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Sanchez-Barriga, J.; Aguilera, I.; Yashina, L., V; Tsukanova, D.Y.; Freyse, F.; Chaika, A.N.; Callaert, C.; Abakumov, A.M.; Hadermann, J.; Varykhalov, A.; Rienks, E.D.L.; Bihlmayer, G.; Blugel, S.; Rader, O. |
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Title |
Anomalous behavior of the electronic structure of (Bi1-xInx)2Se3across the quantum phase transition from topological to trivial insulator |
Type |
A1 Journal article |
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Year |
2018 |
Publication |
Physical review B |
Abbreviated Journal |
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Volume |
98 |
Issue |
23 |
Pages |
235110 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Using spin- and angle-resolved photoemission spectroscopy and relativistic many-body calculations, we investigate the evolution of the electronic structure of (Bi1-xInx)(2)Se-3)(2)Se-3 bulk single crystals around the critical point of the trivial to topological insulator quantum-phase transition. By increasing x, we observe how a surface gap opens at the Dirac point of the initially gapless topological surface state of Bi2Se3, leading to the existence of massive fermions. The surface gap monotonically increases for a wide range of x values across the topological and trivial sides of the quantum-phase transition. By means of photon-energy-dependent measurements, we demonstrate that the gapped surface state survives the inversion of the bulk bands which occurs at a critical point near x = 0.055. The surface state exhibits a nonzero in-plane spin polarization which decays exponentially with increasing x, and which persists in both the topological and trivial insulator phases. Our calculations reveal qualitative agreement with the experimental results all across the quantum-phase transition upon the systematic variation of the spin-orbit coupling strength. A non-time-reversal symmetry-breaking mechanism of bulk-mediated scattering processes that increase with decreasing spin-orbit coupling strength is proposed as explanation. |
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Wos |
000452322800003 |
Publication Date |
2018-12-05 |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2469-9969; 2469-9950 |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
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no |
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Call Number |
UA @ admin @ c:irua:156240 |
Serial |
7462 |
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Permanent link to this record |
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Author |
Tsirlin, A.A.; Abakumov, A.M.; Ritter, C.; Henry, P.F.; Janson, O.; Rosner, H. |
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Title |
Short-range order of Br and three-dimensional magnetism in (CuBr)LaNb2O7 |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
85 |
Issue |
21 |
Pages |
214427 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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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. |
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Wos |
000305557600002 |
Publication Date |
2012-06-22 |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
5 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
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Call Number |
UA @ lucian @ c:irua:100289 |
Serial |
2998 |
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Permanent link to this record |
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Author |
Abakumov, A.M.; Tsirlin, A.A.; Perez-Mato, J.M.; Petřiček, V.; Rosner, H.; Yang, T.; Greenblatt, M. |
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Title |
Spiral ground state against ferroelectricity in the frustrated magnet BiMnFe2O6 |
Type |
A1 Journal article |
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Year |
2011 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
83 |
Issue |
21 |
Pages |
214402-214402,10 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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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. |
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Wos |
000291197400001 |
Publication Date |
2011-06-03 |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
12 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.836; 2011 IF: 3.691 |
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Call Number |
UA @ lucian @ c:irua:90080 |
Serial |
3107 |
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Permanent link to this record |
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Author |
Tsirlin, A.A.; Nath, R.; Abakumov, A.M.; Shpanchenko, R.V.; Geibel, C.; Rosner, H. |
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Title |
Frustrated square lattice with spatial anisotropy: crystal structure and magnetic properties of PbZnVO(PO4)2 |
Type |
A1 Journal article |
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Year |
2010 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
81 |
Issue |
17 |
Pages |
174424,1-174424,13 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Crystal structure and magnetic properties of the layered vanadium phosphate PbZnVO(PO4)2 are studied using x-ray powder diffraction, magnetization and specific-heat measurements, as well as band-structure calculations. The compound resembles AA′VO(PO4)2 vanadium phosphates and fits to the extended frustrated square-lattice model with the couplings J1, J1′ between nearest neighbors and J2, J2′ between next-nearest neighbors. The temperature dependence of the magnetization yields estimates of averaged nearest-neighbor and next-nearest-neighbor couplings, J̅ 1≃−5.2 K and J̅ 2≃10.0 K, respectively. The effective frustration ratio α=J̅ 2/J̅ 1 amounts to −1.9 and suggests columnar antiferromagnetic ordering in PbZnVO(PO4)2. Specific-heat data support the estimates of J̅ 1 and J̅ 2 and indicate a likely magnetic ordering transition at 3.9 K. However, the averaged couplings underestimate the saturation field, thus pointing to the spatial anisotropy of the nearest-neighbor interactions. Band-structure calculations confirm the identification of ferromagnetic J1, J1′ and antiferromagnetic J2, J2′ in PbZnVO(PO4)2 and yield (J1′−J1)≃1.1 K in excellent agreement with the experimental value of 1.1 K, deduced from the difference between the expected and experimentally measured saturation fields. Based on the comparison of layered vanadium phosphates with different metal cations, we show that a moderate spatial anisotropy of the frustrated square lattice has minor influence on the thermodynamic properties of the model. We discuss relevant geometrical parameters, controlling the exchange interactions in these compounds and propose a strategy for further design of strongly frustrated square-lattice materials. |
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Wos |
000278141600082 |
Publication Date |
2010-05-25 |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
27 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.836; 2010 IF: 3.774 |
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Call Number |
UA @ lucian @ c:irua:83384 |
Serial |
1294 |
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Permanent link to this record |
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Author |
Gou, H.; Dubrovinskaia, N.; Bykova, E.; Tsirlin, A.A.; Kasinathan, D.; Schnelle, W.; Richter, A.; Merlini, M.; Hanfland, M.; Abakumov, A.M.; Batuk, D.; Van Tendeloo, G.; Nakajima, Y.; Kolmogorov, A.N.; Dubrovinsky, L.; |
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Title |
Discovery of a superhard iron tetraboride superconductor |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Physical review letters |
