction can provide structural information from submicrometer particles of such extremely electron-beam-sensitive materials as complex lightweight hydrides. We expect the precession electron diffraction technique to be a useful tool for nanoscale investigations of thermally unstable lightweight hydrogen-storage materials.
Address
Corporate Author				Thesis
Publisher		Place of Publication	Washington, D.C.	Editor
Language		Wos	000308833400012	Publication Date	2012-08-01
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	17	Open Access
Notes				Approved	Most recent IF: 9.466; 2012 IF: 8.238
Call Number	UA @ lucian @ c:irua:101845			Serial	567
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Author	Bourgeois, J.; Hervieu, M.; Poienar, M.; Abakumov, A.M.; Elkaïm, E.; Sougrati, M.T.; Porcher, F.; Damay, F.; Rouquette, J.; Van Tendeloo, G.; Maignan, A.; Haines, J.; Martin, C.;
Title	Evidence of oxygen-dependent modulation in LuFe₂O₄			Type	A1 Journal article
Year	2012	Publication	Physical review : B : condensed matter and materials physics	Abbreviated Journal	Phys Rev B
Volume	85	Issue	6	Pages	064102-064120,10
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	A polycrystalline sample of LuFe2O4 has been investigated by means of powder synchrotron x-ray and neutron diffraction and transmission electron microscopy (TEM), along with Mössbauer spectroscopy and transport and magnetic properties. A monoclinic distortion is unambiguously evidenced, and the crystal structure is refined in the monoclinic C2/m space group [aM = 5.9563(1) Å, bM = 3.4372(1) Å, cM = 8.6431(1) Å, β = 103.24(1)°]. Along with the previously reported modulations distinctive of the charge-ordering (CO) of the iron species, a new type of incommensurate order is observed, characterized by a vector q⃗1 = α1a⃗M* + γ1c⃗M* (with α1 ≅ 0.55, γ1 ≅ 0.13). In situ heating TEM observations from 300 to 773 K confirm that the satellites associated with q⃗1 vanish completely, only at a temperature significantly higher than the CO temperature. This incommensurate modulation has a displacive character and corresponds primarily to a transverse displacive modulation wave of the Lu cations position, as revealed by the high resolution, high angle annular dark field scanning TEM images and in agreement with synchrotron data refinements. Analyses of vacuum-annealed samples converge toward the hypothesis of a new ordering mechanism, associated with a tiny oxygen deviation from the O4 stoichiometry.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000299896900003	Publication Date	2012-02-06
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	1098-0121;1550-235X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.836	Times cited	24	Open Access
Notes	Hercules			Approved	Most recent IF: 3.836; 2012 IF: 3.767
Call Number	UA @ lucian @ c:irua:95042			Serial	1095
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Author	Hadermann, J.; Abakumov, A.M.; Tsirlin, A.A.; Rozova, M.G.; Sarakinou, E.; Antipov, E.V.
Title	Expanding the Ruddlesden-Popper manganite family : the n=3 La_3.2Ba_0.8Mn₃O₁₀ Member			Type	A1 Journal article
Year	2012	Publication	Inorganic chemistry	Abbreviated Journal	Inorg Chem
Volume	51	Issue	21	Pages	11487-11492
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	La3.2Ba0.8Mn3O10, a representative of the rare n = 3 members of the Ruddlesden-Popper manganites A(n+1)Mn(n)O(3n+1), was synthesized in an evacuated sealed silica tube. Its crystal structure was refined from a combination of powder X-ray diffraction (PXD) and precession electron diffraction (PED) data, with the rotations of the MnO6 octahedra described within the symmetry-adapted mode approach (space group Cccm, a = 29.068(1) angstrom, b = 5.5504(5) angstrom, c = 5.5412(5) angstrom; PXD RF = 0.053, RP = 0.026; PED RF = 0.248). The perovskite block in La3.2Ba0.8Mn3O10 features an octahedral tilting distortion with out-of-phase rotations of the Mn06 octahedra according to the (Phi,Phi,0)(Phi,Phi,0) mode, observed for the first time in the n = 3 Ruddlesden-Popper structures. The Mn06 octahedra demonstrate a noticeable deformation with the elongation of two apical Mn-O bonds due to the Jahn-Teller effect in the Mn3+ cations. The relationships between the octahedral tilting distortion, the ionic radii of the cations at the A- and B-positions, and the mismatch between the perovslcite and rock-salt blocks of the Ruddlesden-Popper structure are discussed. At low temperatures, La3.2Ba0.8Mn3O10 reveals a sizable remnant magnetization of about 1.3 mu(B)/Mn at 2K, and shows signatures of spin freezing below 150 K.
