On the Origin of the Structural Modulation in the Bi Cuprates As Derived from 3d-Metal Substituted Phases

1989 ◽  
Vol 156 ◽  
Author(s):  
J. M. Tarascon ◽  
Y. LePage ◽  
W. R. McKinnon ◽  
E. Tselepis ◽  
P. Barboux ◽  
...  
Keyword(s):  
Single Crystal ◽  
X Ray ◽  
Structural Modulation ◽  
Doping Mechanism ◽  
Perovskite Type ◽  
Extra Oxygen ◽  
Oxygen Atoms

ABSTRACTA substitution for Cu by a 3d-metal (Fe, Co, Mn) in the superconducting Bi phases (Bi2Sr2Can−1CunOy; n = 1,2 and 3) has led to the discovery of new phases. These 3d-metal substituted phases are non-superconducting and, in contrast to the Cu-based phases, they exhibit a structural modulation that is commensurate. Single crystal x-ray studies were performed on the Bi2Sr3Fe2Oy, Bi2Sr2CoOy and Bi2Sr2MnOy compounds. A result, in common, is that the modulation is caused by the periodic insertion of a row of oxygen atoms in the Bi layers and this results in a corrugated-like slab structure. The Bi-O layers can be described as composed of alternating rocksalt-type and oxygen deficient perovskite-type blocks. For the Fe (n=2) phase the Bi atoms form ribbons (chains) in the ab plane. This is in contrast to the n=1 Co or Mn phases for which a disorder at the oxygen position is observed. Although the extra oxygen in the Bi-O layer could account for the doping mechanism in the high Tc Bi-phases, cation non-stoichiometry may also beimportant.

Two Modifications of Hg5Re2O10

1995 ◽  
Vol 50 (9) ◽  
pp. 1335-1339 ◽  
Author(s):  
Marietta S. Schriewer-Pöttgen ◽  
Wolfgang Jeitschko
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Elemental Mercury ◽  
Oxidation States ◽  
X Ray ◽  
Structure Factors ◽  
Oxygen Atoms

AbstractThe previously reported mercury perrhenate Hg5Re2O10, prepared hydrothermally, has now been obtained by reaction of HgO with the mercury(II) metaperrhenate Hg(ReO4)2 in sealed silica tubes. A second modification of this compound can be obtained by reaction of elemental mercury with Hg(ReO 4)2 also in sealed silica tubes. Its crystal structure has been determined from single-crystal X-ray data: P21/c, a - 861.5(1), b = 1200.9(2), c = 1203.9(2) pm, β = 97.15(1)°, Z = 4, R = 0.024 for 1733 structure factors and 105 variables. Both modifications may be represented by the formula Hg2+-2Hg2O - 2ReO4-, indicating that mercury occurs in oxidation states I and II. In both modifications the mercury and some oxygen atoms form two-dimensionally infinte, puckered, cationic nets of the composition (Hg2+-2Hg2O)n , which are separated by the ReO4- tetrahedra. In the modification reported earlier the mercury oxygen nets consist of condensed 16-membered rings, while the nets of the present modification contain 10- and 22-membered rings.

N–O Bond Cleavage During the Deprotonation of N,O-Bis(trimethylsilyl)hydroxylamine

2008 ◽  
Vol 63 (3) ◽  
pp. 339-341 ◽  
Author(s):  
Ajay Venugopal ◽  
Alexander Willner ◽  
Norbert W. Mitzel
Keyword(s):  
Solid State ◽  
Single Crystal ◽  
Elemental Analysis ◽  
Bond Cleavage ◽  
State Structure ◽  
X Ray Diffraction ◽  
Solid State Structure ◽  
X Ray ◽  
Potassium Hydride ◽  
Oxygen Atoms

The reaction of N,O-bis(trimethylsilyl)hydroxylamine with potassium hydride in pentane affords a product of the formula {K6[OSiMe3]4[ON(SiMe3)2]2}, resulting from deprotonation followed by N-O bond cleavage and 1,2-silylshift. The compound was characterised by elemental analysis and by single crystal X-ray diffraction. The aggregate consists of a K3O3 bis-cubane core, with N(SiMe3)2 groups at the oxygen atoms shared by the two cubes, andMe3Si groups attached to the four O vertices. Two weak K···N interactions are also detected in the solid state structure.