Abbreviated Journal |
Phys Rev Lett |
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Volume |
111 |
Issue |
15 |
Pages |
157002-157005 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Single crystals of novel orthorhombic (space group Pnnm) iron tetraboride FeB4 were synthesized at pressures above 8 GPa and high temperatures. Magnetic susceptibility and heat capacity measurements demonstrate bulk superconductivity below 2.9 K. The putative isotope effect on the superconducting critical temperature and the analysis of specific heat data indicate that the superconductivity in FeB4 is likely phonon mediated, which is rare for Fe-based superconductors. The discovered iron tetraboride is highly incompressible and has the nanoindentation hardness of 62(5) GPa; thus, it opens a new class of highly desirable materials combining advanced mechanical properties and superconductivity. |
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Place of Publication |
New York, N.Y. |
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Wos |
000325371500011 |
Publication Date |
2013-10-09 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0031-9007;1079-7114; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
8.462 |
Times cited |
127 |
Open Access |
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Notes |
Countatoms |
Approved |
Most recent IF: 8.462; 2013 IF: 7.728 |
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Call Number |
UA @ lucian @ c:irua:110820 |
Serial |
729 |
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Permanent link to this record |
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Author |
Takatsu, H.; Hernandez, O.; Yoshimune, W.; Prestipino, C.; Yamamoto, T.; Tassel, C.; Kobayashi, Y.; Batuk, D.; Shibata, Y.; Abakumov, A.M.; Brown, C.M.; Kageyama, H. |
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Title |
Cubic lead perovskite PbMoO3 with anomalous metallic behavior |
Type |
A1 Journal article |
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Year |
2017 |
Publication |
Physical review B |
Abbreviated Journal |
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Volume |
95 |
Issue |
15 |
Pages |
155105 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
A previously unreported Pb-based perovskite PbMoO3 is obtained by high-pressure and high-temperature synthesis. This material crystallizes in the Pm3m cubic structure at room temperature, making it distinct from typical Pb-based perovskite oxides with a structural distortion. PbMoO3 exhibits a metallic behavior down to 0.1 K with an unusual T-sublinear dependence of the electrical resistivity. Moreover, a large specific heat is observed at low temperatures accompanied by a peak in C-P/T-3 around 10 K, in marked contrast to the isostructural metallic system SrMoO3. These transport and thermal properties for PbMoO3, taking into account anomalously large Pb atomic displacements detected through diffraction experiments, are attributed to a low-energy vibrational mode, associated with incoherent off-centering of lone-pair Pb2+ cations. We discuss the unusual behavior of the electrical resistivity in terms of a polaronlike conduction, mediated by the strong coupling between conduction electrons and optical phonons of the local low-energy vibrational mode. |
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Wos |
000440605700001 |
Publication Date |
2017-04-04 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2469-9969; 2469-9950 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
no |
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Call Number |
UA @ admin @ c:irua:167288 |
Serial |
7743 |
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Permanent link to this record |
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Author |
Kolchina, L. M.; Lyskov, N.V.; Kuznetsov, A.N.; Kazakov, S.M.; Galin, M.Z.; Meledin, A.; Abakumov, A.M.; Bredikhin, S.I.; Mazo, G.N.; Antipov, E.V. |
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Title |
Evaluation of Ce-doped Pr2CuO4for potential application as a cathode material for solid oxide fuel cells |
Type |
A1 Journal article |
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Year |
2016 |
Publication |
RSC advances |
Abbreviated Journal |
Rsc Adv |
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Volume |
6 |
Issue |
6 |
Pages |
101029-101037 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Pr2−xCexCuO4 (x = 0.05; 0.1; 0.15) samples were synthesized and systematically characterized towards application as a cathode material for solid oxide fuel cells (SOFCs). High-temperature electrical conductivity, thermal expansion, and electrocatalytic activity in the oxygen reduction reaction (ORR) were examined. The electrical conductivity of Pr2−xCexCuO4 oxides demonstrates semiconducting behavior up to 900 °C. Small Ce-doping (2.5 at%) allows an increase in electrical conductivity from 100 to 130 S cm−1 in air at 500–800 °C. DFT calculations revealed that the density of states directly below the Fermi level, comprised mainly of Cu 3d and O 2p states, is significantly affected by atoms in rare earth positions, which might give an indication of a correlation between calculated electronic structures and measured conducting properties. Ce-doping in Pr2−xCexCuO4 slightly increases TEC from 11.9 × 10−6 K−1 for x = 0 to 14.2 × 10−6 K−1 for x = 0.15. Substitution of 2.5% of Pr atoms in Pr2CuO4 by Ce is effective to enhance the electrochemical performance of the material as a SOFC cathode in the ORR (ASR of Pr1.95Ce0.05CuO4 electrode applied on Ce0.9Gd0.1O1.95 electrolyte is 0.39 Ω cm2 at 750 °C in air). The peak power density achieved for the electrolyte-supported fuel cell with the Pr1.95Ce0.05CuO4 cathode is 150 mW cm−2 at 800 °C |
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Corporate Author |
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Thesis |
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Place of Publication |
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Wos |
000387427700044 |
Publication Date |
2016-10-19 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2046-2069 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.108 |
Times cited |
7 |
Open Access |
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Notes |
his work was partially supported by Russian Foundation for Basic Research (grant no. 153820247), Skolkovo Institute of Science and Technology (Center of electrochemical energy), and MSUdevelopment Program up to 2020. K.L.M. is grateful to Haldor Topsøe A/S for the financial support. |
Approved |
Most recent IF: 3.108 |
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Call Number |
EMAT @ emat @ c:irua:136441 |
Serial |
4296 |
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Permanent link to this record |
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Author |
Tsirlin, A.A.; Rousochatzakis, I.; Filimonov, D.; Batuk, D.; Frontzek, M.; Abakumov, A.M. |
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Title |
Spin-reorientation transitions in the Cairo pentagonal magnet Bi4Fe5O13F |
Type |
A1 Journal article |
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Year |
2017 |
Publication |
Physical review B |
Abbreviated Journal |
Phys Rev B |
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Volume |
96 |
Issue |
9 |
Pages |
094420 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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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. |
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Place of Publication |
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Editor |
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Wos |
000411161700002 |
Publication Date |
2017-09-19 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2469-9950 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
