Al analogue of chayesite from a lamproite of Cancarix, SE Spain, and its crystal structure

2020 ◽  
Vol 196 (3) ◽  
pp. 193-198
Author(s):  
Natalia V. Zubkova ◽  
Nikita V. Chukanov ◽  
Christof Schäfer ◽  
Konstantin V. Van ◽  
Igor V. Pekov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Empirical Formula ◽  
Structure Refinement ◽  
Crystal Chemical ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
X Ray Diffraction ◽  
Se Spain ◽  
X Ray

Al analogue of chayesite (with Al > Fe3+) was found in a lamproite from Cancarix, SE Spain. The mineral forms green thick-tabular crystals up to 0.4 mm across in cavities. The empirical formula derived from EMP measurements and calculated on the basis of 17 Mg + Fe + Al + Si apfu is (K0.75 Na0.20 Ca0.11)Mg3.04 Fe0.99 Al1.18 Si11.80 O30. The crystal structure was determined from single crystal X-ray diffraction data ( R = 2.38%). The mineral is hexagonal, space group P 6/ mcc, a = 10.09199(12), c = 14.35079(19) Å, V = 1265.78(3) Å3, Z = 2. Fe is predominantly divalent. Al is mainly distributed between the octahedral A site and the tetrahedral T 2 site. The crystal chemical formula derived from the structure refinement is C (K0.73 Na0.16 Ca0.11)B (Na0.02)4 A(Mg0.42 Al0.29 Fe0.29)2 T 2(Mg0.71 Fe0.16 Al0.13)3 T 1(Si0.985 Al0.015)12 O30.

scholarly journals Redetermination of Sr2PdO3 from single-crystal X-ray data

2019 ◽  
Vol 75 (1) ◽  
pp. 30-32
Author(s):  
Gohil S. Thakur ◽  
Hans Reuter ◽  
Claudia Felser ◽  
Martin Jansen
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Diffraction Data ◽  
Structure Refinement ◽  
Structure Type ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Cell Parameters ◽  
Anisotropic Displacement Parameters

The crystal structure redetermination of Sr2PdO3 (distrontium palladium trioxide) was carried out using high-quality single-crystal X-ray data. The Sr2PdO3 structure has been described previously in at least three reports [Wasel-Nielen & Hoppe (1970). Z. Anorg. Allg. Chem. 375, 209–213; Muller & Roy (1971). Adv. Chem. Ser. 98, 28–38; Nagata et al. (2002). J. Alloys Compd. 346, 50–56], all based on powder X-ray diffraction data. The current structure refinement of Sr2PdO3, as compared to previous powder data refinements, leads to more precise cell parameters and fractional coordinates, together with anisotropic displacement parameters for all sites. The compound is confirmed to have the orthorhombic Sr2CuO3 structure type (space group Immm) as reported previously. The structure consists of infinite chains of corner-sharing PdO4 plaquettes interspersed by SrII atoms. A brief comparison of Sr2PdO3 with the related K2NiF4 structure type is given.

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 crystal structure of schairerite and its relationship to sulphohalite

1975 ◽  
Vol 40 (310) ◽  
pp. 131-139 ◽  
Author(s):  
L. Fanfani ◽  
A. Nunzi ◽  
P. F. Zanazzi ◽  
A. R. Zanzari ◽  
C. Sabelli
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Hexagonal Lattice ◽  
Three Dimensional ◽  
Chemical Formula ◽  
X Ray Diffraction ◽  
Cell Content ◽  
X Ray ◽  
Structural Framework ◽  
Unequal Number

SummaryThe crystal structure of schairerite from Searles Lake, California, has been determined employing X-ray diffraction data collected on a single-crystal diffractometer. The crystal structure was refined by least-squares methods employing isotropic thermal parameters to a final R index of 0·07 for 2536 independent observed reflections. The cell content is 3[Na21(SO4)7F6Cl]. The space group is P31m with a 12·197 A and c 19·259 Å. Schairerite exhibits a marked sub-cell (a 7·042 Å, the same c axis and P3m1 symmetry), which may be related to the unit cell of sulphohalite when described in a hexagonal lattice.The crystal structure of schairerite may be considered as consisting of seven sheets of Na+ ions perpendicular to the c axis. These sheets are connected to each other .building up a three-dimensional framework. The Na+ ions in these sheets are arranged in an array built up of hexagons and triangles. Sulphur atoms lie in the sheets at the centres of each hexagon, the halogen atoms lying between the sheets midway between the centres of two triangles. A comparison with sulphohalite shows that the close lattice analogies may be related to a similar atomic arrangement. Apart from the differences in chemical formula (F:C1 ratio 1:1 in sulphohalite), the main difference in the structural framework consists of the unequal number of Na+ sheets (six in sulphohalite) and in the SO42− tetrahedra orientation.