Address
Corporate Author				Thesis
Publisher		Place of Publication	Easton, Pa	Editor
Language		Wos	000313220200036	Publication Date	2012-10-17
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	2	Open Access
Notes				Approved	Most recent IF: 4.857; 2012 IF: 4.593
Call Number	UA @ lucian @ c:irua:110121			Serial	1133
Permanent link to this record



Author	Dubrovinsky, L.; Dubrovinskaia, N.; Prakapenka, V.B.; Abakumov, A.M.
Title	Implementation of micro-ball nanodiamond anvils for high-pressure studies above 6 Mbar			Type	A1 Journal article
Year	2012	Publication	Nature communications	Abbreviated Journal	Nat Commun
Volume	3	Issue		Pages	1163-1167
Keywords	A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract	Since invention of the diamond anvil cell technique in the late 1950s for studying materials at extreme conditions, the maximum static pressure generated so far at room temperature was reported to be about 400 GPa. Here we show that use of micro-semi-balls made of nanodiamond as second-stage anvils in conventional diamond anvil cells drastically extends the achievable pressure range in static compression experiments to above 600 GPa. Micro-anvils (10-50 mu m in diameter) of superhard nano-diamond (with a grain size below similar to 50 nm) were synthesized in a large volume press using a newly developed technique. In our pilot experiments on rhenium and gold we have studied the equation of state of rhenium at pressures up to 640 GPa and demonstrated the feasibility and crucial necessity of the in situ ultra high-pressure measurements for accurate determination of material properties at extreme conditions.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000313514100073	Publication Date	2012-10-23
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	2041-1723;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	12.124	Times cited	150	Open Access
Notes				Approved	Most recent IF: 12.124; 2012 IF: 10.015
Call Number	UA @ lucian @ c:irua:110134			Serial	1563
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Author	Dachraoui, W.; Hadermann, J.; Abakumov, A.M.; Tsirlin, A.A.; Batuk, D.; Glazyrin, K.; McCammon, C.; Dubrovinsky, L.; Van Tendeloo, G.
Title	Local oxygen-vacancy ordering and twinned octahedral tilting pattern in the Bi_0.81Pb_0.19FeO_2.905 cubic perovskite			Type	A1 Journal article
Year	2012	Publication	Chemistry of materials	Abbreviated Journal	Chem Mater
Volume	24	Issue	7	Pages	1378-1385
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	The structure of Bi0.81Pb0.19FeO2.905 was investigated on different length scales using a combination of electron diffraction, high-resolution scanning transmission electron microscopy, synchrotron X-ray powder diffraction, and Mössbauer spectroscopy. In the 80300 K temperature range, the average crystal structure of Bi0.81Pb0.19FeO2.905 is a cubic Pm3̅m perovskite with a = 3.95368(3) Å at T = 300 K. The (Pb2+, Bi3+) cations and O2 anions are randomly displaced along the 110 cubic directions, indicating the steric activity of the lone pair on the Pb2+ and Bi3+ cations and a tilting distortion of the perovskite framework. The charge imbalance induced by the heterovalent Bi3+ → Pb2+ substitution is compensated by the formation of oxygen vacancies preserving the trivalent state of the Fe cations. On a short scale, oxygen vacancies are located in anion-deficient (FeO1.25) layers that are approximately 6 perovskite unit cells apart and transform every sixth layer of the FeO6 octahedra into a layer with a 1:1 mixture of corner-sharing FeO4 tetrahedra and FeO5 tetragonal pyramids. The anion-deficient layers act as twin planes for the octahedral tilting pattern of adjacent perovskite blocks. They effectively randomize the octahedral tilting and prevent the cooperative distortion of the perovskite framework. The disorder in the anion sublattice impedes cooperative interactions of the local dipoles induced by the off-center displacements of the Pb and Bi cations. Magnetic susceptibility measurements evidence the antiferromagnetic ordering in Bi0.81Pb0.19FeO2.905 at low temperatures.
