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[en] The compounds Rh2U6S15, Cs2Ti2U6Se15, Cs2Cr2U6Se15, and Cs2Ti2U6Te15 have been synthesized at 1173 K. All crystallize in space group O9h - Im3-bar -m of the cubic system. Rh2U6S15 has a framework structure with three-dimensional channels. The compounds Cs2Ti2U6Se15, Cs2Cr2U6Se15, and Cs2Ti2U6Te15 have structures similar to that of Rh2U6S15, but with Cs cations variably filling the channels. In all four structures the transition element is octahedrally coordinated by chalcogens and the uranium atom is in a bi-capped trigonal-prismatic arrangement. The temperature dependence of the magnetic susceptibility of Cs2Cr2U6Se15 implies both Cr and U magnetic contributions. From these data the compound is not antiferromagnetic, but it could have either a ferrimagnetic or a ferromagnetic ground state. (authors)
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Available from doi: http://dx.doi.org/10.1016/j.jssc.2015.04.005; 41 refs.; Country of input: France
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Journal of Solid State Chemistry; ISSN 0022-4596;
; v. 228; p. 14-19

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[en] A new quaternary uranium(V) selenide, Ba8PdU2Se12(Se2)2, has been synthesized by reaction of elements at 1173 K. A single-crystal X-ray diffraction study shows that the compound crystallizes in a new structure type with two formula units in space group D2h12-Pnnm of the orthorhombic crystal system with cell constants of a=9.490(1), b=12.240(2),and c=13.780(3) Angstroms. Its crystal structure consists of [PdU2Se1212-] units where U atoms are coordinated to six Se atoms in octahedral geometry and Pd atoms are coordinated to four Se atoms in square-planar geometry.These [PdU2Se1212-] units are separated by Ba to result in a salt-like crystal structure. This compound also contains Se22- dimers that are part of Ba coordination polyhedra. The formula charge balances as (Ba2+)8(Pd2+)(U5+)2(Se2-)12(Se22-)2. Theoretical calculations predict antiferromagnetic semiconducting behavior for this compound with a band gap of 1.6 eV. Temperature-dependent four-probe resistivity measurements on single crystal confirm the semiconducting nature with an activation energy of 0.18(1)eV. (authors)
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Available from doi: http://dx.doi.org/10.1016/j.jssc.2015.06.033; 54 refs.; Country of input: France
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Journal of Solid State Chemistry; ISSN 0022-4596;
; v. 230; p. 70-74

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[en] The rare earth oxysulfate series Ln2O2SO4 (Ln = La, Gd, Y) was synthesized by two different thermal decomposition methods. The complex ion (LnO)nsup n+/) existing in the structure of various oxysalts seems to have a major effect on the appearance of the spectra. Then it is possible to derive sets of crystal field parameters simulating the spectra, by using the C4v → C2v descending symmetry procedure. Moreover, an alternative method for determining these parameters is described when a C2v point site symmetry is distorted from D3h
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Journal of Solid State Chemistry; ISSN 0022-4596;
; v. 46 p. 101-111

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AbstractAbstract
[en] Two new ternary lanthanide (Ln) uranium selenides, Er3USe8 and Yb3USe8, were synthesized at 1198 K using NaI as a flux. Single-crystal X-ray studies show these two compounds to be isostructural and to crystallize in space group D2h 11-Pbcm of the orthorhombic crystal system. The Ln and U atoms are disordered on the same crystallographic site in these crystal structures. Each Ln/U atom is coordinated to eight Se atoms in a bi-capped trigonal prism, and sharing of these (Ln/U)Se8 units creates a three-dimensional network. Se2 atoms are connected to each other to form infinite one-dimensional chains along the c axis. In these chains, the two Se atoms are separated by about 2.74 Angstroms, a distance intermediate to those of a Se-Se single bond and a van der Waals interaction. Temperature-dependent resistivity measurements show that Er3USe8 and Yb3USe8 are semiconductors with activation energies of 0.08 (1) and 0.17(1)eV, respectively. (authors)
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Available from doi: http://dx.doi.org/10.1016/j.jssc.2015.10.003; 44 refs.; Country of input: France
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Journal of Solid State Chemistry; ISSN 0022-4596;
; v. 233; p. 90-94

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AbstractAbstract
[en] The isothermal decomposition of any ternary oxide A/sub x/B/sub y/O/sub z/ on liberation of n moles of oxygen at a constant pressure is found to be driven by the mixing entropy ΔS/sub m/ = -nRlnP/sub O2/ of the total entropy change ΔS = ΔS0 + ΔS/sub m/. The stability of A/sub x/B/sub y/O/sub z/ towards isothermal decomposition into a biphasic solid mixture is derived from the equilibrium condition ΔG* = 0 as functions of standard changes ΔH0 and ΔS0. Assuming ΔS0 = 44n and calculating ΔH0 in terms of lattice energies U(ABO3) and U(A2O3), the stability of perovskites St(ABO3) = -logP*/sub O2/(A = La, Sm, Dy; B = Mn, Fe) is given as a function of the ionic radius of the A3+ ion. The calculated stability agrees well with that observed. The effect of electronic entropy change ΔS/sub e/ on ΔS0 is demonstrated for AFeO3
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Journal of Solid State Chemistry; ISSN 0022-4596;
; v. 38(2); p. 229-238

