Solid Compounds of Transition Elements II

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Authors: Iryna Tokaychuk, Yaroslav Tokaychuk, Roman E. Gladyshevskii
Abstract: The structure of the new ternary compound Hf2GaSb3 was determined by means of X-ray powder diffraction. It crystallizes with the structure type Zr2CuSb3 which represents a ternary ordered derivative of the UAs2 type (Pearson symbol tP6, space group P-4m2, a = 3.89841(8), c = 8.62650(19) Å). The ternary compound can be regarded as an ordered, Ga-stabilized derivative of the high-temperature modification of the binary antimonide HfSb2 (structure type UAs2).
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Authors: Yuriy Verbovytskyy, Antonio Pereira Gonçalves
Abstract: Seven new ternary RZn1+xGa3-x (R = Ce, Pr, Nd, Sm, Ho and Er) and R5Zn2Ga17 (R = Ce) phases are synthesized for the first time. Their crystal structures are solved on basis of X-ray powder diffraction data. The above mentioned compounds belong to the BaAl4 (space group I4/mmm) and Rb5Hg19 (space group I4/m) structure types. Details of the structure of the Ce5Zn2Ga17 compound and relationship with RZn2-xGa2+x (BaAl4 type) and R3Zn8-xGa3+x (La3Al11 type) are briefly discussed.
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Authors: Markus Hainz, Herbert Boller
Abstract: Rb3Mo14O22 has been prepared and its crystal structure determined: S.G.: P21/c (No.14), a = 10.462(7), b = 9.414(2), c = 9.956(5) Ǻ, β = 103.73(2)°, Z = 2, R = 0.046. It is isotypic to K3Mo14O22. The crystal structure can be described as a substitutional derivative of a ccp close packing of oxygen and rubidium atoms with interspersed Mo14O34 units having a core of three trans-edge condensed molybdenum octahedra. The observed multiple twinning is explained by this structural model. A bond valence analysis is presented.
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Authors: Tetiana Kosorukova, Volodymir Ivanchenko, Georgiy Firstov, Henri Noël
Abstract: Phase equilibria in the Ni-Zr system were experimentally reinvestigated by means of differential thermal, electron microprobe, X-Ray diffraction and metallographic analyses of the alloys, which were prepared by arc melting and then annealed at 900°C during 2 weeks. The temperatures of equilibria reactions in Ni-Zr systems were specified and phase diagram Ni-Zr was reconstructed.
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Authors: Margarida S. Henriques, Thomas Malnoe, Olivier Tougait, Rui Vilar, Antonio Pereira Gonçalves
Abstract: A systematic study on the ternary uranium-iron-antimony was made at 700 and 750°C through powder X-ray diffraction and Scanning Electron Microscopy coupled with Energy Dispersive Spectrometry. The assessed sections confirmed the existence and crystal structure of the binary intermetallic compounds as well as the ternary phase UFeSb2. Moreover it was found that UFeSb2 is part of a solid solution, UFe1-xSb2, stable for 193Fe3-xSb4, crystallizing in the cubic type Y3Au3Sb4 and stable for 22
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Authors: Matthieu Peniel, Houda El Bekkachi, Olivier Tougait, Mathieu Pasturel, Henri Noël
Abstract: The isothermal sections of the U-Mo-C ternary system have been established at 1000°C and 1400°C, using powder X-ray diffraction, scanning electron microscopy coupled with energy dispersive X-ray analysis for the quantification of U and Mo and differential thermal analysis. The main differences between the two sections are the appearance of liquid phase at about 1230°C, due to the peritectic decomposition of γ-UMo, and the peritectoid decompositions of MoC and β’’ Mo2C. No other transformation was detected in this temperature range, especially one involving the two only ternary phases found, UMoC2 and U2Mo2C3.
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Authors: K.A. Lorenzer, P. Dalladay Simpson, F. Kubel, A. Sidorenko, A. Prokofiev, S. Paschen
Abstract: Here we present and discuss structural, magnetic and transport properties of the new ternary cage compound Ce4Pd12Sn25. The isostructural Pt analogue, Ce4Pt12Sn25 has previously been characterized as a metallic Kondo lattice system with a very low Kondo temperature TK ~ 0.25 K and an antiferromagnetic ground state with a Neel temperature TN =0.19 K. In contrast to the expectations that the smaller unit cell volume of Ce4Pd12Sn25 compared to Ce4Pt12Sn25 will weaken the magnetism and tune the system closer to a magnetic instability, we found evidence for a phase transition at a higher temperature Tmag=0.265 K.
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Authors: Anna Bajorek, Grażyna Chełkowska, Artur Chrobak, Marzena Kwiecień Grudziecka
Abstract: All studied Gd1-xCexIn3 compounds crystallize in the cubic AuCu3 - type of crystal structure. The influence of Gd/Ce substitution is reflected in the linear increase of the unit cell parameter. The temperature dependence of the electrical resistivity ρ(T) strongly depends on the Ce content. For compounds with x≤0.2 a typical metallic behavior has been observed. In contrary, for Ce-rich compounds (x≥0.5) a characteristic Kondo-type behaviour has been noticed. The analysis of cerium XPS core level lines reveals the occurrence of possible Ce intermediate valence.
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Authors: Jan Fikáček, Jiří Prchal, Jan Prokleška, Ivana Císařová, Vladimír Sechovský
Abstract: We have synthesized CeRuSn single crystals and performed measurements of electrical resistivity and specific heat. At high temperatures, abrupt transitions were observed at 290 and 225 K in electrical resistivity during cooling. Both transitions are connected with a large temperature hysteresis. Low temperature properties are dominated by an antiferromagnetic transition at 2.9 K, which involves only half of cerium ions, leaving the rest of them non-magnetic. A significant magnetocrystalline anizotropy was revealed by application of external magnetic field.
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