7 |
Open Access |
OpenAccess |
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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 |
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Call Number |
EMAT @ emat @c:irua:146748 |
Serial |
4774 |
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Permanent link to this record |
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Author |
Tsirlin, A.A.; Abakumov, A.M.; Ritter, C.; Rosner, H. |
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Title |
(CuCl)LaTa2O\text{7} and quantum phase transition in the (CuX)LaM2O7 family (X=Cl, Br; M=Nb, Ta) |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
86 |
Issue |
6 |
Pages |
064440-12 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
We apply neutron diffraction, high-resolution synchrotron x-ray diffraction, magnetization measurements, electronic structure calculations, and quantum Monte-Carlo simulations to unravel the structure and magnetism of (CuCl)LaTa2O7. Despite the pseudo-tetragonal crystallographic unit cell, this compound features an orthorhombic superstructure, similar to the Nb-containing (CuX)LaNb2O7 with X = Cl and Br. The spin lattice entails dimers formed by the antiferromagnetic fourth-neighbor coupling J(4), as well as a large number of nonequivalent interdimer couplings quantified by an effective exchange parameter J(eff). In (CuCl)LaTa2O7, the interdimer couplings are sufficiently strong to induce the long-range magnetic order with the Neel temperature T-N similar or equal to 7 K and the ordered magnetic moment of 0.53 mu(B), as measured with neutron diffraction. This magnetic behavior can be accounted for by J(eff)/J(4) similar or equal to 1.6 and J(4) similar or equal to 16 K. We further propose a general magnetic phase diagram for the (CuCl)LaNb2O7-type compounds, and explain the transition from the gapped spin-singlet (dimer) ground state in (CuCl)LaNb2O7 to the long-range antiferromagnetic order in (CuCl)LaTa2O7 and (CuBr)LaNb2O7 by an increase in the magnitude of the interdimer couplings J(eff)/J(4), with the (CuCl)LaM2O7 (M = Nb, Ta) compounds lying on different sides of the quantum critical point that separates the singlet and long-range-ordered magnetic ground states. |
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Wos |
000308127600006 |
Publication Date |
2012-08-29 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
6 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
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Call Number |
UA @ lucian @ c:irua:101886 |
Serial |
3526 |
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Permanent link to this record |
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Author |
Gou, H.; Tsirlin, A.A.; Bykova, E.; Abakumov, A.M.; Van Tendeloo, G.; Richter, A.; Ovsyannikov, S.V.; Kurnosov, A.V.; Trots, D.M.; Konôpková, Z.; Liermann, H.P.; Dubrovinsky, L.; Dubrovinskaia, N.; |
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Title |
Peierls distortion, magnetism, and high hardness of manganese tetraboride |
Type |
A1 Journal article |
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Year |
2014 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
89 |
Issue |
6 |
Pages |
064108-64109 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
We report crystal structure, electronic structure, and magnetism of manganese tetraboride, MnB4, synthesized under high-pressure, high-temperature conditions. In contrast to superconducting FeB4 and metallic CrB4, which are both orthorhombic, MnB4 features a monoclinic crystal structure. Its lower symmetry originates from a Peierls distortion of the Mn chains. This distortion nearly opens the gap at the Fermi level, but despite the strong dimerization and the proximity of MnB4 to the insulating state, we find indications for a sizable paramagnetic effective moment of about 1.7 mu(B)/f.u., ferromagnetic spin correlations, and, even more surprisingly, a prominent electronic contribution to the specific heat. However, no magnetic order has been observed in standard thermodynamic measurements down to 2 K. Altogether, this renders MnB4 a structurally simple but microscopically enigmatic material; we argue that its properties may be influenced by electronic correlations. |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000332405000002 |
Publication Date |
2014-02-24 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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|
ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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|
Impact Factor |
3.836 |
Times cited |
39 |
Open Access |
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|
|
Notes |
|
Approved |
Most recent IF: 3.836; 2014 IF: 3.736 |
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Call Number |
UA @ lucian @ c:irua:115819 |
Serial |
2571 |
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Permanent link to this record |
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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.; |
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Title |
Evidence of oxygen-dependent modulation in LuFe2O4 |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
85 |
Issue |
6 |
Pages |
064102-064120,10 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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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. |
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Thesis |
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Place of Publication |
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Editor |
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Language |
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Wos |
000299896900003 |
Publication Date |
2012-02-06 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
24 |
Open Access |
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Notes |
Hercules |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
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Call Number |
UA @ lucian @ c:irua:95042 |
Serial |
1095 |
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Permanent link to this record |
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Author |
Tsirlin, A.A.; Abakumov, A.M.; Van Tendeloo, G.; Rosner, H. |
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Title |
Interplay of atomic displacement in the quantum magnet (CuCI)LaNb2O7 |
Type |
A1 Journal article |
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Year |
2010 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
82 |
Issue |
5 |
Pages |
054107,1-054107,12 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
We report on the crystal structure of the quantum magnet CuClLaNb2O7 that was controversially described with respect to its structural organization and magnetic behavior. Using high-resolution synchrotron powder x-ray diffraction, electron diffraction, transmission electron microscopy, and band-structure calculations, we solve the room-temperature structure of this compound -CuClLaNb2O7 and find two high-temperature polymorphs. The -CuClLaNb2O7 phase, stable above 640 K, is tetragonal with asub=3.889 Å, csub =11.738 Å, and the space group P4/mmm. In the -CuClLaNb2O7 structure, the Cu and Cl atoms are randomly displaced from the special positions along the 100 directions. The phase asub2asubcsub, space group Pbmm and the phase 2asub2asubcsub, space group Pbam are stable between 640 K and 500 K and below 500 K, respectively. The structural changes at 500 and 640 K are identified as order-disorder phase transitions. The displacement of the Cl atoms is frozen upon the → transformation while a cooperative tilting of the NbO6 octahedra in the phase further eliminates the disorder of the Cu atoms. The low-temperature -CuClLaNb2O7 structure thus combines the two types of the atomic displacements that interfere due to the bonding between the Cu atoms and the apical oxygens of the NbO6 octahedra. The precise structural information resolves the controversy between the previous computation-based models and provides the long-sought input for understanding CuClLaNb2O7 and related compounds with unusual magnetic properties. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000280849400001 |