Address
Corporate Author				Thesis
Publisher		Place of Publication	Washington, D.C.	Editor
Language		Wos	000302487500018	Publication Date	2012-03-13
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	27	Open Access
Notes				Approved	Most recent IF: 9.466; 2012 IF: 8.238
Call Number	UA @ lucian @ c:irua:97389			Serial	1829
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Author	Tan, H.; Verbeeck, J.; Abakumov, A.; Van Tendeloo, G.
Title	Oxidation state and chemical shift investigation in transition metal oxides by EELS			Type	A1 Journal article
Year	2012	Publication	Ultramicroscopy	Abbreviated Journal	Ultramicroscopy
Volume	116	Issue		Pages	24-33
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Transition metal L2,3 electron energy-loss spectra for a wide range of V-, Mn- and Fe-based oxides were recorded and carefully analyzed for their correlation with the formal oxidation states of the transition metal ions. Special attention is paid to obtain an accurate energy scale which provides absolute energy positions for all core-loss edges. The white-line ratio method, chemical shift method, ELNES fitting method, two-parameter method and other methods are compared and their validity is discussed. Both the ELNES fitting method and the chemical shift method have the advantage of a wide application range and good consistency but require special attention to accurately measure the core-loss edge position. The obtained conclusions are of fundamental importance, e.g., for obtaining atomic resolution oxidation state information in modern experiments.
Address
Corporate Author				Thesis
Publisher		Place of Publication	Amsterdam	Editor
Language		Wos	000304473700004	Publication Date	2012-03-10
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	0304-3991;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	2.843	Times cited	413	Open Access
Notes	Fwo			Approved	Most recent IF: 2.843; 2012 IF: 2.470
Call Number	UA @ lucian @ c:irua:96959UA @ admin @ c:irua:96959			Serial	2541
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Author	Frolov, D.D.; Kotovshchikov, Y.N.; Morozov, I.V.; Boltalin, A.I.; Fedorova, A.A.; Marikutsa, A.V.; Rumyantseva, M.N.; Gaskov, A.M.; Sadovskaya, E.M.; Abakumov, A.M.
Title	Oxygen exchange on nanocrystalline tin dioxide modified by palladium			Type	A1 Journal article
Year	2012	Publication	Journal of solid state chemistry	Abbreviated Journal	J Solid State Chem
Volume	186	Issue		Pages	1-8
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Temperature-programmed oxygen isotopic exchange study was performed on nanocrystalline tin dioxide-based materials synthesized via sol-gel route and modified by palladium. Such materials are widely used as resistive gas sensors. The experiments were carried out in a flow-reactor up to complete isotopic substitution of oxygen. Substantial rates of isotopic exchange for SnO2 were observed from about 700 K. The distribution of isotopic molecules O-16(2). (OO)-O-16-O-18 and O-18(2) corresponds to simple dioxygen heteroexchange mechanism with single lattice oxygen atom. The modification of SnO2 by Pd introduced multiple heteroexchange mechanism with preliminary O-2 dissociation on the clusters surface. Spill-over of atomic oxygen from Pd to the surface of SnO2 and fast exchange with lattice oxygen result in more than 100% increase of apparent heteroexchange rate. The exchange on SnO2/Pd was shown to be a complex process involving partial deactivation of the catalytic centers at temperature higher than 750 K. (C) 2011 Elsevier Inc. All rights reserved.