X-Ray Measurement of the Static Lattice Distortion in the Solid Solution of Oxygen in Titanium*

1962 ◽  
Vol 6 ◽  
pp. 136-141
Author(s):  
F. R. L. Schoening ◽  
F. Witt
Keyword(s):  
Single Crystal ◽  
Oxygen Concentration ◽  
Waller Factor ◽  
Interstitial Oxygen ◽  
Exponential Factor ◽  
X Ray ◽  
X Ray Scattering ◽  
Lattice Strains ◽  
Debye Waller Factor ◽  
Oxygen Atoms

AbstractOxygen was introduced into a single crystal of titanium in successive stages. The intensities of the h00 and 00l reflections were measured with a single-crystal diffractometer. The observed variation of the intensities with oxygen concentration was attributed to three factors: (1) the additional scattering from the oxygen atoms, (2) a change in the Debye-Waller factor, and (3) an exponential factor originating from the distortion around the oxygen atom. The theory of X-ray scattering from crystals containing centers of distortion was applied to the hexagonal titanium containing interstitial oxygen atoms. Using the variation of the lattice constant with oxygen concentration, it was possible to predict the intensity reduction due to lattice strains. It was concluded that it would have been possible to obtain an estimate of the defect concentration from the X-ray measurements of lattice expansion and intensity reduction.

scholarly journals Zur Besetzung von Oktaederund Tetraederpositionen in Bi2Ca2Fe2O9 / About Occupation of Octahedral- and Tetrahedral Positions of Bi2Ga2Fe2O9

1978 ◽  
Vol 33 (6) ◽  
pp. 669-670 ◽  
Author(s):  
Hk. Müller-Buschbaum ◽  
D. Chales de Beaulieu
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Laser Technique ◽  
Positive Evidence ◽  
X Ray ◽  
Oxygen Atoms

Abstract Single crystals of Bi2Ga4O9 and Bi2Ga2Fe2O9 were prepared by CO2-Laser technique and analysed by X-ray single crystal methods. Bi2Ga4O9 is one of the rare examples containing Ga3+ in octahedral as well as tetrahedral surrounding of oxygen. In Bi2Ga2Fe2O9 the coordination of oxygen atoms around Ga3+ is exclusively tetrahedral. Thus this compound represents positive evidence of the preferential occupation of tetrahedral holes by gallium

Crystal structure of Bis(O-ethylxanthato)bis(quinolin-8-olato)tin(IV)

1978 ◽  
Vol 31 (12) ◽  
pp. 2641 ◽  
Author(s):  
CL Raston ◽  
AH White ◽  
G Winter
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Least Squares ◽  
Coordination Sphere ◽  
Title Compound ◽  
Point Symmetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxygen Atoms

The crystal structure of the title compound, [Sn(S2COEt)2(C9H6NO)2], has been determined by single-crystal X-ray diffraction at 298 K and refined by least squares to a residual of 0.049 for 1771 ?observed? reflections. Crystals are monoclinic, P21/n, a 12.21(1), b 24.33(1), c 9.159(7) Ǻ, β 102.12(6)°, Z 4. The environment of the tin atom is six- coordinate: the two coordinating sulfur atoms of the monodentate xanthate ligands lie cis in the coordination sphere [Sn-S, 2.484(4), 2.510(4) Ǻ], and one in turn trans to the two oxine nitrogen atoms [Sn- N, 2.260(8), 2.237(10) Ǻ]. The remaining positions, trans to each other, are occupied by the oxine oxygen atoms [Sn-O, 2.047(7), 2.065(8) Ǻ]. O-Sn-O is 157.0(3)°. The overall point symmetry of the molecule is a good approximation to 2.

scholarly journals Crystal structure of Tetraaqua(ethylenediamine)nickel(II) sulfate dihydrate and of Tetraaqua(2,2'-bipyridyl)nickel(II) sulfate dihydrate

1984 ◽  
Vol 37 (5) ◽  
pp. 921 ◽  
Author(s):  
PC Healy ◽  
JM Patrick ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Water Molecule ◽  
Single Crystal ◽  
Least Squares ◽  
Crystal Structures ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
X Ray ◽  
Oxygen Atoms