Publication Date |
2010-08-12 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
13 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.836; 2010 IF: 3.774 |
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Call Number |
UA @ lucian @ c:irua:83991 |
Serial |
1706 |
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Permanent link to this record |
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Author |
Blandy, J.N.; Abakumov, A.M.; Christensen, K.E.; Hadermann, J.; Adamson, P.; Cassidy, S.J.; Ramos, S.; Free, D.G.; Cohen, H.; Woodruff, D.N.; Thompson, A.L.; Clarke, S.J.; |
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Title |
Soft chemical control of the crystal and magnetic structure of a layered mixed valent manganite oxide sulfide |
Type |
A1 Journal article |
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Year |
2015 |
Publication |
APL materials |
Abbreviated Journal |
Apl Mater |
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Volume |
3 |
Issue |
3 |
Pages |
041520 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
Oxidative deintercalation of copper ions from the sulfide layers of the layered mixed-valent manganite oxide sulfide Sr2MnO2Cu1.5S2 results in control of the copper-vacancy modulated superstructure and the ordered arrangement of magnetic moments carried by the manganese ions. This soft chemistry enables control of the structures and properties of these complex materials which complement mixed-valent perovskite and perovskite-related transition metal oxides. (C) 2015 Author(s). |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000353828400027 |
Publication Date |
2015-04-21 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2166-532X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.335 |
Times cited |
5 |
Open Access |
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Notes |
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Approved |
Most recent IF: 4.335; 2015 IF: NA |
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Call Number |
c:irua:126021 |
Serial |
3049 |
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Permanent link to this record |
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Author |
Nikolaev, I.V.; d' Hondt, H.; Abakumov, A.M.; Hadermann, J.; Balagurov, A.M.; Bobrikov, I.A.; Sheptyakov, D.V.; Pomjakushin, V.Y.; Pokholok, K.V.; Filimonov, D.S.; Van Tendeloo, G.; Antipov, E.V. |
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Title |
Crystal structure, phase transition, and magnetic ordering in perovskitelike Pb2-xBaxFe2O5 solid solutions |
Type |
A1 Journal article |
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Year |
2008 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
78 |
Issue |
2 |
Pages |
024426,1-12 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Lancaster, Pa |
Editor |
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Language |
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Wos |
000258190200085 |
Publication Date |
2008-07-24 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
29 |
Open Access |
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Notes |
Iap Vi |
Approved |
Most recent IF: 3.836; 2008 IF: 3.322 |
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Call Number |
UA @ lucian @ c:irua:70580 |
Serial |
576 |
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Permanent link to this record |
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Author |
Abakumov, A.M.; Batuk, D.; Tsirlin, A.A.; Prescher, C.; Dubrovinsky, L.; Sheptyakov, D.V.; Schnelle, W.; Hadermann, J.; Van Tendeloo, G. |
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Title |
Frustrated pentagonal Cairo lattice in the non-collinear antiferromagnet Bi4Fe5O13F |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
87 |
Issue |
2 |
Pages |
024423-24429 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
We report on the crystal structure and magnetism of the iron-based oxyfluoride Bi4Fe5O13F, a material prototype of the Cairo pentagonal spin lattice. The crystal structure of Bi4Fe5O13F is determined by a combination of neutron diffraction, synchrotron x-ray diffraction, and transmission electron microscopy. It comprises layers of FeO6 octahedra and FeO4 tetrahedra forming deformed pentagonal units. The topology of these layers resembles a pentagonal least-perimeter tiling, which is known as the Cairo lattice. This topology gives rise to frustrated exchange couplings and underlies a sequence of magnetic transitions at T-1 = 62 K, T-2 = 71 K, and T-N = 178 K, as determined by thermodynamic measurements and neutron diffraction. Below T-1, Bi4Fe5O13F forms a fully ordered non-collinear antiferromagnetic structure, whereas the magnetic state between T-1 and T-N may be partially disordered according to the sizable increase in the magnetic entropy at T-1 and T-2. Bi4Fe5O13F reveals unanticipated magnetic transitions on the pentagonal Cairo spin lattice and calls for a further work on finite-temperature properties of this strongly frustrated spin model. DOI: 10.1103/PhysRevB.87.024423 |
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Corporate Author |
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Thesis |
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Place of Publication |
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Editor |
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Language |
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Wos |
000314224800002 |
Publication Date |
2013-02-01 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
17 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.836; 2013 IF: 3.664 |
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Call Number |
UA @ lucian @ c:irua:107688 |
Serial |
1293 |
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Permanent link to this record |
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Author |
Marikutsa, A.V.; Rumyantseva, M.N.; Frolov, D.D.; Morozov, I.V.; Boltalin, A.I.; Fedorova, A.A.; Petukhov, I.A.; Yashina, L.V.; Konstantinova, E.A.; Sadovskaya, E.M.; Abakumov, A.M.; Zubavichus, Y.V.; Gaskov, A.M.; |
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Title |
Role of PdOx and RuOy clusters in oxygen exchange between nanocrystalline tin dioxide and the gas phase |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
The journal of physical chemistry: C : nanomaterials and interfaces |
Abbreviated Journal |
J Phys Chem C |
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Volume |
117 |
Issue |
45 |
Pages |
23858-23867 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
The effect of palladium- and ruthenium-based clusters on nanocrystalline tin dioxide interaction with oxygen was studied by temperature-programmed oxygen isotopic exchange with mass-spectrometry detection. The modification of aqueous sol-gel prepared SnO2 by palladium and, to a larger extent, by ruthenium, increases surface oxygen concentration on the materials. The revealed effects on oxygen exchange-lowering the threshold temperature, separation of surface oxygen contribution to the process, increase of heteroexchange rate and oxygen diffusion coefficient, decrease of activation energies of exchange and diffusion-were more intensive for Ru-modified SnO2 than in the case of SnO2/Pd. The superior promoting activity of ruthenium on tin dioxide interaction with oxygen was interpreted by favoring the dissociative O-2 adsorption and increasing the oxygen mobility, taking into account the structure and chemical composition of the modifier clusters. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Washington, D.C. |
