scholarly journals Dynamic Disorder of Fe3+ Ions in the Crystal Structure of Natural Barioferrite

Minerals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 340 ◽  
Author(s):  
Arkadiusz Krzątała ◽  
Taras Panikorovskii ◽  
Irina Galuskina ◽  
Evgeny Galuskin
Keyword(s):  
Crystal Structure ◽  
Electron Probe ◽  
Barium Ferrite ◽  
Stacking Sequence ◽  
Dynamic Disorder ◽  
X Ray ◽  
Bond Lengths ◽  
Trigonal Bipyramidal ◽  
Equatorial Bond ◽  
The Mean

A natural barioferrite, BaFe3+12O19, from a larnite–schorlomite–gehlenite vein of paralava within gehlenite hornfels of the Hatrurim Complex at Har Parsa, Negev Desert, Israel, was investigated by Raman spectroscopy, electron probe microanalysis, and single-crystal X-ray analyses acquired over the temperature range of 100–400 K. The crystals are up to 0.3 mm × 0.1 mm in size and form intergrowths with hematite, magnesioferrite, khesinite, and harmunite. The empirical formula of the barioferrite investigated is as follows: (Ba0.85Ca0.12Sr0.03)∑1(Fe3+10.72Al0.46Ti4+0.41Mg0.15Cu2+0.09Ca0.08Zn0.04Mn2+0.03Si0.01)∑11.99O19. The strongest bands in the Raman spectrum are as follows: 712, 682, 617, 515, 406, and 328 cm−1. The structure of natural barioferrite (P63/mmc, a = 5.8901(2) Å, c = 23.1235(6) Å, V = 694.75(4) Å3, Z = 2) is identical with the structure of synthetic barium ferrite and can be described as an interstratification of two fundamental blocks: spinel-like S-modules with a cubic stacking sequence and R-modules that have hexagonal stacking. The displacement ellipsoids of the trigonal bipyramidal site show elongation along the [001] direction during heating. As a function of temperature, the mean apical Fe–O bond lengths increase, whereas the equatorial bond lengths decrease, which indicates dynamic disorder at the Fe2 site.

scholarly journals Darstellung und Kristallstruktur von K2Sn2S5 und K2Sn2Se5 / Preparation and Crystal Structure of K2Sn2S5 and K2Sn2Se5

1992 ◽  
Vol 47 (2) ◽  
pp. 197-200 ◽  
Author(s):  
Kurt O. Klepp
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structure Type ◽  
Slow Cooling ◽  
Bond Lengths ◽  
Trigonal Bipyramidal ◽  
Equatorial Bond ◽  
Binary Compounds ◽  
R Factors ◽  
Distorted Trigonal Bipyramidal

K2Sn2S5 and K2Sn2Se5 were prepared by reacting stoichiometric powdered mixtures of the binary compounds K2S or K2Se with Sn and the corresponding chalcogen at 1070 K, followed by slow cooling of the melt. The two compounds are isostructural and crystallize with the Tl2Sn2S5 structure type, s.g. C 2/c, Z = 4 with a = 11.072(5) Å, b = 7.806(3)Å, c = 11.517(5)Å, β = 108.43(2)° for K2Sn2S5 and a = 11.613(5)Å, b = 8.189(3) Å, c = 11,897(6) Å, β = 108.28(2)° for K2Sn2Se5. The crystal structures were refined to conventional R-factors of 0.032 and 0.031, respectively. Sn-atoms are in a distorted trigonal-bipyramidal chalcogen coordination. The average equatorial bond lengths are Sn -S: 2.427 Å and Sn -Se: 2.552 Å , the axial ones are Sn -S: 2.600 Å and Sn -Se: 2.774 Å.

Pyridin-Addukte von Cyclothiazeno-Vanadiumdichlorid Die Kristallstruktur von [VCl2(N3S2)(C5H5N)] / Pyridine Adducts of Cyclo-thiazeno Vanadium Dichloride The Crystal Structure of [VCl2(N3S2)(C5H5N)]

1985 ◽  
Vol 40 (12) ◽  
pp. 1631-1637 ◽  
Author(s):  
Ruth Christophersen ◽  
Paul Klingelhöfer ◽  
Ulrich Müller ◽  
Kurt Dehnicke
Keyword(s):  
Crystal Structure ◽  
Ir Spectra ◽  
Chlorine Atom ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Bond Lengths ◽  
Trigonal Bipyramidal ◽  
Independent Molecules