Address
Corporate Author				Thesis
Publisher		Place of Publication	London	Editor
Language		Wos	000299801400001	Publication Date	2011-12-08
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	34	Open Access
Notes				Approved	Most recent IF: 2.299; 2012 IF: 2.040
Call Number	UA @ lucian @ c:irua:96202			Serial	2546
Permanent link to this record



Author	Tytgat, T.; Hauchecorne, B.; Abakumov, A.M.; Smits, M.; Verbruggen, S.W.; Lenaerts, S.
Title	Photocatalytic process optimisation for ethylene oxidation			Type	A1 Journal article
Year	2012	Publication	Chemical engineering journal	Abbreviated Journal	Chem Eng J
Volume	209	Issue		Pages	494-500
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Sustainable Energy, Air and Water Technology (DuEL)
Abstract	When studying photocatalysis it is important to consider, beside the chemical approach, the engineering part related to process optimisation. To achieve this a fixed bed photocatalytic set-up consisting of different catalyst placings, in order to vary catalyst distribution, is studied. The use of a fixed quantity of catalyst placed packed or randomly distributed in the reactor, results in an almost double degradation for the distributed catalyst. Applying this knowledge leads to an improved performance with limited use of catalyst. A reactor only half filled with catalyst leads to higher degradation performance compared to a completely filled reactor. Taking into account this simple process optimisation by better distributing the catalyst a more sustainable photocatalytic air purification process is achieved. (C) 2012 Elsevier B.V. All rights reserved.
Address
Corporate Author				Thesis
Publisher		Place of Publication	Lausanne	Editor
Language		Wos	000311190500058	Publication Date	2012-08-22
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	1385-8947;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	6.216	Times cited	12	Open Access
Notes	; We are grateful for the delivered photocatalyst by Evonik as well as for the PhD grant (T. Tytgat) given by the Institute of Innovation by Science and Technology in Flanders (IWT). ;			Approved	Most recent IF: 6.216; 2012 IF: 3.473
Call Number	UA @ lucian @ c:irua:105185			Serial	2609
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Author	Li, M.R.; Adem, U.; McMitchell, S.R.C.; Xu, Z.; Thomas, C.I.; Warren, J.E.; Giap, D.V.; Niu, H.; Wan, X.; Palgrave, R.G.; Schiffmann, F.; Cora, F.; Slater, B.; Burnett, T.L.; Cain, M.G.; Abakumov, A.M.; Van Tendeloo, G.; Thomas, M.F.; Rosseinsky, M.J.; Claridge, J.B.;
Title	A polar corundum oxide displaying weak ferromagnetism at room temperature			Type	A1 Journal article
Year	2012	Publication	Journal of the American Chemical Society	Abbreviated Journal	J Am Chem Soc
Volume	134	Issue	8	Pages	3737-3747
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Combining long-range magnetic order with polarity in the same structure is a prerequisite for the design of (magnetoelectric) multiferroic materials. There are now several demonstrated strategies to achieve this goal, but retaining magnetic order above room temperature remains a difficult target. Iron oxides in the +3 oxidation state have high magnetic ordering temperatures due to the size of the coupled moments. Here we prepare and characterize ScFeO3 (SFO), which under pressure and in strain-stabilized thin films adopts a polar variant of the corundum structure, one of the archetypal binary oxide structures. Polar corundum ScFeO3 has a weak ferromagnetic ground state below 356 K-this is in contrast to the purely antiferromagnetic ground state adopted by the well-studied ferroelectric BiFeO3.
Address
Corporate Author				Thesis
Publisher		Place of Publication	Washington, D.C.	Editor
Language		Wos	000301161600027	Publication Date	2012-01-23
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	48	Open Access
Notes				Approved	Most recent IF: 13.858; 2012 IF: 10.677
Call Number	UA @ lucian @ c:irua:97200			Serial	2658
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Author	Tsirlin, A.A.; Abakumov, A.M.; Ritter, C.; Henry, P.F.; Janson, O.; Rosner, H.