Editor |
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Language |
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Wos |
000327110500046 |
Publication Date |
2013-10-04 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1932-7447;1932-7455; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.536 |
Times cited |
20 |
Open Access |
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Notes |
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Approved |
Most recent IF: 4.536; 2013 IF: 4.835 |
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Call Number |
UA @ lucian @ c:irua:112706 |
Serial |
2924 |
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Permanent link to this record |
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Author |
Charkin, D.O.; Akinfiev, V.S.; Alekseeva, A.M.; Batuk, M.; Abakumov, A.M.; Kazakov, S.M. |
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Title |
Synthesis and cation distribution in the new bismuth oxyhalides with the Sillen-Aurivillius intergrowth structures |
Type |
A1 Journal article |
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Year |
2015 |
Publication |
Journal of the Chemical Society : Dalton transactions |
Abbreviated Journal |
Dalton T |
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Volume |
44 |
Issue |
44 |
Pages |
20568-20576 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
About 20 new compounds with the Sillen-Aurivillius intergrowth structure, (MeMeBi3Nb2O11X)-Me-1-Bi-2 (Me-1 = Pb, Sr, Ba; Me-2 = Ca, Sr, Ba; X = Cl, Br, I), have been prepared. They are composed of stacking of [ANb(2)O(7)] perovskite blocks, fluorite-type [M2O2] blocks and halogen sheets. The cation distribution between the fluorite and perovskite layers has been studied for Ba2Bi3Nb2O11I, Ca1.25Sr0.75Bi3Nb2O11Cl, BaCaBi3Nb2O11Br and Sr2Bi3Nb2O11Cl. The smaller Me cations tend to reside in the perovskite block while the larger ones are situated in the fluorite-type block. The distribution of the elements was confirmed for BaCaBi3Nb2O11Br using energy dispersive X-ray analysis combined with scanning transmission electron microscopy (STEM-EDX). An electron diffraction study of this compound reveals a local symmetry lowering caused by weakly correlated rotation of NbO6 octahedra. Based on our findings, we suggest a new stability criterion for mixed-layer structures, which is that net charges of any two consecutive layers do not compensate for each other and only the whole layer sequence is electroneutral. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
London |
Editor |
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Language |
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Wos |
000365411500036 |
Publication Date |
2015-10-30 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0300-9246; 1477-9226; 1472-7773 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.029 |
Times cited |
5 |
Open Access |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ lucian @ c:irua:130330 |
Serial |
4256 |
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Permanent link to this record |
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Author |
Lander, L.; Rousse, G.; Abakumov, A.M.; Sougrati, M.; Van Tendeloo, G.; Tarascon, J.-M. |
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Title |
Structural, electrochemical and magnetic properties of a novel KFeSO4F polymorph |
Type |
A1 Journal article |
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Year |
2015 |
Publication |
Journal of materials chemistry A : materials for energy and sustainability |
Abbreviated Journal |
J Mater Chem A |
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Volume |
3 |
Issue |
3 |
Pages |
19754-19764 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
In the quest for sustainable and low-cost positive electrode materials for Li-ion batteries, we discovered, as reported herein, a new low temperature polymorph of KFeSO4F. Contrary to the high temperature phase crystallizing in a KTiOPO4-like structure, this new phase adopts a complex layer-like structure built on FeO4F2 octahedra and SO4 tetrahedra, with potassium cations located in between the layers, as solved using neutron and synchrotron diffraction experiments coupled with electron diffraction. The detailed analysis of the structure reveals an alternation of edge-and corner-shared FeO4F2 octahedra leading to a large monoclinic cell of 1771.774(7) angstrom(3). The potassium atoms are mobile within the structure as deduced by ionic conductivity measurements and confirmed by the bond valence energy landscape approach thus enabling a partial electrochemical removal of K+ and uptake of Li+ at an average potential of 3.7 V vs. Li+/Li-0. Finally, neutron diffraction experiments coupled with SQUID measurements reveal a long range antiferromagnetic ordering of the Fe2+ magnetic moments below 22 K with a possible magnetoelectric behavior. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Cambridge |
Editor |
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Language |
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Wos |
000362041300018 |
Publication Date |
2015-08-17 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2050-7488; 2050-7496 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
8.867 |
Times cited |
11 |
Open Access |
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Notes |
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Approved |
Most recent IF: 8.867; 2015 IF: 7.443 |
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Call Number |
UA @ lucian @ c:irua:132566 |
Serial |
4253 |
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Permanent link to this record |
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Author |
Alekseeva, A.M.; Abakumov, A.M.; Leither-Jasper, A.; Schnelle, W.; Prots, Y.; Van Tendeloo, G.; Antipov, E.V.; Grin, Y. |
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Title |
Spatial separation of covalent, ionic, and metallic interactions in Mg11Rh18B8 and Mg3Rh5B3 |
Type |
A1 Journal article |
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Year |
2013 |
Publication |
Chemistry: a European journal |
Abbreviated Journal |
Chem-Eur J |
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Volume |
19 |
Issue |
52 |
Pages |
17860-17870 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
The crystal structures of Mg11Rh18B8 and Mg3Rh5B3 have been investigated by using single-crystal X-ray diffraction. Mg11Rh18B8: space group P4/mbm; a=17.9949(7), c=2.9271(1)angstrom; Z=2. Mg3Rh5B3: space group Pmma; a=8.450(2), b=2.8644(6), c=11.602(2)angstrom; Z=2. Both crystal structures are characterized by trigonal prismatic coordination of the boron atoms by rhodium atoms. The [BRh6] trigonal prisms form arrangements with different connectivity patterns. Analysis of the chemical bonding by means of the electron-localizability/electron-density approach reveals covalent BRh interactions in these arrangements and the formation of BRh polyanions. The magnesium atoms that are located inside the polyanions interact ionically with their environment, whereas, in the structure parts, which are mainly formed by Mg and Rh atoms, multicenter (metallic) interactions are observed. Diamagnetic behavior and metallic electron transport of the Mg11Rh18B8 and Mg3Rh5B3 phases are in agreement with the bonding picture and the band structure. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Weinheim |
Editor |
