Crystal Structure of the Ternary Compound Sc6Cu24.1Al11.9

2016 ◽  
Vol 257 ◽  
pp. 26-29 ◽  
Author(s):  
Nastasia Klymentiy ◽  
Nataliya Semuso ◽  
Svitlana Pukas ◽  
Yaroslav O. Tokaychuk ◽  
Lev Akselrud ◽  
...  

The crystal structure of a new ternary aluminide of refined composition Sc6Cu24.1(2)Al11.9(2) was solved by direct methods from X-ray powder diffraction data. It belongs to the cubic space group Im-3, Pearson symbol cI176-8, a = 13.5337(5) Å. The structure of Sc6Cu24.1Al11.9 may be described as a packing of 16-vertex coordination polyhedra of the Sc atoms, which form icosahedral clusters around the origin and the center of the body-centered unit cell. The voids at the centers of the clusters are filled by Cu4 tetrahedra, disordered between two possible orientations. The structure is closely related to the structure types Ru3Be17 and Ce6Au27.6Sn6.8.

2016 ◽  
Vol 72 (8) ◽  
pp. 1159-1162 ◽  
Author(s):  
Alagappa Rammohan ◽  
James A. Kaduk

The crystal structure of anhydrous tripotassium citrate, [K3(C6H5O7)]n, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The three unique potassium cations are 6-, 8-, and 6-coordinate (all irregular). The [KOn] coordination polyhedra share edges and corners to form a three-dimensional framework, with channels running parallel to thecaxis. The only hydrogen bond is an intramolecular one involving the hydroxy group and the central carboxylate group, with graph-set motifS(5).


Author(s):  
Alagappa Rammohan ◽  
James A. Kaduk

The crystal structure of trirubidium citrate, 3Rb+·C6H5O73−, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The two independent Rb+cations are seven- and eight-coordinate, with bond-valence sums of 0.99 and 0.92 valence units. The coordination polyhedra share edges and corners to form a three-dimensional framework. The only hydrogen bond is an intramolecular one between the hydroxy group and the central carboxylate, with graph setS(5). The hydrophobic methylene groups lie in pockets in the framework.


2019 ◽  
Vol 289 ◽  
pp. 108-113
Author(s):  
Romana Iryna Martyniak ◽  
Nataliya Muts ◽  
Olga Sichevych ◽  
Horst Borrmann ◽  
Matej Bobnar ◽  
...  

The crystal structure of the (Cr,Ni)4Si phase with and without Co was refined from X-ray powder diffraction data. The compound crystallises with an Au4Al-type structure (Pearson symbol cP20, space group P213): unit-cell parameter a = 0.611959(6) nm for the composition (Cr0.312Ni0.688)4Si, a = 0.612094(6) nm for (Cr0.375Ni0.625)4Si, and a = 0.612316(6) nm for (Cr0.337Co0.063Ni0.600)4Si. The magnetic susceptibility was measured in external fields up to 7 T at temperatures between 1.8 and 400 K. The three investigated samples exhibited paramagnetic behaviour described by the modified Curie-Weiss law: χ0 = 146∙10-6 emu g-at.-1, μeff = 0.21 μB/atom, θP = -13 K for (Cr0.312Ni0.688)4Si; χ0 = 158∙10-6 emu g-at.-1, μeff = 0.20 μB/atom, θP = -15 K for (Cr0.375Ni0.625)4Si; χ0 = 169∙10-6 emu g-at.-1, μeff = 0.18 μB/atom, θP = -52 K for (Cr0.337Co0.063Ni0.600)4Si.


2014 ◽  
Vol 950 ◽  
pp. 53-56
Author(s):  
Bin He ◽  
Ming Qin ◽  
Liu Qing Liang ◽  
Zhao Lu ◽  
De Gui Li ◽  
...  

