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Author |
Zhang, H.; Yang, J.-H.; Shpanchenko, R.V.; Abakumov, A.M.; Hadermann, J.; Clérac, R.; Dikarev, E.V. |
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Title |
New class of single-source precursors for the synthesis of main group-transition metal oxides: heterobimetallic Pb-Mn \beta-diketonates |
Type |
A1 Journal article |
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Year |
2009 |
Publication |
Inorganic chemistry |
Abbreviated Journal |
Inorg Chem |
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Volume |
48 |
Issue |
17 |
Pages |
8480-8488 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Heterometallic lead−manganese â-diketonates have been isolated in pure form by several synthetic methods that include solid-state and solution techniques. Two compounds with different Pb/Mn ratios, PbMn2(hfac)6 (1) and PbMn(hfac)4 (2) (hfac = hexafluoroacetylacetonate), can be obtained in quantitative yield by using different starting materials. Single crystal X-ray investigation revealed that the solid-state structure of 1 contains trinuclear molecules in which lead metal center is sandwiched between two [Mn(hfac)3] units, while 2 consists of infinite chains of alternating [Pb(hfac)2] and [Mn(hfac)2] fragments. The heterometallic structures are held together by strong Lewis acid−base interactions between metal atoms and diketonate ligands acting in chelating-bridging fashion. Spectroscopic investigation confirmed the retention of heterometallic structures in solutions of non-coordinating solvents as well as upon sublimation-deposition procedure. Thermal decomposition of heterometallic diketonates has been systematically investigated in a wide range of temperatures and annealing times. For the first time, it has been shown that thermal decomposition of heterometallic diketonates results in mixed-metal oxides, while both the structure of precursors and the thermolysis conditions have a significant influence on the nature of the resulting oxides. Five different Pb−Mn oxides have been detected by X-ray powder diffraction when studying the decomposition of 1 and 2 in the temperature range 500−800 °C. The phase that has been previously reported as Pb0.43MnO2.18 was synthesized in the pure form by decomposition of 1, and crystallographically characterized. The orthorhombic unit cell parameters of this oxide, obtained by electron diffraction technique, have been subsequently refined using X-ray powder diffraction data. Besides that, a previously unknown lead−manganese oxide has been obtained at low temperature decomposition and short annealing times. The parameters of its monoclinically distorted unit cell have been determined. The EDX analysis revealed that this compound has a Pb/Mn ratio close to 1:4 and contains no appreciable amount of fluorine. |
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Place of Publication |
Easton, Pa |
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Wos |
000269313500056 |
Publication Date |
2009-08-04 |
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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 |
28 |
Open Access |
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Notes |
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Approved |
Most recent IF: 4.857; 2009 IF: 4.657 |
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Call Number  |
UA @ lucian @ c:irua:78486 |
Serial |
2308 |
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Author |
Abakumov, A.M.; Hadermann, J.; Tsirlin, A.A.; Tan, H.; Verbeeck, J.; Zhang, H.; Dikarev, E.V.; Shpanchenko, R.V.; Antipov, E.V. |
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Title |
Original close-packed structure and magnetic properties of the Pb4Mn9O20 manganite |
Type |
A1 Journal article |
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Year |
2009 |
Publication |
Journal of solid state chemistry |
Abbreviated Journal |
J Solid State Chem |
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Volume |
182 |
Issue |
8 |
Pages |
2231-2238 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
The crystal structure of the Pb4Mn9O20 compound (previously known as Pb0.43MnO2.18) was solved from powder X-ray diffraction, electron diffraction, and high resolution electron microscopy data (S.G. Pnma, a=13.8888(2) Å, b=11.2665(2) Å, c=9.9867(1) Å, RI=0.016, RP=0.047). The structure is based on a 6H (cch)2 close packing of pure oxygen h-type (O16) layers alternating with mixed c-type (Pb4O12) layers. The Mn atoms occupy octahedral interstices formed by the oxygen atoms of the close-packed layers. The MnO6 octahedra share edges within the layers, whereas the octahedra in neighboring layers are linked through corner sharing. The relationship with the closely related Pb3Mn7O15 structure is discussed. Magnetization measurements reveal a peculiar magnetic behavior with a phase transition at 52 K, a small net magnetization below the transition temperature, and a tendency towards spin freezing. |
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Place of Publication |
London |
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Wos |
000269066400035 |
Publication Date |
2009-06-12 |
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Edition |
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ISSN |
0022-4596; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.299 |
Times cited |
5 |
Open Access |
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Notes |
The authors are grateful to Christoph Geibel for the help in magnetization measurements. A.Ts. acknowledges MPI CKS for hospitality and financial support during the stay. E.D. thanks the National Science Foundation (CHE-0718900) for financial support. This work was supported by the Russian Foundation of Basic Research (RFBR Grants 07-03-00664-a, 06-03-90168-a and 07-03-00890-a). The authors acknowledge financial support from the European Union under the Framework 6 program under a contract for an Integrated Infrastructure Initiative. Reference 026019 ESTEEM. |