Title	Short-range order of Br and three-dimensional magnetism in (CuBr)LaNb₂O₇			Type	A1 Journal article
Year	2012	Publication	Physical review : B : condensed matter and materials physics	Abbreviated Journal	Phys Rev B
Volume	85	Issue	21	Pages	214427
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	We present a comprehensive study of the crystal structure, magnetic structure, and microscopic magnetic model of (CuBr)LaNb2O7, the Br analog of the spin-gap quantum magnet (CuCl) LaNb2O7. Despite similar crystal structures and spin lattices, the magnetic behavior and even peculiarities of the atomic arrangement in the Cl and Br compounds are very different. The high- resolution x-ray and neutron data reveal a split position of Br atoms in (CuBr) LaNb2O7. This splitting originates from two possible configurations developed by [CuBr] zigzag ribbons. While the Br atoms are locally ordered in the ab plane, their arrangement along the c direction remains partially disordered. The predominant and energetically more favorable configuration features an additional doubling of the c lattice parameter that was not observed in (CuCl) LaNb2O7. (CuBr) LaNb2O7 undergoes long-range antiferromagnetic ordering at T-N = 32 K, which is nearly 70% of the leading exchange coupling J4 similar or equal to 48 K. The Br compound does not show any experimental signatures of low-dimensional magnetism because the underlying spin lattice is three-dimensional. The coupling along the c direction is comparable to the couplings in the ab plane, even though the shortest Cu-Cu distance along c (11.69 angstrom) is three times larger than nearest-neighbor distances in the ab plane (3.55 angstrom). The stripe antiferromagnetic long-range order featuring columns of parallel spins in the ab plane and antiparallel spins along c is verified experimentally and confirmed by the microscopic analysis.
Address
Corporate Author				Thesis
Publisher		Place of Publication		Editor
Language		Wos	000305557600002	Publication Date	2012-06-22
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	1098-0121;1550-235X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.836	Times cited	5	Open Access
Notes				Approved	Most recent IF: 3.836; 2012 IF: 3.767
Call Number	UA @ lucian @ c:irua:100289			Serial	2998
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Author	Turner, S.; Egoavil, R.; Batuk, M.; Abakumov, A.A.; Hadermann, J.; Verbeeck, J.; Van Tendeloo, G.
Title	Site-specific mapping of transition metal oxygen coordination in complex oxides			Type	A1 Journal article
Year	2012	Publication	Applied physics letters	Abbreviated Journal	Appl Phys Lett
Volume	101	Issue	24	Pages	241910
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	We demonstrate site-specific mapping of the oxygen coordination number for transition metals in complex oxides using atomically resolved electron energy-loss spectroscopy in an aberration-corrected scanning transmission electron microscope. Pb2Sr2Bi2Fe6O16 contains iron with a constant Fe3+ valency in both octahedral and tetragonal pyramidal coordination and is selected to demonstrate the principle of site-specific coordination mapping. Analysis of the site-specific Fe-L2,3 data reveals distinct variations in the fine structure that are attributed to Fe in a six-fold (octahedron) or five-fold (distorted tetragonal pyramid) oxygen coordination. Using these variations, atomic resolution coordination maps are generated that are in excellent agreement with simulations.
Address
Corporate Author				Thesis
Publisher	American Institute of Physics	Place of Publication	New York, N.Y.	Editor
Language		Wos	000312490000035	Publication Date	2012-12-12
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	0003-6951;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	3.411	Times cited	12	Open Access
Notes	Fwo; Countatoms; Vortex; Esteem 312483; esteem2jra3 ECASJO;			Approved	Most recent IF: 3.411; 2012 IF: 3.794
Call Number	UA @ lucian @ c:irua:105302UA @ admin @ c:irua:105302			Serial	3030
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Author	Gardner, G.P.; Go, Y.B.; Robinson, D.M.; Smith, P.F.; Hadermann, J.; Abakumov, A.; Greenblatt, M.; Dismukes, G.C.