Abstract The pyridine complexes of cyclo-thiazeno vanadium dichloride, [VCl2(N3S2)py] and [VCl2(N3S2)(py)2] were synthesized by reactions of polymeric VCl2(N3S2) with varying amounts of pyridine in CH2Cl2. The compounds were characterized by their IR spectra as well as by their 51V NM R spectra. The crystal structure of [VCl2(N3S2)(C5H5N)] was determined by means of X-ray diffraction (1582 independent observed reflexions, R = 0.031). Crystal data: orthorhombic, space group Pnma, a = 1372, b - 2261, c - 1068 pm, Z = 12. In the lattice there are two monomeric, crystallographically independent molecules [VCl2(N3S2)(C5H5N)], which differ only slightly. The vanadium atoms have a trigonal bipyramidal coordination with the N atom of the pyridine molecule and one chlorine atom in apical positions, and with one chlorine atom and the N atoms of the cyclo-thiazeno ligand in equatorial positions. The VN bond lengths of the planar VN3S2 ring of 174 pm correspond to double bonds

The crystal structure of W(CO)5piperidine: Implications for photoreactivity of W(CO)5L complexes

1991 ◽  
Vol 69 (12) ◽  
pp. 2033-2037 ◽  
Author(s):  
Carol Moralejo ◽  
Cooper H. Langford ◽  
Peter H. Bird
Keyword(s):  
Crystal Structure ◽  
Bond Length ◽  
Key Words ◽  
Triplet Excitation ◽  
X Ray ◽  
Bond Lengths ◽  
Model Based ◽  
Equatorial Bond ◽  
Reverse Trend ◽  
Back Donation

The X-ray crystal structure of W(CO)5piperidine is reported and assignments are given for the LF and CT band of W(CO)5piperidine and W(CO)5pyridine. The [Formula: see text](axial), and [Formula: see text] (equatorial) bond lengths for W(CO)5pip are 2.330(5), 1,963(6), and 2.04(7), respectively. The longer [Formula: see text] bond length in W(CO)5pip compared to W(CO)5pyr corresponds to greater photoreactivity observed under LF triplet excitation for W(CO)5pip but cannot account for the reverse trend observed under LF singlet irradiation. The structure also fails to support a model based on differences in π back donation from W. It is concluded that differences between singlet and triplet photoreaction originate in the relative rates of radiationless decay. Key words: W(CO)5piperidine, photoreactivity, crystal structure.

Stereospecific reactions of aryltellurium(IV) trichlorides with 3-cyclohexene-1-methanol and 3-cyclohexene-1,1-dimethanol: the X-ray crystal structure of 2′,4′-dimethoxyphenyl(trans-6-oxabicyclo[3.2.1]oct-4-yl)tellurium(IV) dichloride

1995 ◽  
Vol 73 (2) ◽  
pp. 255-263 ◽  
Author(s):  
Bozena Borecka ◽  
T. Stanley Cameron ◽  
M. Azad Malik ◽  
Barry C. Smith
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Lone Pair ◽  
Monoclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Bond Lengths ◽  
Trigonal Bipyramidal ◽  
Compound C ◽  
Stereospecific Reactions

Aryltellurium(IV) trichlorides react with 3-cyclohexene-1-methanol and 3-cyclohexene-1,1-dimethanol to give aryl(trans-6-oxabicyclo[3.2.1]oct-4-yl)tellurium(IV) dichlorides and aryl(cis-1-hydroxymethyl-trans-6-oxabicyclo[3.2.1]oct-4-yl)tellurium(IV) dichlorides. The structure of 2′,4′-dimethoxyphenyl(trans-6-oxabicyclo[3.2.1]oct-4-yl)tellurium(IV) dichloride has been determined by single crystal X-ray analysis. The compound C15H20Cl2O3Te, Mr = 446.8, crystallizes in the monoclinic space group P21/c with a = 9.626(2) Å, b = 15.768(5) Å, c = 11.176(3) Å, β = 92.08(1)°, V = 1695.2(5) Å3 and D(calc) = 1.751 for Z = 4. Tellurium is bonded axially to two chlorines and equatorially to aryl carbon and carbon from the cyclohexyl portion of oxabicyclo[3.2.1]oct-4-yl in a pseudo-trigonal-bipyramidal arrangement having an equatorial lone pair of electrons. Bond lengths are Te—Cl(1) = 2.492(3) Å, Te—Cl(2) = 2.539(3) Å, Te—C(4) = 2.175(10) Å, and Te—C(9) = 2.090(10) Å. Keywords: organotellurium(IV), 3-cyclohexene-1-methanol, 3-cyclohexene-1, 1-dimethanol.

scholarly journals Crystal Structure Refinements of Four Monazite Samples from Different Localities

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1028 ◽  
Author(s):  
M. Mashrur Zaman ◽  
Sytle M. Antao
Keyword(s):  
Crystal Structure ◽  
Electron Probe ◽  
Unit Cell Volume ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Large Unit Cell ◽  
A Site