Approved |
Most recent IF: 2.299; 2009 IF: 2.340 |
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Call Number |
UA @ lucian @ c:irua:78935UA @ admin @ c:irua:78935 |
Serial |
2529 |
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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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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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Author |
Navulla, A.; Tsirlin, A.A.; Abakumov, A.M.; Shpanchenko, R.V.; Zhang, H.; Dikarev, E.V. |
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Title |
Fluorinated heterometallic \beta-diketonates as volatile single-source precursors for the synthesis of low-valent mixed-metal fluorides |
Type |
A1 Journal article |
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Year |
2011 |
Publication |
Journal of the American Chemical Society |
Abbreviated Journal |
J Am Chem Soc |
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Volume |
133 |
Issue |
4 |
Pages |
692-694 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Hexafluoroacetylacetonates that contain lead and divalent first-row transition metals, PbM(hfac)4 (M = Ni (1), Co (2), Mn (3), Fe (4), and Zn (5)), have been synthesized. Their heterometallic structures are held together by strong Lewis acid−base interactions between metal atoms and diketonate ligands acting in chelating−bridging fashion. Compounds 1−5 are highly volatile and decompose below 350 °C. Fluorinated heterometallic β-diketonates have been used for the first time as volatile single-source precursors for the preparation of mixed-metal fluorides. Complex fluorides of composition Pb2MF6 have been obtained by decomposition of 1−5 in a two-zone furnace under low-pressure nitrogen flow. Lead−transition metal fluorides conform to orthorhombically distorted Aurivillius-type structure with layers of corner-sharing [MF6] octahedra separated by α-PbO-type (Pb2F2) blocks. Pb2NiF6 and Pb2CoF6 were found to exhibit magnetic ordering below 80 and 43 K, respectively. The ordering is antiferromagnetic, with a weak, uncompensated moment due to the canting of spins. The Pb2MF6 fluorides represent a new class of prospective magnetoelectric materials combining transition metals and lone-pair main-group cations. |
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Place of Publication |
Washington, D.C. |
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Wos |
000287295300015 |
Publication Date |
2010-12-21 |
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Edition |
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ISSN |
0002-7863;1520-5126; |
ISBN |
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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 |
28 |
Open Access |
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Notes |
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Approved |
Most recent IF: 13.858; 2011 IF: 9.907 |
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Call Number |
UA @ lucian @ c:irua:88820 |
Serial |
1236 |
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Author |
Antipov, E.V.; Putilin, S.N.; Shpanchenko, R.V.; Alyoshin, V.A.; Rozova, M.G.; Abakumov, A.M.; Mikhailova, D.A.; Balagurov, A.M.; Lebedev, O.; Van Tendeloo, G. |
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Title |
Structural features, oxygen and fluorine doping in Cu-based superconductors |
Type |
A1 Journal article |
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Year |
1997 |
Publication |
Physica: C : superconductivity
T2 – International Conference on Materials and Mechanisms of, Superconductivity – High Temperature Superconductors V, Feb. 28-Mar. 04, 1997, Beijing, Peoples R. China |
Abbreviated Journal |
Physica C |
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Volume |
282 |
Issue |
Part 1 |
Pages |
61-64 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
The variation of structures and superconducting properties by changing extra oxygen or fluorine atoms concentration in Hg-based Cu mixed oxides and YBa2Cu3O6+delta was studied. The data obtained by NPD study of Hg-1201 can be considered as an evidence of the conventional oxygen doping mechanism with 2 delta holes per (CuO2) layer. The extra oxygen atom was found to be located in the middle of the Hg mesh only. Different formal charges of oxygen and fluorine inserted into reduced 123 structure results in its distinct variations. The fluorine incorporation into strongly reduced YBa2Cu3O6+delta causes a significant structural rearrangement and the formation of a new compound with a composition close to YBa2Cu3O6F2 (tetragonal alpha = 3.87 Angstrom and c approximate to 13 Angstrom), which structure was deduced from the combined results of X-ray diffraction, electron diffraction and high resolution electron microscopy. Fluorination treatment by XeF2 of nonsuperconducting 123 samples causes an appearance of bulk superconductivity with T-c up to 94K. |
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Elsevier Science |
Place of Publication |
Amsterdam |
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Wos |
A1997XZ90400019 |
Publication Date |
2002-07-25 |
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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 |
0921-4534; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
1.404 |
Times cited |
10 |
Open Access |
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Notes |
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Approved |
Most recent IF: 1.404; 1997 IF: 2.199 |
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Call Number |
UA @ lucian @ c:irua:95866 |
Serial |
3237 |
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