Title	Structural requirements in lithium cobalt oxides for the catalytic oxidation of water			Type	A1 Journal article
Year	2012	Publication	Angewandte Chemie: international edition in English	Abbreviated Journal	Angew Chem Int Edit
Volume	51	Issue	7	Pages	1616-1619
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract
Address
Corporate Author				Thesis
Publisher		Place of Publication	Weinheim	Editor
Language		Wos	000299946400020	Publication Date	2012-01-11
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	1433-7851;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	11.994	Times cited	119	Open Access
Notes				Approved	Most recent IF: 11.994; 2012 IF: 13.734
Call Number	UA @ lucian @ c:irua:99173			Serial	3258
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Author	Napolsky, P.S.; Drozhzhin, O.A.; Istomin, S.Y.; Kazakov, S.M.; Antipov, E.V.; Galeeva, A.V.; Gippius, A.A.; Svensson, G.; Abakumov, A.M.; Van Tendeloo, G.
Title	Structure and high-temperature properties of the (Sr,Ca,Y)(Co,Mn)O_3-y perovskites – perspective cathode materials for IT-SOFC			Type	A1 Journal article
Year	2012	Publication	Journal of solid state chemistry	Abbreviated Journal	J Solid State Chem
Volume	192	Issue		Pages	186-194
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Oxygen deficient perovskites Sr0.75Y0.25Co1-xMnxO3-y, x=0.5 and 0.75, were prepared by using the citrate route at 1373-1573 K for 48 h. The cubic Pm-3m perovskite structure for x=0.5 was confirmed by electron diffraction study and refined using neutron powder diffraction (NPD) data. For x=0.75, the superstructure corresponding to a=root 2 x a(per), b=2 x a(per), c=root 2 x a(per) (a(0)b(-)b(-) tilt system, space group Imma) was revealed by electron diffraction. The solid solution Sr0.75-xCaxY0.25Co0.25Mn0.75O3-y, 0.1 <= x <= 0.6 and compound Ca0.75Y0.25Mn0.85Co0.15O2.92 were prepared in air at 1573 K for 48 h. The crystal structure of Ca0.75Y0.25Mn0.85Co0.15O2.92 was refined using NPD data (S.G. Pnma, a=5.36595(4), b=7.5091(6), c=5.2992(4) angstrom, R-p=0.057, R-wp=0.056, chi(2)=4.26). High-temperature thermal expansion properties of the prepared compounds were studied in air using both dilatometry and high-temperature X-ray powder diffraction data (HTXRPD). They expanding non-linearly at 298-1073 K due to the loss of oxygen at high temperatures. Calculated average thermal expansion coefficients (TECs) for Sr0.75Y0.25Co1-xMnxO3-y, x=0.5, 0.75 and Ca0.75Y0.25Mn0.85Co0.15O2.92(1) are 15.5, 15.1, and 13.8 ppm K-1, respectively. Anisotropy of the thermal expansion along different unit cell axes was observed for Sr0.15Ca0.6Y0.25Co0.25Mn0.75O3-y, and Ca0.75Y0.25Mn0.85Co0.15O2.92. Conductivity of Sr0.75Y0.25Co1-xMnxO3-y, x=0.5 and 0.75 increases with the temperature reaching 110 S/cm for x=0.5 and 44 S/cm for x=0.75 at 1173 K. Samples of Sr0.75-xCaxY0.25Co0.25Mn0.75O3-y, 0.1 <= y <= 0.6 were found to be n-type conductors at room temperature with the similar temperature dependence of the conductivity and demonstrated the increase of the sigma value from similar to 1 to similar to 50 S/cm as the temperature increases from 300 to 1173 K. Their conductivity is described in terms of the small polaron charge transport with the activation energy (E-p) increasing from 340 to 430 meV with an increase of the calcium content from x=0 to x=0.6. (C) 2012 Elsevier Inc. All rights reserved.
