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The phase diagram of the Yb-Ge system
No full textThe phase diagram of the Yb-Ge system was investigated over the whole compositional range by means of differential thermal analysis (DTA), X-ray diffraction (XRD), optical microscopy (LOM) and electron probe microanalysis (EMPA). Besides the already known intermediate phases Yb2Ge (PbCl2-type), Yb5Ge3 (Mn5Si 3-type), Yb11Ge10 (Ho11Ge 10-type) and Yb3Ge5 (Th3Pd 5-type), two new compounds have been found: Yb5Ge 4 (Sm5Ge4-type) and Yb3Ge 8, which crystallize with a new triclinic structure type. All the compounds formed in the system have been completely structurally characterized by single crystal determinations. © 2003 Elsevier B.V. All rights reserved
The phase diagram of the Ba-Ge system
No full textThe phasediagram of the Ba–Gesystem has been revised, in the composition range 0–75 at.% Ge, from a thermal point of view, resulting substantially different from that previously reported in Massalski collection. The existence and composition of the following compounds are confirmed: Ba2Ge, Ba5Ge3, BaGe, dimorphic Ba3Ge4, BaGe2, Ba6Ge25 and Ba8Ge43. Save for Ba2Ge, BaGe and BaGe2, forming congruently, all other phases melt incongruently. Four eutectic points occur at 7.5, 42.5, 56.0 and 82.5 at.% Ge, respectively
The phase diagram of the Sr-Ge system
No full textThe phase diagram of the Sr–Ge system has been investigated across almost the whole composition range (0–85 at.% Ge) using differential thermal analysis and X-ray diffraction. Four intermediate phases exist: Sr2Ge (PbCl2-type, orthorhombic oP12-Pnma), Sr5Ge3 (Cr5B3-type, tetragonal tI32-I4/mcm), SrGe (CrB-type, orthorhombic oC8-Cmcm) and SrGe2 (BaSi2-type, orthorhombic oP24-Pnma). A further intermediate phase, observed only at high temperature above 985 °C, crystallizes with a defective AlB2-type structure. Four eutectics occur in the system: about 5 at.% Ge at 740 °C, 42 at.% Ge at 1100 °C, 61 at.% Ge at 965 °C and 85 at.% Ge at 755 °C. As a whole, the Sr–Gesystem appears very similar to the Sr–Si one
The phase diagram of the Ba-Si system
No full textThe phase diagram of the Ba-Si system has been completely revised from a thermal point of view. All the already-known intermediate phases have been confirmed: Ba2Si (Co2Si type), Ba5Si3 (Ba5Si3 type), BaSi (CrB type), Ba3Si4 (Ba3Si4 type) and BaSi2 (BaSi2 type). Save for Ba5Si3, which forms peritectically, all other compounds melt congruently. The five eutectic compositions occurring in the system are at 11, 40, 52.5, 60 and 83 at.% Si, respectively
Examples of linear structures of intermetallic compounds described as intergrowth of segments of simple basic structures
No full textSegments of the basic structures BaAl4, AlB2, W, Po, Cu3Au, CaF2 or hybrids obtained combining two segments of these types are used with the mechanism of intergrowth to describe nine linear structures of binary and ternary intermetallic compounds formed by rare earth or alkaline earth metals. Such a representation allows to display relationship among the structures. All examined compounds with one exception contain AlB2 fragments, that means rare earth or alkaline earth face-sharing trigonal prisms centred by the small atoms. Depending on the segments between which the AlB2 fragment is comprised, the atoms centring the prisms show a different behaviour in their waist contacts
Ca28Ga11, a structure with three types of coordination polyedra around the Gallium atoms
No full textIr: Isotypic Compounds with a New Structure Type.
No full textThe synthesis and the crystal structure of two new intermetallic phases with formula Ca5Rh and Ca5Ir are reported. The two compounds are isotypic and crystallize with anewstructuretype. The crystal structure, elucidated by single-crystal X-ray techniques for the iridium compound and confirmed for Ca5Rh by powder data, is orthorhombic, oP24-Pnma, Z = 4. The lattice constants, as obtained from Guinier powder patterns are: a = 7.655(3) Å, b = 15.878(6) Å and c = 6.786(2) Å for Ca5Ir and a = 7.569(3) Å, b = 16.067(10) Å and c = 6.725(3) Å for Ca5Rh.
Apart for the 9:1 phase found in several M–X systems (M = Ca, Sr, Eu; X = Rh, Ir, Pd, Pt), whose structure, however, has not yet been solved, the 5:1 composition represents the M-richest composition so far observed in such systems
Crystal structure of ytterbium gold plumbide (2/2/1), Yb2Au2Pb
No full textAu2PbYb2, tetragonal, P42/mnm (No. 136), a = 8.037(2) Å, c = 7.465(2) Å, V = 482.2 Å3, Z = 4, Rgt(F) = 0.036, wRobs(F2) = 0.069, T=293 K
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