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Language |
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Wos |
000328531000028 |
Publication Date |
2013-12-02 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0947-6539; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
5.317 |
Times cited |
5 |
Open Access |
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Notes |
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Approved |
Most recent IF: 5.317; 2013 IF: 5.696 |
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Call Number |
UA @ lucian @ c:irua:113697 |
Serial |
3064 |
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Permanent link to this record |
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Author |
Zaikina, J.V.; Batuk, M.; Abakumov, A.M.; Navrotsky, A.; Kauziarich, S.M. |
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Title |
Facile synthesis of Ba1-xKxFe2As2 superconductors via hydride route |
Type |
A1 Journal article |
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Year |
2014 |
Publication |
Journal of the American Chemical Society |
Abbreviated Journal |
J Am Chem Soc |
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Volume |
136 |
Issue |
48 |
Pages |
16932-16939 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
We have developed a fast, easy, and scalable synthesis method for Ba1xKxFe2As2 (0 ≤ x ≤ 1) superconductors using hydrides BaH2 and KH as a source of barium and potassium metals. Synthesis from hydrides provides better mixing and easier handling of the starting materials, consequently leading to faster reactions and/or lower synthesis temperatures. The reducing atmosphere provided by the evolved hydrogen facilitates preparation of oxygen-free powders. By a combination of methods we have shown that Ba1xKxFe2As2 obtained via hydride route has the same characteristics as when it is prepared by traditional solid-state synthesis. Refinement from synchrotron powder X-ray diffraction data confirms a linear dependence of unit cell parameters upon K content as well as the tetragonal to orthorhombic transition at low temperatures for compositions with x < 0.2. Magnetic measurements revealed dome-like dependence of superconducting transition temperature Tc upon K content with a maximum of 38 K for x close to 0.4. Electron diffraction and high-resolution high-angle annular dark-field scanning transmission electron microscopy indicates an absence of Ba/K ordering, while local inhomogeneity in the Ba/K distribution takes place at a scale of several angstroms along [110] crystallographic direction. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Washington, D.C. |
Editor |
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Language |
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Wos |
000345883900040 |
Publication Date |
2014-11-11 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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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 |
13 |
Open Access |
|
|
|
Notes |
|
Approved |
Most recent IF: 13.858; 2014 IF: 12.113 |
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Call Number |
UA @ lucian @ c:irua:121331 |
Serial |
1169 |
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Permanent link to this record |
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Author |
Kuno, Y.; Tassel, C.; Fujita, K.; Batuk, D.; Abakumov, A.M.; Shitara, K.; Kuwabara, A.; Moriwake, H.; Watabe, D.; Ritter, C.; Brown, C.M.; Yamamoto, T.; Takeiri, F.; Abe, R.; Kobayashi, Y.; Tanaka, K.; Kageyama, H. |
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Title |
ZnTaO2N: Stabilized High-Temperature LiNbO3-type Structure |
Type |
A1 Journal article |
|
Year |
2016 |
Publication |
Journal of the American Chemical Society |
Abbreviated Journal |
J Am Chem Soc |
|
|
Volume |
138 |
Issue |
138 |
Pages |
15950-15955 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
By using a high-pressure reaction, we prepared a new oxynitride ZnTaO2N that crystallizes in a centrosymmetric (R (3) over barc) high-temperature LiNbO3-type structure (HTLN-type). The stabilization of the HTLN-type structure down to low temperatures (at least 20 K) makes it possible to investigate not only the stability of this phase, but also the phase transition to a noncentrosymmetric (R3c) LiNbO3-type structure (LN-type) which is yet to be clarified. Synchrotron and neutron diffraction studies in combination with transmission electron microscopy show that Zn is located at a disordered 12c site instead of 6a, implying an order disorder mechanism of the phase transition. It is found that the dosed d-shell of Zn2+, as well as the high-valent Ta5+ ion, is responsible for the stabilization of the HTLN-type structure, affording a novel quasitriangular ZnO2N coordination. Interestingly, only 3% Zn substitution for MnTaO2N induces a phase transition from LN- to HTLN-type structure, implying the proximity in energy between the two structural types, which is supported by the first-principles calculations. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Washington, D.C. |
Editor |
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Language |
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Wos |
000389962800032 |
Publication Date |
2016-11-18 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
|
Edition |
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ISSN |
0002-7863 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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|
Impact Factor |
13.858 |
Times cited |
13 |
Open Access |
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|
Notes |
|
Approved |
Most recent IF: 13.858 |
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Call Number |
UA @ lucian @ c:irua:140298 |
Serial |
4452 |
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Permanent link to this record |
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Author |
Batuk, D.; Batuk, M.; Tsirlin, A.A.; Hadermann, J.; Abakumov, A.M. |
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Title |
Trapping of Oxygen Vacancies at Crystallographic Shear Planes in Acceptor-Doped Pb-Based Ferroelectrics |
Type |
A1 Journal article |
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Year |
2015 |
Publication |
Angewandte Chemie: international edition in English |
Abbreviated Journal |
Angew Chem Int Edit |
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Volume |
54 |
Issue |
54 |
Pages |
14787-14790 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
The defect chemistry of the ferroelectric material PbTiO3 after doping with Fe(III) acceptor ions is reported. Using advanced transmission electron microscopy and powder X-ray and neutron diffraction, we demonstrate that even at concentrations as low as circa 1.7% (material composition approximately ABO2.95), the oxygen vacancies are trapped into extended planar defects, specifically crystallographic shear planes. We investigate the evolution of these defects upon doping and unravel their detailed atomic structure using the formalism of superspace crystallography, thus unveiling their role in nonstoichiometry in the Pb-based perovskites. |
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Address |
Chemistry Department, Moscow State University, 119991, Moscow (Russia). artem.abakumov@uantwerpen.be |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
English |
Wos |
000367723400031 |
Publication Date |
2015-10-21 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
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|
ISSN |
1433-7851 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
11.994 |
Times cited |
3 |
Open Access |
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|
Notes |
