scholarly journals A new Rubidium - Bismuth polyphosphate RbBi(PO3)4: Growth, X-ray single crystal and vibrational study

2014 ◽  
Vol 10 (7) ◽  
pp. 2881-2893
Author(s):  
Khaled JAOUADI ◽  
Tahar MHIRI ◽  
Nabil ZOUARI

Solid-solution studies in the ternary Rb2O – Bi2O3 – P2O5 system, carried out in a search for inorganic materials have a considerable interest mainly for their optical properties, specifically in laser technology, yielded the new compound RbBi(PO3)4. Single-crystal X-ray measurement revealed that RbBi(PO3)4 crystallizes in space group P21/c with a structural type IV and has lattice parameters a = 10.430, b = 8.984, c = 12.967 Å,  = 126.1°, Z = 4 and V = 981.6 Å3. The all eighteen atoms were located in the asymmetric unit. Refinement using anisotropic temperature factors for all atoms yielded weighted residuals based on F and F2 values, respectively, of R1 = 0.0131 and WR2 = 0.0252 for all observed reflections. The atomic arrangement can be described as a long chain polyphosphate organization, helical ribbons (PO3)n. Two types of infinite chains, with a period of eight PO4 tetrahedra run along the longest unit-cell directions. Infrared and Raman spectra at room temperature, were investigated, show clearly some characteristics bands of infinite chains structure of PO4 tetrahedra linked by a bridge oxygen.

1966 ◽  
Vol 44 (8) ◽  
pp. 939-943 ◽  
Author(s):  
A. K. Das ◽  
I. D. Brown

(NH4)2TeBr6 and Cs2TeBr6 crystals have the cubic K2PtCl6 structure with space group: [Formula: see text] with a0 = 10.728 ± 0.003 Å and 10.918 ± 0.002 Å respectively. The positional coordinate of the bromine atom, and the anisotropic temperature factors of all atoms in the unit cell, have been refined for both crystals by a full matrix least-squares analysis of the three dimensional X-ray diffraction data (R = 0.08). The Te—Br distance, corrected for probable thermal motions of atoms forming the bond, is 2.70 ± 0.01 Å in both crystals.


2012 ◽  
Vol 68 (6) ◽  
pp. 602-609 ◽  
Author(s):  
Anatoly A. Udovenko ◽  
Natalia M. Laptash

Five isomorphous d 0 transition metal oxofluoride compounds A 3[M 2O x F11 − x ]·(AF)0.333 (A = K, Rb, NH4; M = Nb, Mo, W; x = 2, 4) have been synthesized from acid fluoride solutions, and their crystal structures have been determined by single-crystal X-ray diffraction. The basic structural building units are dinuclear M 2 X 11 (dimers) formed from NbOF5 or Mo(W)O2F4 octahedra connected by the fluorine bridging atom. In the Nb2O2F9 dimer, the O atoms occupy apical corners. In the M 2O4F7 (M = Mo, W) dimers two O atoms are also apically placed, whereas the other two O atoms are statistically disordered in equatorial planes. The arrangement of dimers is so that the hexagonal tunnels containing `free' fluoride ions are formed. During the irradiation process the orthorhombic structure of K3Nb2O2F9·(KF)0.333 transforms into a pseudo-trigonal one with a = 23.15 Å, which is the [101] diagonal of the orthorhombic unit cell. The other four trigonal crystals are merohedral twins.


1997 ◽  
Vol 62 (8) ◽  
pp. 1239-1253 ◽  
Author(s):  
Jonathan Bould ◽  
Paul Brint ◽  
John D. Kennedy ◽  
Mark Thornton-Pett ◽  
Lawrence Barton ◽  
...  

[6-(CO)-6-H-6,9-(PPh3)2-6P,5C-μ-(2-Ph2PC6H4)-arachno-6-IrB9H11] (1) results from the reaction of [6-H-6-(PPh3)-6P,5C-μ-(2-Ph2PC6H4)-nido-6-IrB9H12] (2) with carbon monoxide in refluxing benzene. It is characterised by NMR spectroscopy and by single-crystal X-ray diffraction analysis. Crystals were triclinic, space group P1, with a = 10.688(2), b = 13.114(3), c = 22.356(5) Å, α = 78.33(2), β = 89.482(10), γ = 70.884(12)°, and Z = 2. The compound is of the little-examined arachno ten-vertex metallaborane structural type. A second compound of this type, [6-(CO)-6-H-6,6-(PMe2Ph)2-9-(PPh3)-arachno-6-IrB9H11] (3), isolated from a reaction system involving [Ir(CO)Cl(PPh3)2], PMe2Ph and the [nido-B9H12]- anion, has also been characterised crystallographically. Crystals were triclinic, space group P1, with a = 10.389(1), b = 10.511(1), c = 19.699(3) Å, α = 75.03(1), β = 85.53(1), γ = 74.88(1)°, and Z = 2.


2012 ◽  
Vol 65 (7) ◽  
pp. 823 ◽  
Author(s):  
Karen D. M. MaGee ◽  
Guy Travers ◽  
Brian W. Skelton ◽  
Massimilliano Massi ◽  
Alan D. Payne ◽  
...  