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[en] The heat of reaction and equilibrium pressure for the oxidation reaction TbO/sub 1.5 + x/ + (3/28 - x/2)O2 → (1/7)Tb7O12 have been measured by means of a Tian-Calvet-type calorimeter and a thermal balance. The results of the weight measurement show a reproducible hysteresis loop. The heat of reaction has been measured along the oxidation branch of the hysteresis loop. The partial molar enthalpy indicates four distinct compositional regions. First, the TbO/sub 1.5 + x/ region which can be described in terms of a point defect model and strong interaction between neighboring excess oxygen atoms. Second, the region between TbO154 and TbO161 is interpreted as the intrinsic hysteresis region and discussed in terms of the regular solution model. Third, the region between TbO161 and TbO170 is recognized as a pseudophase region. Fourth, a region of eta phase exists in which the partial thermodynamic quantities can be compared with those of CeO1714, PrO1714, and TbO1714. The partial molar enthalpy was also measured for a scanning loop which is also interpreted in terms of the four regimes
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Journal of Solid State Chemistry; ISSN 0022-4596;
; v. 37(1); p. 77-84

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[en] Two samples containing 2-line ferrihydrite and copper oxide were synthesized by coprecipitation method, via variation of Fe3+ and Cu2+ precursors milimolar ratio (3:1 and 3:3.1), while the other synthesis parameters were kept constant. Annealing treatment at 1100 °C resulted in the formation of c-CuFe2O4-CuO-α-Fe2O3 and c-CuFe2O4-CuO nanocomposites, respectively. A comparison of properties of the prepared samples was performed by XRD, FTIR and EPR measurements. Formation mechanism of the nanocomposites is discussed with a reference to the influence of Jahn-Teller effect in CuO phase on the final CuFe2O4 structure. For the first time, it is shown that the amount of Fe3+ precursor is of key importance for the size of CuFe2O4 nanoparticles, and enables preparation of c-CuFe2O4 nanoparticles of the same crystallite size (46 nm) in different nanocomposite materials. © 2019 Elsevier Inc.
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Available from https://linkinghub.elsevier.com/retrieve/pii/S002245961930177X; OAI: vinar.vin.bg.ac.rs:123456789/8160; Country of input: Serbia
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Journal of Solid State Chemistry (Print); ISSN 0022-4596;
; v. 275; p. 187-196

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[en] The phase relations in the Yb2O3-Fe2O3-CoO system at 1350 and 13000C, the Yb2O3-Fe2O3-NiO system at 1300 and 12000C, the Yb2O3-Fe2O3-CuO system at 10000C, and the Yb2O3-Fe2O3-ZnO system at 13000C were determined in air by means of a classical quenching method. New layered-type compounds, YbFeCoO4 (a = 3.4295(5) angstrom, c = 25.198(3) angstrom), YbFeCuO4 (a = 3.4808(2) angstrom, c = 24.100(2) angstrom), and YbFeZnO4 (a = 3.4251(2) angstrom), c = 25.282(2) angstrom), which are isomorphous with YbFe2O4 (space group: R3m; a = 3.455(1) angstrom, c = 25.109(2) angstrom), and a new compound, Yb2Cu2O5, were obtained. In the Yb2O3-Fe2O3-NiO system, there are no quaternary compounds
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Journal of Solid State Chemistry; ISSN 0022-4596;
; v. 42(1); p. 22-27

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[en] The selenide systems of niobium and tantalum were investigated under high pressures in the composition limits of MX2 to MX3. Two distinct phases, NbSe2 and NbSe3, were obtained in the niobium system. In the tantalum system, there were three phases, TaSe2, ''TaSe3,'' which has been thought of as a triselenide, and stoichiometric TaSe3. The ratio of Se/Ta in ''TaSe3'' was 2.8. Conversions of the triselenides under high pressure to NbSe2 or TaSe2 were observed at the starting composition of Se/M = 2.0 and to ''TaSe3'' at Se/Ta = 2.8
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Journal of Solid State Chemistry; ISSN 0022-4596;
; v. 41(3); p. 323-328

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[en] La3WO6GAMMAl3 is representative of a group of rare earth chlorotungstates, where Ln can also be Ce, Pr, Nd, Sm, Eu, and Gd. The structure was determined and refined to an R value of 3.5%. The space group is P63/m with La in 10-coordination and W in an unusual trigonally prismatic 6-coordination. The local site symmetry for W is D3h. Powder diffraction data are reported for La3WO6Cl3. Diffuse reflectance, ir, Raman, and luminescence spectra are reported for pure La3WO6Cl3, as well as for the activators Sm, Eu, Tb, Dy, and Tm incorporated into this host
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Journal of Solid State Chemistry; ISSN 0022-4596;
; v. 44(1); p. 99-107

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