| 1. |
- Ivanov, Sergey A., et al.
(författare)
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Perovskite solid solutions La0.75Bi0.25Fe1-xCrxO3 : Preparation, structural, and magnetic properties
- 2017
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Ingår i: Journal of Solid State Chemistry. - : Elsevier. - 0022-4596 .- 1095-726X. ; 254, s. 166-177
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Tidskriftsartikel (refereegranskat)abstract
- Solid solutions of La0.75Bi0.25Fe1−xCrxO3 (x = 0.1, 0.25, 0.5, and 0.75) prepared by conventional solid state reaction have been studied by means of X-ray powder diffraction (XRPD), neutron powder diffraction (NPD) and magnetic measurements. The NPD and XRPD patterns indicate orthorhombic structure (space group Pnma) for all compositions in the whole temperature range investigated (4–900 K). The lattice parameters of La0.75Bi0.25Fe1−xCrxO3 were found to decrease with the Cr content. It was established that the Fe3+ and Cr3+ cations are randomly positioned at the B-site of the perovskite structure.All samples order antiferromagnetically below transition temperatures that decrease with increasing Cr content, from around 700 K for x = 0.1 to about 300 K for x = 0.75. The antiferromagnetic arrangement of the Fe3+/Cr3+ magnetic moments in the B-site is of G-type along the x-axis (Gx mode) with propagation vector k = (0,0,0) for all concentrations of Cr. Effects of the composition on several structural distortion parameters were investigated and an anomalous variation of the octahedral deformation with Cr content was found. Whilst the overall octahedral deformation varies irregularly with increasing Cr content, the octahedral tilting was found to decrease monotoneously.
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| 2. |
- Ivanov, Sergey A, et al.
(författare)
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Structural and magnetic properties of Mn3-xCdxTeO6 (x = 0, 1, 1.5 and 2)
- 2012
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 324:8, s. 1637-1644
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Tidskriftsartikel (refereegranskat)abstract
- Mn(3)TeO(6) exhibits a corundum-related A(3)TeO(6) structure and a complex magnetic structure involving two magnetic orbits for the Mn atoms [Ivanov et al., 2011 [3]]. Mn(3-x)Cd(x)TeO(6) (x = 0, 1, 1.5, and 2) ceramics were synthesized by solid state reaction and investigated using X-ray powder diffraction, electron microscopy, and calorimetric and magnetic measurements. Cd(2+) replaces Mn(2+) cations without greatly affecting the structure of the compound. The Mn and Cd cations were found to be randomly distributed over the A-site. Magnetization measurements indicated that the samples order antiferromagnetically at low temperature with a transition temperature that decreases with increasing Cd doping. The nuclear and magnetic structure of one specially prepared (114)Cd containing sample: Mn(1.5) (114)Cd(1.5)TeO(6), was studied using neutron powder diffraction over the temperature range 2-295 K. Mn(1.5) (114)Cd(1.5)TeO(6) was found to order in an incommensurate helical magnetic structure, very similar to that of Mn(3)TeO(6) [Ivanov et al., 2011 [3]]. However, with a lower transition temperature and the extension of the ordered structure confined to order 240(10) angstrom.
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| 3. |
- Ivanov, Sergey, et al.
(författare)
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Cation ordering, ferrimagnetism and ferroelectric relaxor behavior in Pb(Fe1-xScx)(2/3)W1/3O3 solid solutions
- 2019
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Ingår i: European Physical Journal B. - : SPRINGER. - 1434-6028 .- 1434-6036. ; 92:8
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Tidskriftsartikel (refereegranskat)abstract
- Ceramic samples of the multiferroic perovskite Pb(Fe1-xScx)(2/3)W1/3O3 with 0 <= x <= 0.4 have been synthesized using a conventional solid-state reaction method, and investigated experimentally and theoretically using first-principle calculations. Rietveld analyses of joint synchrotron X-ray and neutron diffraction patterns show the formation of a pure crystalline phase with cubic (Fm3(_)m) structure with partial ordering in the B-sites. The replacement of Fe by Sc leads to the increase of the cation order between the B and B '' sites. As the non-magnetic Sc3+ ions replace the magnetic Fe3+ cations, the antiferromagnetic state of PbFe2/3W1/3O3 is turned into a ferrimagnetic state reflecting the different magnitude of the magnetic moments on the B ' and B '' sites. The materials remain ferroelectric relaxors with increasing Sc content. Results from experiments on annealed and quenched samples show that the cooling rate after high temperature annealing controls the degree of cationic order in Pb(Fe1-xScx)(2/3)W1/3O3 and possibly also in the undoped PbFe2/3W1/3O3.