Crystal structure and X-ray powder diffraction data for the Al7Cu5Y ternary compound are presented. The compound crystallizes in the body-centered tetragonal with the Al7Fe5Y structure type (space group I4/mmm), the lattice parameters a = 8.6960(9) Å, c = 5.1256(7) Å, V =387.62 Å3, Z =2, ڑx =5.102 g/cm3, F30 = 275.5(0.0033, 33) and RIR =1.23.


Author(s):  
Alagappa Rammohan ◽  
James A. Kaduk

The crystal structure of caesium dihydrogen citrate, Cs+·H2C6H5O7−, has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The coordination polyhedra of the nine-coordinate Cs+cations share edges to form chains along thea-axis. These chains are linked by corners along thec-axis. The un-ionized carboxylic acid groups form two different types of hydrogen bonds; one forms a helical chain along thec-axis, and the other is discrete. The hydroxy group participates in both intra- and intermolecular hydrogen bonds.


2006 ◽  
Vol 21 (3) ◽  
pp. 220-224
Author(s):  
Koichiro Fukuda ◽  
Hajime Hasegawa ◽  
Tomoyuki Iwata ◽  
Shinobu Hashimoto

Crystal structure of Ca1.1Co1.9(PO4)2 was successfully determined from laboratory X-ray powder diffraction data (Co Kα) using direct methods and the Rietveld refinement. The crystal structure was found to be monoclinic (space group P21∕n, Z=4) with lattice dimensions of a=1.452 67(5) nm, b=0.494 34(1) nm, c=0.867 50(3) nm, β=92.316(1)°, and V=0.622 45(3) nm3. The final reliability indices calculated from the Rietveld refinement were Rwp=3.93%, Rp=3.02%, RB=4.10%, and S=1.48. Both Co and Ca atoms were distributed over the 2a and 2d sites with a preference of Ca at the 2d site. The coexistence of Co and Ca on the 2a and 2d sites is indispensable for stabilizing Ca1.1Co1.9(PO4)2 in the Ca3(PO4)2-Co3(PO4)2 system.


2010 ◽  
Vol 25 (3) ◽  
pp. 247-252 ◽  
Author(s):  
F. Laufek ◽  
J. Návrátil

The crystal structure of skutterudite-related phase IrGe1.5Se1.5 has been refined by the Rietveld method from laboratory X-ray powder diffraction data. Refined crystallographic data for IrGe1.5Se1.5 are a=12.0890(2) Å, c=14.8796(3) Å, V=1883.23(6) Å3, space group R3 (No. 148), Z=24, and Dc=8.87 g/cm3. Its crystal structure can be derived from the ideal skutterudite structure (CoAs3), where Se and Ge atoms are ordered in layers perpendicular to the [111] direction of the original skutterudite cell. Weak distortions of the anion and cation sublattices were also observed.


2016 ◽  
Vol 31 (4) ◽  
pp. 292-294 ◽  
Author(s):  
V. D. Zhuravlev ◽  
A. P. Tyutyunnik ◽  
N. I. Lobachevskaya

A polycrystalline sample of Ca4ZrGe3O12 was synthesized using the nitrate–citrate method and heated at 850–1100 °C. Structural refinement based on X-ray powder diffraction data showed that the crystal structure is of the garnet type with a cubic unit-cell parameter [a = 12.71299(3) Å] and the space group Ia$\bar 3$d. The structural formula is presented as Ca3[CaZr]octa[Ge]tetraO12.


Author(s):  
Andrew J. Cigler ◽  
James A. Kaduk

The crystal structure of poly[μ-citrato-dilithium(I)potassium(I)], [Li2K(C6H5O7)] n , has been solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The citrate anion triply chelates to the K+ cation through the hydroxyl group, the central carboxylate, and the terminal carboxylate. The KO7 coordination polyhedra share edges, forming chains parallel to the a axis. These chains share edges with one tetrahedral Li ion, and are bridged by edge-sharing pairs of the second tetrahedral Li ion, forming layers parallel to the ac plane.


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