A.M.A. is grateful to the Russian Science Foundation (grant 14-13-00680). AT was funded by the Mobilitas grant MTT77 of the ESF and by the Federal Ministry for Education and Research through the Sofja Kovalevskaya Award of Alexander von Humboldt Foundation. |
Approved |
Most recent IF: 11.994; 2015 IF: 11.261 |
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Call Number |
c:irua:131104 |
Serial |
4080 |
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Permanent link to this record |
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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. |
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Title |
Phase separation and frustrated square lattice magnetism of Na1.5VOPO4F0.5 |
Type |
A1 Journal article |
|
Year |
2011 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
84 |
Issue |
1 |
Pages |
014429-014429,16 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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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. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000293247400008 |
Publication Date |
2011-07-28 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
47 |
Open Access |
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Notes |
|
Approved |
Most recent IF: 3.836; 2011 IF: 3.691 |
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Call Number |
UA @ lucian @ c:irua:91770 |
Serial |
2588 |
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Permanent link to this record |
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Author |
Mikhailova, D.; Reichel, P.; Tsirlin, A.A.; Abakumov, A.M.; Senyshyn, A.; Mogare, K.M.; Schmidt, M.; Kuo, C.Y.; Pao, C.W.; Pi, T.W.; Lee, J.F.; Hu, Z.; Tjeng, L.H.; |
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Title |
Oxygen-driven competition between low-dimensional structures of Sr3CoMO6 and Sr3CoMO7-\delta with M = Ru,Ir |
Type |
A1 Journal article |
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Year |
2014 |
Publication |
Journal of the Chemical Society : Dalton transactions |
Abbreviated Journal |
Dalton T |
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Volume |
43 |
Issue |
37 |
Pages |
13883-13891 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
We have realized a reversible structure transformation of one-dimensional 1D K4CdCl6-type Sr3CoMO6 with the Co2+/M4+ cation ordering into the two-dimensional 2D double layered Ruddlesden-Popper structure Sr3CoMO7-delta with a random distribution of Co and M (with M = Ru, Ir) upon increasing the partial oxygen pressure. The combined soft and hard X-ray absorption spectroscopy studies show that under transformation, Co and M cations were oxidized to Co3+ and M5+. During oxidation, high-spin Co2+ in Sr3CoMO6 first transforms into high-spin Co3+ in oxygen-deficient Sr3CoMO7-delta, and then further transforms into low-spin Co3+ in fully oxidized Sr3CoMO7 upon further increasing the partial pressure of oxygen. The 1D Sr3CoMO6 compound is magnetically ordered at low temperatures with the magnetic moments lying along the c-axis. Their alignment is parallel for Sr3CoRuO6 and antiparallel for Sr3CoIrO6. The 2D compounds reveal a spin-glass-like behavior related to the random distribution of magnetic cations in the structure. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
London |
Editor |
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Language |
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Wos |
000342074100009 |
Publication Date |
2014-07-28 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1477-9226;1477-9234; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.029 |
Times cited |
7 |
Open Access |
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Notes |
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Approved |
Most recent IF: 4.029; 2014 IF: 4.197 |
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Call Number |
UA @ lucian @ c:irua:119960 |
Serial |
2545 |
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Permanent link to this record |
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Author |
Sun, M.; Rousse, G.; Abakumov, A.M.; Van Tendeloo, G.; Sougrati, M.-T.; Courty, M.; Doublet, M.-L.; Tarascon, J.-M. |
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Title |
An oxysulfate Fe2O(SO4)2 electrode for sustainable Li-based batteries |
Type |
A1 Journal article |
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Year |
2014 |
Publication |
Journal of the American Chemical Society |
Abbreviated Journal |
J Am Chem Soc |
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Volume |
136 |
Issue |
36 |
Pages |
12658-12666 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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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. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Washington, D.C. |
Editor |
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Language |
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Wos |
000341544600029 |
Publication Date |
2014-08-14 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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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 |
|
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Notes |
|
Approved |
Most recent IF: 13.858; 2014 IF: 12.113 |
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Call Number |
UA @ lucian @ c:irua:119906 |
Serial |
96 |
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Permanent link to this record |
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Author |
Hadermann, J.; Abakumov, A.M.; Tsirlin, A.A.; Rozova, M.G.; Sarakinou, E.; Antipov, E.V. |
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Title |
Expanding the Ruddlesden-Popper manganite family : the n=3 La3.2Ba0.8Mn3O10 Member |
Type |
A1 Journal article |
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Year |
2012 |
Publication |
Inorganic chemistry |
Abbreviated Journal |
Inorg Chem |
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Volume |
51 |
Issue |
21 |
Pages |
11487-11492 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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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. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Easton, Pa |
Editor |
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Language |
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Wos |
000313220200036 |
Publication Date |
2012-10-17 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0020-1669;1520-510X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.857 |
Times cited |
2 |
Open Access |
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Notes |
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Approved |
Most recent IF: 4.857; 2012 IF: 4.593 |
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Call Number |
UA @ lucian @ c:irua:110121 |
Serial |
1133 |
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Permanent link to this record |
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Author |
Charkin, D.O.; Demchyna, R.; Prots, Y.; Borrmann, H.; Burkhardt, U.; Schwarz, U.; Schnelle, W.; Plokhikh, I.V.; Kazakov, S.M.; Abakumov, A.M.; Batuk, D.; Verchenko, V.Y.; Tsirlin, A.A.; Curfs, C.; Grin, Y.; Shevelkov, A.V.; |
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Title |
Two New Arsenides, Eu7Cu44As23 and Sr7Cu44As23, With a New Filled Variety of the BaHg11 Structure |
Type |
A1 Journal article |
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Year |
2014 |
Publication |
Inorganic chemistry |
Abbreviated Journal |
Inorg Chem |
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Volume |
53 |
Issue |
20 |
Pages |