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| 4. |
- Ivanov, Sergey, et al.
(författare)
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Short-Range Spin Order and Frustrated Magnetism in Mn(2)InSbO(6) and Mn(2)ScSbO(6)
- 2011
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Ingår i: European Journal of Inorganic Chemistry. - : Wiley. - 1434-1948 .- 1099-1948 .- 1099-0682. ; :30, s. 4691-4699
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Tidskriftsartikel (refereegranskat)abstract
- The complex metal oxides Mn(2)ASbO(6) (A = In, Sc) with a corundum-related structure A(3)BO(6) were prepared as polycrystalline powders by a solid-state reaction route. Their crystal structure and magnetic properties were investigated by using a combination of X-ray and neutron powder diffraction, electron microscopy, calorimetric, and magnetic measurements. At room temperature, these compounds adopt a trigonal structure, space group R (3) over bar, with a = 8.9313(1) angstrom, c = 10.7071(2) angstrom (for In) and a = 8.8836(1) angstrom, c = 10.6168(2) angstrom (for Sc), which persists down to 1.6 K. The Mn and A cations were found to be randomly distributed over the A sites. The overall behavior of the magnetization of Mn(2)InSbO(6) and that of Mn(2)ScSbO(6) are quite similar. In spite of the relatively large amount of Mn ions on the A site, only short-range magnetism is observed. Neutron diffraction patterns of Mn(2)InSbO(6) showed no evidence of a long-range magnetic ordering at 1.6 K, instead only a weak diffuse magnetic peak was observed at low temperatures. The factors governing the observed structural and magnetic properties of Mn(2)ASbO(6) are discussed and compared with those of other Mn-containing complex metal oxides with a corundum-related structure. The influence of the A cation sublattice on the magnetic properties is also considered.
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| 5. |
- Tellgren, Roland, 1930-, et al.
(författare)
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Substitution mechanism and structural study of Ag-doped LiCu2O2
- 2017
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Ingår i: Solid State Sciences. - : ELSEVIER SCIENCE BV. - 1293-2558 .- 1873-3085. ; 70, s. 36-40
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Tidskriftsartikel (refereegranskat)abstract
- Plate-like stoichiometric crystals of Ag-doped LiCu2O2 have been grown by slowly cooling Li2CO3 center dot 4(1 - x)CuO center dot 4xAgNO(3) (0 <= x <= 0.5) melts. X-ray single crystal diffraction has shown that the crystals are isostructural with LiCu2O2 and contain around 5 at % Ag (relative to the Cu atoms). The addition of silver to lithium cuprate crystals significantly increases their electrical conductivity but has little effect on the temperature behavior of their magnetic moment. The possible substitution mechanism is determined which supports Ag+ <-> Cu+, rather than Ag+ <-> Li+ in the Ag-doped LiCu2O2 crystals.
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| 6. |
- Maletka, Krzysztof, et al.
(författare)
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Crystalline structures of Rb2UBr6 ionic conductor determined by neutron diffraction
- 2020
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Ingår i: Nukleonika. - : INST NUCLEAR CHEMISTRY TECHNOLOGY. - 0029-5922 .- 1508-5791. ; 65:1, s. 3-11
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Tidskriftsartikel (refereegranskat)abstract
- The neutron powder diffraction technique has been used for structural studies of Rb2UBr6 solid electrolyte as a function of temperature. The low-, room-, and high-temperature structures have been determined. At the temperature range of 4.2-80 K, the compound crystallizes in a monoclinic unit cell in the P21/c space group. At 80 K and 853 K, the compound crystallizes in a tetragonal unit cell in the P4/mnc space group. At 300 K, the lattice constants are a = b = 7.745(1) and c = 11.064(1) (a) over bar. At the temperature range of 853-960 K, a trigonal phase is observed in the P (3) over bar ml space group.
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