This study investigates the crystal chemistry of monazite (APO4, where A = Lanthanides = Ln, as well as Y, Th, U, Ca, and Pb) based on four samples from different localities using single-crystal X-ray diffraction and electron-probe microanalysis. The crystal structure of all four samples are well refined, as indicated by their refinement statistics. Relatively large unit-cell parameters (a = 6.7640(5), b = 6.9850(4), c = 6.4500(3) Å, β = 103.584(2)°, and V = 296.22(3) Å3) are obtained for a detrital monazite-Ce from Cox’s Bazar, Bangladesh. Sm-rich monazite from Gunnison County, Colorado, USA, has smaller unit-cell parameters (a = 6.7010(4), b = 6.9080(4), c = 6.4300(4) Å, β = 103.817(3)°, and V = 289.04(3) Å3). The a, b, and c unit-cell parameters vary linearly with the unit-cell volume, V. The change in the a parameter is large (0.2 Å) and is related to the type of cations occupying the A site. The average <A-O> distances vary linearly with V, whereas the average <P-O> distances are nearly constant because the PO4 group is a rigid tetrahedron.

scholarly journals Vibrational anisotropy of <i>δ</i>-(Al,Fe)OOH single crystals as probed by nuclear resonant inelastic X-ray scattering

2021 ◽  
Vol 33 (4) ◽  
pp. 485-502
Author(s):  
Johannes Buchen ◽  
Wolfgang Sturhahn ◽  
Takayuki Ishii ◽  
Jennifer M. Jackson
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Single Crystals ◽  
Vibrational Properties ◽  
Phonon Density ◽  
Phonon Density Of States ◽  
X Ray ◽  
X Ray Scattering ◽  
The Mean ◽  
Vibrational Anisotropy

Abstract. The formation of high-pressure oxyhydroxide phases spanned by the components AlOOH–FeOOH–MgSiO2(OH)2 in experiments suggests their capability to retain hydrogen in Earth's lower mantle. Understanding the vibrational properties of high-pressure phases provides the basis for assessing their thermal properties, which are required to compute phase diagrams and physical properties. Vibrational properties can be highly anisotropic, in particular for materials with crystal structures of low symmetry that contain directed structural groups or components. We used nuclear resonant inelastic X-ray scattering (NRIXS) to probe lattice vibrations that involve motions of 57Fe atoms in δ-(Al0.87Fe0.13)OOH single crystals. From the recorded single-crystal NRIXS spectra, we calculated projections of the partial phonon density of states along different crystallographic directions. To describe the anisotropy of central vibrational properties, we define and derive tensors for the partial phonon density of states, the Lamb–Mössbauer factor, the mean kinetic energy per vibrational mode, and the mean force constant of 57Fe atoms. We further show how the anisotropy of the Lamb–Mössbauer factor can be translated into anisotropic displacement parameters for 57Fe atoms and relate our findings on vibrational anisotropy to the crystal structure of δ-(Al,Fe)OOH. As a potential application of single-crystal NRIXS at high pressures, we discuss the evaluation of anisotropic thermal stresses in the context of elastic geobarometry for mineral inclusions. Our results on single crystals of δ-(Al,Fe)OOH demonstrate the sensitivity of NRIXS to vibrational anisotropy and provide an in-depth description of the vibrational behavior of Fe3+ cations in a crystal structure that may motivate future applications of NRIXS to study anisotropic vibrational properties of minerals.

scholarly journals Crystal structure refinement of magnesium zinc divanadate, MgZnV2O7, from powder X-ray diffraction data

2021 ◽  
Vol 77 (6) ◽  
pp. 588-591
Author(s):  
Stephanie J. Hong ◽  
Jun Li ◽  
Mas A. Subramanian
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Structure Refinement ◽  
Atomic Ratio ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Trigonal Bipyramidal ◽  
Wyckoff Position ◽  
Distorted Trigonal Bipyramidal

The crystal structure of magnesium zinc divanadate, MgZnV2O7, was determined and refined from laboratory X-ray powder diffraction data. The title compound was synthesized by a solid-state reaction at 1023 K in air. The crystal structure is isotypic with Mn0.6Zn1.4V2O7 (C2/m; Z = 6) and is related to the crystal structure of thortveitite. The asymmetric unit contains two metal sites with statistically distributed magnesium and zinc atoms with the atomic ratio close to 1:1. One (Mg/Zn) metal site (M1) is located on Wyckoff position 8j and the other (M2) on 4h. Three V sites (all on 4i), and eight O (three 8j, four 4i, and one 2b) sites complete the asymmetric unit. The structure is an alternate stacking of V2O7 layers and (Mg/Zn) atom layers along [20\overline{1}]. It is distinct from other related structures in that each V2O7 layer consists of two groups: a V2O7 dimer and a V4O14 tetramer. Mixed-occupied M1 and M2 are coordinated by oxygen atoms in distorted trigonal bipyramidal and octahedral sites, respectively.