11173-11184 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Two new ternary arsenides, namely, Eu7Cu44As23 and Sr7Cu44As23, were synthesized from elements at 800 degrees C. Their crystal structure represents a new filled version of the BaHg11 motif with cubic voids alternately occupied by Eu(Sr) and As atoms, resulting in a 2 x 2 x 2 superstructure of the aristotype: space group Fm (3) over barm, a = 16.6707(2) angstrom and 16.7467(2) angstrom, respectively. The Eu derivative exhibits ferromagnetic ordering below 17.5 K. In agreement with band structure calculations both compounds are metals, exhibiting relatively low thermopower, but high electrical and low thermal conductivity. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Easton, Pa |
Editor |
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Language |
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Wos |
000343527700049 |
Publication Date |
2014-09-29 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0020-1669;1520-510X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
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|
Impact Factor |
4.857 |
Times cited |
9 |
Open Access |
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Notes |
|
Approved |
Most recent IF: 4.857; 2014 IF: 4.762 |
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Call Number |
UA @ lucian @ c:irua:121141 |
Serial |
3784 |
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Permanent link to this record |
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Author |
Mefford, J.T.; Rong, X.; Abakumov, A.M.; Hardin, W.G.; Dai, S.; Kolpak, A.M.; Johnston, K.P.; Stevenson, K.J. |
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Title |
Water electrolysis on La1-xSrxCoO3-\delta perovskite electrocatalysts |
Type |
A1 Journal article |
|
Year |
2016 |
Publication |
Nature communications |
Abbreviated Journal |
Nat Commun |
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Volume |
7 |
Issue |
7 |
Pages |
11053 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
Perovskite oxides are attractive candidates as catalysts for the electrolysis of water in alkaline energy storage and conversion systems. However, the rational design of active catalysts has been hampered by the lack of understanding of the mechanism of water electrolysis on perovskite surfaces. Key parameters that have been overlooked include the role of oxygen vacancies, B-O bond covalency, and redox activity of lattice oxygen species. Here we present a series of cobaltite perovskites where the covalency of the Co-O bond and the concentration of oxygen vacancies are controlled through Sr2+ substitution into La1 – xSrxCoO3 – delta. We attempt to rationalize the high activities of La1 – xSrxCoO3 – delta through the electronic structure and participation of lattice oxygen in the mechanism of water electrolysis as revealed through ab initio modelling. Using this approach, we report a material, SrCoO2.7, with a high, room temperature-specific activity and mass activity towards alkaline water electrolysis. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000372721700001 |
Publication Date |
2016-03-23 |
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Series Editor |
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Series Title |
|
Abbreviated Series Title |
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Series Volume |
|
Series Issue |
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Edition |
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ISSN |
2041-1723 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
|
|
Impact Factor |
12.124 |
Times cited |
278 |
Open Access |
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Notes |
Financial support for this work was provided by the R.A. Welch Foundation (grants F-1529 and F-1319). X.R. and A.M.K. acknowledge support from the Skoltech-MIT Center for Electrochemical Energy Storage. Computations were performed using computational resources from XSEDE and NERSC. S.D. was supported as part of the Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences. We thank D.W. Redman for help with the RHE measurements. |
Approved |
Most recent IF: 12.124 |
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Call Number |
UA @ lucian @ c:irua:133242 |
Serial |
4276 |
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Permanent link to this record |
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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.; |
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Title |
{110}-Layered B-cation ordering in the anion-deficient perovskite Pb2.4Ba2.6Fe2Sc2TiO13 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 |
|
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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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. |
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London |
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Wos |
000355701000026 |
Publication Date |
2015-01-26 |
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ISSN |
1477-9226;1477-9234; |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.029 |
Times cited |
1 |
Open Access |
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Approved |
Most recent IF: 4.029; 2015 IF: 4.197 |
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Call Number |
c:irua:127001 |
Serial |
22 |
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Author |
Hadermann, J.; Abakumov, A.M.; Adkin, J.J.; Hayward, M.A. |
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Title |
Topotactic reduction as a route to new close-packed anion deficient perovskites: structure and magnetism of 4H-BaMnO2+x |
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A1 Journal article |
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Year |
2009 |
Publication |
Journal of the American Chemical Society |
Abbreviated Journal |
J Am Chem Soc |
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Volume |
131 |
Issue |
30 |
Pages |
10598-10604 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
The anion-deficient perovskite 4H-BaMnO2+x has been obtained by a topotactic reduction, with LiH, of the hexagonal perovskite 4H-BaMnO3−x. The crystal structure of 4H-BaMnO2+x was solved using electron diffraction and X-ray powder diffraction and further refined using neutron powder diffraction (S.G. Pnma, a = 10.375(2) Å, b = 9.466(2) Å, c = 11.276(3) Å, at 373 K). The orthorhombic superstructure arises from the ordering of oxygen vacancies within a 4H (chch) stacking of close packed c-type BaO2.5 and h-type BaO1.5 layers. The ordering of the oxygen vacancies transforms the Mn2O9 units of face-sharing MnO6 octahedra into Mn2O7 (two corner-sharing tetrahedra) and Mn2O6 (two edge-sharing tetrahedra) groups. The Mn2O7 and Mn2O6 groups are linked by corner-sharing into a three-dimensional framework. The structures of the BaO2.5 and BaO1.5 layers are different from those observed previously in anion-deficient perovskites providing a new type of order pattern of oxygen atoms and vacancies in close packed structures. Magnetization measurements and neutron diffraction data reveal 4H-BaMnO2+x adopts an antiferromagnetically ordered state below TN ≈ 350 K. |
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Washington, D.C. |
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000268644400056 |
Publication Date |
2009-07-01 |
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ISSN |
0002-7863;1520-5126; |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
13.858 |
Times cited |
25 |
Open Access |
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Notes |
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Approved |
Most recent IF: 13.858; 2009 IF: 8.580 |
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Call Number |
UA @ lucian @ c:irua:77928 |
Serial |
3681 |
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