The crystal structures of the title compounds, [Ni(OH2)4(en)] [SO4].2H2O, (1), and [Ni(OH2)4(bpy)]- [SO4].2H2O, (2), have been determined by single-crystal X-ray diffraction methods at 295 K, being refined by full matrix least-squares methods to residuals of 0.028,0.031 for 1852, 4323 independent 'observed' reflections respectively. Crystals of (1) are monoclinic, C2/c, a 9.459(4), b 12.192(7), c 12.294(3) �, β 119.84(4)�, Z 4. In the cation, Ni-N is 2.061(2) �; Ni-O (trans to O, N respectively) are 2.106(2), 2.063(2) �. Instead of being enlarged above 90� as predicted from repulsion theory, the angle between the pair of oxygen atoms trans to nitrogen is diminished, being 87 14(7)�. Crystals of (2) are triclinic, P1, a 11.476(5), b 9.351(5), c 7.793(4) �, α 77.63(4), β 83.52(3), γ87.40(4)�, Z 2. In the cation, Ni-N are both 2.063(2) �. Ni-O (trans to N, O respectively) are 2.060(2), 2.O42(2); 2.O80(2), 2�. The short Ni-O distance [2.042(2)�] is associated with the coordination of a trigonal water molecule.

Variable-temperature single-crystal X-ray diffraction study of tetragonal and cubic perovskite-type barium titanate phases

2016 ◽  
Vol 72 (1) ◽  
pp. 151-159 ◽  
Author(s):  
Tomotaka Nakatani ◽  
Akira Yoshiasa ◽  
Akihiko Nakatsuka ◽  
Tatsuya Hiratoko ◽  
Tsutomu Mashimo ◽  
...  
Keyword(s):  
Single Crystal ◽  
Diffraction Study ◽  
Variable Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
M Phase ◽  
The Mean ◽  
Perovskite Type

A variable-temperature single-crystal X-ray diffraction study of a synthetic BaTiO3perovskite has been performed over the temperature range 298–778 K. A transition from a tetragonal (P4mm) to a cubic (Pm \overline 3 m) phase has been revealed near 413 K. In the non-centrosymmetricP4mmsymmetry group, both Ti and O atoms are displaced along thec-axis in opposite directions with regard to the Ba position fixed at the origin, so that Ti4+and Ba2+cations occupy off-center positions in the TiO6and BaO12polyhedra, respectively. Smooth temperature-dependent changes of the atomic coordinates become discontinuous with the phase transition. Our observations imply that the cations remain off-center even in the high-temperature cubic phase. The temperature dependence of the mean-square displacements of Ti in the cubic phase includes a significant static component which means that Ti atoms are statistically distributed in the off-center positions.

Structural Modulation and Phase Transitions in La2CoO4.14 Investigated by Synchrotron X-ray and Neutron Single-Crystal Diffraction

2012 ◽  
Vol 51 (18) ◽  
pp. 9789-9798 ◽  
Author(s):  
Loïc Le Dréau ◽  
Carmelo Prestipino ◽  
Olivier Hernandez ◽  
Jürg Schefer ◽  
Gavin Vaughan ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Single Crystal ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Structural Modulation

scholarly journals Formation of Unsymmetrical Trinuclear Metallamacrocycles Based on Two Different Cone Calix[4]arene Macrocyclic Rings

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 364 ◽  
Author(s):  
Mariia V. Kniazeva ◽  
Alexander S. Ovsyannikov ◽  
Daut R. Islamov ◽  
Aida I. Samigullina ◽  
Aidar T. Gubaidullin ◽  
...  
Keyword(s):  
Single Crystal ◽  
Coordination Compounds ◽  
Metallic Cluster ◽  
X Ray Diffraction ◽  
X Ray ◽  
Recognition Pattern ◽  
Carboxylate Groups ◽  
Different Types ◽  
Solvent Molecules ◽  
Oxygen Atoms

A combination of tetrasulfonylcalix[4]arene (3-4H) together with a calix[4]arene dicarboxylate derivative 2-4H led, in the presence of MII(NO3)2 (M = Co, Ni, Zn), to the formation of three novel isostructural metallomacrocycles of formula [M3(DMF)2(μ3-H2O)-(2-2H)-3]. The structure of the prepared coordination compounds was studied in the solid state using single crystal/powder X-ray diffraction studies. The X-ray diffraction on single crystal revealed that the structure of the obtained supramolecular complexes is composed of a trinuclear metallic cluster [M3]+6 held between one di-deprotonated molecule of (2-2H)2− offering two carboxylate groups for binding metal cations and one tetra-deprotonated compound 34−, where four oxygen atoms, belonging to four deprotonated phenolic moieties and three oxygen atoms coming from three SO2 groups, are coordinated with the cluster core. Thus, an example of an easily reproducible molecular recognition pattern involving two different types of calix[4]arene based ligands, displaying different coordination moieties, and trinuclear metallic clusters, is reported here. In addition, it has been shown that the cone moieties of the calixarene also encapsulate solvent molecules.

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