The synthesis, molecular and crystal structure of the 1:1 adduct of triphenyltin chloride with 2,3-diphenylthiazolidin-4-one

1995 ◽  
Vol 73 (1) ◽  
pp. 95-99 ◽  
Author(s):  
Frank E. Smith ◽  
Rosemary C. Hynes ◽  
John Tierney ◽  
Ying Z. Zhang ◽  
George Eng
Keyword(s):  
Crystal Structure ◽  
Structural Analysis ◽  
Oxygen Atom ◽  
Dutch Elm Disease ◽  
Monoclinic Space Group ◽  
Monodentate Ligand ◽  
X Ray ◽  
Trigonal Bipyramidal ◽  
Triphenyltin Chloride ◽  
Mössbauer Data

The title compound was synthesized as part of an effort to produce a more effective fungicide to combat Dutch Elm Disease (DED), which is caused by the fungus Ceratocystisulmi. A full X-ray structural analysis of the 1:1 adduct has been carried out and the results are reported along with the Mössbauer data for the compound. The crystals are monoclinic, space group P21/a with a = 19.240(3) Å, b = 9.1463(24) Å, c = 19.3512(24) Å, β = 118.874(8)°, V = 2982.0(10) Å3, z = 4, and Dcalc = 1.427 Mg m−3. The final discrepancy factors are RF = 0.056 and Rw = 0.058 for 1915 significant reflections. The QS and IS values in the Mössbauer spectrum of the complex are 3.08 mm s−1 and 1.28 mm s−1, respectively. The 2,3-diphenylthiazolidin-4-one behaves as a monodentate ligand and coordinates to the tin through the oxygen atom. The complex exhibits a trigonal bipyramidal configuration with the three phenyl groups in equatorial positions and the chloride and ligand oxygen occupying the apical sites. Keywords: triorganotin, fungicide, Dutch Elm Disease, thiazolidin-4-one.

Darstellung und Charakterisierung von Rubidiumhydrogencyanamid/Synthesis and Characterization of Rubidium Hydrogen Cyanamide

1999 ◽  
Vol 54 (11) ◽  
pp. 1375-1378 ◽  
Author(s):  
Michael Becker ◽  
Martin Jansen
Keyword(s):  
Crystal Structure ◽  
Liquid Ammonia ◽  
Synthesis And Characterization ◽  
Hydrogen Cyanamide ◽  
X Ray ◽  
Bond Lengths

The synthesis of RbHCN2 was carried out by reaction of cyanamide with rubidium amide in liquid ammonia. The crystal structure has been determinedo by x-ray powder methods (orthorhombic, P21,21,21, a = 7.299(1), b = 9.435(1), c = 9.420(1) Å; Z = 8). The anion is slightly bent (174°) and exhibits two different bond lengths (C-N: 1.17, HN-C: 1.31 Å).

scholarly journals Über die Reaktion von Wolframhexachlorid mit Se4N2; Kristallstruktur von PPh4[WCl5(NSeCl)] / On the Reaction of Tungsten Hexachloride with Se4N2; Crystal Structure of PPh4[WCl5(NSeCl)]

1991 ◽  
Vol 46 (12) ◽  
pp. 1625-1628 ◽  
Author(s):  
Stefan Vogler ◽  
Werner Massa ◽  
Kurt Dehnicke
Keyword(s):  
Crystal Structure ◽  
Double Bond ◽  
Structure Determination ◽  
Space Group ◽  
X Ray ◽  
Bond Lengths ◽  
Tetraphenylphosphonium Chloride ◽  
Tungsten Hexachloride

The reaction of tungsten hexachloride with Se4N2 leads to [WCl4(NSeCl)]2, which reacts with pyridine to form [WCl4(NSeCl)Py], and with tetraphenylphosphonium chloride to form PPh4[WCl5(NSeCl)], which was characterized by an X-ray structure determination. Space group P21, Z = 2, 1657 observed unique reflections, R = 0.074, wR = 0.061. Lattice dimensions at —80 C: a = 710.7(1), b = 2217.9(4), c = 953.6(2) pm; β = 111.93(3) . The [WCl5(NSeCl)]- ion possesses an almost linear WNSe group with bond lengths WN = 188 pm, corresponding to a double bond, and NSe = 200 pm.

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