Address
Corporate Author				Thesis
Publisher		Place of Publication	London	Editor
Language		Wos	000307028300030	Publication Date	2012-03-31
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	5	Open Access
Notes				Approved	Most recent IF: 2.299; 2012 IF: 2.040
Call Number	UA @ lucian @ c:irua:101119			Serial	3279
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Author	Charkin, D.O.; Urmanov, A.V.; Kazakov, S.M.; Batuk, D.; Abakumov, A.M.; Knöner, S.; Gati, E.; Wolf, B.; Lang, M.; Shevelkov, A.V.; Van Tendeloo, G.; Antipov, E.V.;
Title	Synthesis, crystal structure, transport, and magnetic properties of novel ternary copper phosphides, A₂Cu₆P₅(A = Sr, Eu) and EuCu₄P₃			Type	A1 Journal article
Year	2012	Publication	Inorganic chemistry	Abbreviated Journal	Inorg Chem
Volume	51	Issue	16	Pages	8948-8955
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	Three new ternary copper phosphides, Sr2Cu6P5, Eu2Cu6P5, and EuCu4P3, have been synthesized from the elements in evacuated silica capsules. Eu2Cu6P5 and Sr2Cu6P5 adopt the Ca2Cu6P5-type structure, while EuCu4P3 is isostructural to BaMg4Si3 and still remains the only representative of this structure type among the ternary Cu pnictides. All three materials show metallic conductivity in the temperature range 2 K <= T <= 290 K, with no indication for superconductivity. For Eu2Cu6P5 and EuCu4P3, long-range magnetic order was observed, governed by 4f local moments on the Eu atoms with predominant ferromagnetic interactions. While Eu2Cu6P5 shows a single ferromagnetic transition at T-C = 34 K, the magnetic behavior of EuCu4P3 is more complex, giving rise to three consecutive magnetic phase transitions at 70, 43, and 18 K.
Address
Corporate Author				Thesis
Publisher		Place of Publication	Easton, Pa	Editor
Language		Wos	000307606200042	Publication Date	2012-07-31
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	13	Open Access
Notes				Approved	Most recent IF: 4.857; 2012 IF: 4.593
Call Number	UA @ lucian @ c:irua:102217			Serial	3453
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Author	Pachoud, E.; Bréard, Y.; Martin, C.; Maignan, A.; Abakumov, A.M.; Suard, E.; Smith, R.I.; Suchomel, M.R.
Title	Bi_0.75Sr_0.25FeO_3-\delta : revealing order/disorder phenomena by combining diffraction techniques			Type	A1 Journal article
Year	2012	Publication	Solid state communications	Abbreviated Journal	Solid State Commun
Volume	152	Issue	5	Pages	331-336
Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract	The local and long range structure of polycrystalline samples of Bi0.75Sr0.25FeO3-delta has been probed by neutron and synchrotron X-ray diffraction coupled with transmission electron microscopy. It is found that the long range structure on average can be described by the cubic space group Pm-3m (a(p) congruent to 3.951 angstrom). However, the refinements revealed large atomic displacements for the (Bi, Sr) cations and the oxygen atoms from their ideal positions. The electron microscopy study indicates the existence of local phenomena like local ordering of oxygen vacancies, which are segregated at the randomly spaced parallel (FeO2-delta) planes, or the existence of region of different symmetry, probably R3c. At room temperature, the compound exhibits G-type antiferromagnetism (T-N congruent to 650 K) with a magnetic moment of congruent to 3.7 mu(B). (C) 2012 Elsevier Ltd. All rights reserved.
Address
Corporate Author				Thesis
Publisher		Place of Publication	New York, N.Y.	Editor
Language		Wos	000301329200001	Publication Date	2011-12-19
Series Editor		Series Title		Abbreviated Series Title
Series Volume		Series Issue		Edition
ISSN	0038-1098;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
Impact Factor	1.554	Times cited	6	Open Access
Notes				Approved	Most recent IF: 1.554; 2012 IF: 1.534
Call Number	UA @ lucian @ c:irua:97820			Serial	3516
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