N-Heterocyclic carbene–nickel complexes with five- and four-coordinate geometries [(CNC)NiBr2] and [(CNC)NiBr]X (X = PF6 or BPh4) have been prepared with the pincer ligands 2,6-bis(N-octylbenzimidazolin-2-ylidene)pyridine and 2,6-bis(N-butyl-5,6-dimethoxybenzimidazolin-2-ylidene)pyridine. The addition of the n-octyl substituent significantly extends the solubility of the complexes and has allowed UV-vis solution studies of the complexes in dichloromethane and methanol. The four- and five-coordinate species exist in equilibrium in solution and this equilibrium has been explored by UV-vis studies. The complexes have also been characterized by NMR studies, and single crystal X-ray diffraction studies have been performed on [(CNC)NiBr2] (where CNC = 2,6-bis(N-octylbenzimidazolin-2-ylidene)pyridine) and [(CNC)NiBr]BPh4 (where CNC = 2,6-bis(N-butyl-5,6-dimethoxybenzimidazolin-2-ylidene)pyridine).


Author(s):  
María Ana Pérez-Cruz ◽  
María de la Paz Elizalde-González ◽  
Roberto Escudero ◽  
Sylvain Bernès ◽  
Rutilo Silva-González ◽  
...  

A natural single crystal of the ferrimagnetic oxide FeCrO3, which was found in an opencast mine situated in the San Luis Potosí State in Mexico, has been characterized in order to elucidate some outstanding issues about the actual structure of this material. The single-crystal X-ray analysis unambiguously shows that transition metal cations are segregated in alternating layers normal to the threefold crystallographic axis, affording a structure isomorphous to that of ilmenite (FeTiO3), in the space group R \overline{3}. The possible occurrence of cation antisite and vacancy defects is below the limit of detection available from X-ray data. Structural and magnetic results are in agreement with the coherent slow intergrowth of magnetic phases provided by the two antiferromagnetic corundum-type parent oxides Fe2O3(hematite) and Cr2O3(eskolaite). Our results are consistent with the most recent density functional theory (DFT) studies carried out on digital FeCrO3[Sadat Nabi & Pentcheva (2011).Phys. Rev. B,83, 214424], and suggest that synthetic samples of FeCrO3might present a cation distribution different to that of the ilmenite structural type.


2017 ◽  
Vol 458 ◽  
pp. 84-96 ◽  
Author(s):  
Mina Shahbazi ◽  
Farzaneh Mehrzad ◽  
Masoud Mirzaei ◽  
Hossein Eshtiagh-Hosseini ◽  
Joel T. Mague ◽  
...  

Author(s):  
Oleh Stetsiuk ◽  
Patricia Bolle ◽  
Marie Cordier ◽  
Julien Boixel ◽  
Rémi Dessapt

Five new highly photochromic hybrid organic-inorganic materials were successfully prepared by supramolecular assembly of normal (1+) and mixed (2+) cationic dithienylethenes (DTEs) and polyoxometalates (POMs) units. Single-crystal X-ray diffraction studies...


1999 ◽  
Vol 55 (6) ◽  
pp. 937-946 ◽  
Author(s):  
Calum R. I. Chisholm ◽  
Sossina M. Haile

Ongoing studies of the CsHSO4–CsH2PO4 system, aimed at developing novel proton conducting solids, resulted in the new compound Cs2(HSO4)(H2PO4) (dicesium hydrogensulfate dihydrogenphosphate). Single-crystal X-ray diffraction (performed at room temperature) revealed Cs2(HSO4)(H2PO4) to crystallize in space group P21/n with lattice parameters a = 7.856 (8), b = 7.732 (7), c = 7.827 (7) Å, and β = 99.92 (4)°. The compound has a unit-cell volume of 468.3 (8) Å3 and two formula units per cell, giving a calculated density of 3.261 Mg m−3. Six non-H atoms and two H atoms were located in the asymmetric unit, with SO4 and PO4 groups randomly arranged on the single tetrahedral anion site. Refinement using all observed reflections yielded weighted residuals of 0.0890 and 0.0399 based on F 2 and F values, respectively. Anisotropic temperature factors were employed for all six non-H atoms and fixed isotropic temperature factors for the two H atoms. The structure contains zigzag chains of hydrogen-bonded anion tetrahedra that extend in the [010] direction. Each tetrahedron is additionally linked to a tetrahedron in a neighboring chain to give a planar structure with hydrogen-bonded sheets lying parallel to (1¯01). Thermal analysis of the superprotonic transition in Cs2(HSO4)(H2PO4) showed that the transformation to the high-temperature phase occurs by a two-step process. The first is a sharp transition at 334 K and the second a gradual transition from 342 to 378 K. The heat of transformation for the entire process (∼330–382 K) is 44 ± 2 J g−1. Thermal decomposition of Cs2(HSO4)(H2PO4) takes place at much higher temperatures, with an onset of approximately 460 K.


Author(s):  
G. Nover ◽  
G. Will

AbstractMg/Fe order in olivine has been determined by X-ray diffraction data, for example by Wenk and Raymond (1973). We have now studied the dependence of the Mg/Fe order vs. oxygen partial pressure. Two natural olivine samples of volcanic origin containing respectively 10 and 12 % fayalite were selected. The atomic positions, anisotropic temperature factors, extinction coefficient and site occupancies have been refined toThese experiments seem to indicate that the prevailing oxygen partial pressure determines the different Mg/Fe order found in natural olivine crystals.


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