scholarly journals Crystal structure and revision of the chemical formula of georgiadesite, Pb4(AsO3)Cl4(OH)

2000 ◽  
Vol 64 (5) ◽  
pp. 879-884 ◽  
Author(s):  
M. Pasero ◽  
D. Vacchiano
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Structural Study ◽  
Diffraction Data ◽  
Chemical Formula ◽  
X Ray Diffraction ◽  
X Ray ◽  
Trigonal Prisms

AbstractThe crystal structure of the rare secondary lead mineral georgiadesite has been solved from single-crystal X-ray diffraction data (R = 0.071). The structure can be visualized in terms of alternating puckered (100) layers of [Pbϕ6] octahedra and [Pbϕ8] bicapped trigonal prisms (ϕ = generic anion). Lead also occurs in irregular, lopsided polyhedra. This structural study shows unambiguously that arsenic occurs as As3+ and not as As5+. The chemical formula of georgiadesite has therefore been revised, on structural grounds, to Pb4(AsO3)Cl4(OH).

The crystal structure of nonmetamict Nb-rich zirconolite-3T from the Eifel paleovolcanic region, Germany

2018 ◽  
Vol 233 (7) ◽  
pp. 463-468 ◽  
Author(s):  
Natalia V. Zubkova ◽  
Nikita V. Chukanov ◽  
Igor V. Pekov ◽  
Bernd Ternes ◽  
Willi Schüller ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Empirical Formula ◽  
Structural Model ◽  
Crystal Chemical ◽  
Single Crystal Xrd ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

Abstract The crystal structure of a Nb-rich zirconolite-3T from the Laach Lake volcano, Eifel, Germany, was studied by single-crystal XRD (R=0.0295). The mineral is trigonal, P3121; unit-cell dimensions are: a=7.3095(2), c=16.9604(5) Å, V=784.78(4) Å3. The empirical formula based on 14 O atoms (Z=3) is Ca1.28Ce0.31La0.14Nd0.12Pr0.06Th0.16 Zr1.94Hf0.04Ti1.74Nb1.22Fe0.72Mn0.28O14. The crystal-chemical formula based upon the structural model is: VIII(Ca0.70 Ce0.30)VIII(Ca0.58Ce0.32Th0.10)VII(Zr0.88Th0.04Hf0.02□0.06)2VII(□0.94 Zr0.06)2VI(Ti0.72Nb0.26Zr0.02)VI(Ti0.50Nb0.47Zr0.03)2IV(Fe0.355 Mn0.145)2O14 (Z=3).

scholarly journals Synthesis and Rietveld crystal structure refinement of mackinawite, tetragonal FeS

1995 ◽  
Vol 59 (397) ◽  
pp. 677-683 ◽  
Author(s):  
A. R. Lennie ◽  
S. A. T. Redfern ◽  
P. F. Schofield ◽  
D. J. Vaughan
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Structure Refinement ◽  
X Rays ◽  
Crystal Structure Refinement ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Data Set ◽  
X Ray ◽  
Cell Parameters

AbstractMackinawite, tetragonal FeS, has been synthesised by reacting iron with Na2S solutions. A Rietveld structure refinement of X-ray powder diffraction data, recorded using X-rays monochromated from synchrotron radiation with a wavelength of 0.6023 Å, has been performed. The structure has been refined in the tetragonal space group, P4/nmm, and has the following cell parameters: a = 3.6735(4), c = 5.0328(7) Å, V = 67.914(24) Å3. Our refinement shows that the FeS4 tetrahedron in mackinawite is almost perfectly regular, with a much smaller distortion than has been previously reported. An improved X-ray diffraction data set is provided.

Metavivianite, Fe2+Fe3+2(PO4)2(OH)2·6H2O: new data and formula revision

2012 ◽  
Vol 76 (3) ◽  
pp. 725-741 ◽  
Author(s):  
N. V. Chukanov ◽  
R. Scholz ◽  
S. M. Aksenov ◽  
R. K. Rastsvetaeva ◽  
I. V. Pekov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Gas Chromatography ◽  
Optical Properties ◽  
Crystal Chemical ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
Homogeneous Sample ◽  
X Ray ◽  
Composition Structure ◽  
First Time

AbstractThe composition, structure, X-ray powder diffraction pattern, optical properties, density, infrared, Raman and Mössbauer spectra, and thermal properties of a homogeneous sample of metavivianite from the Boa Vista pegmatite, near Galiléia, Minas Gerais, Brazil are reported for the first time. Metavivianite is biaxial (+) with α = 1.600(3), β = 1.640(3), γ = 1.685(3) and 2Vmeas= 85(5)°. The measured and calculated densities are Dmeas= 2.56(2) and Dcalc= 2.579 g cm–3. The chemical composition, based on electronmicroprobe analyses, Mössbauer spectroscopy (to determine the Fe2+:Fe3+ratio) and gas chromatography (to determine H2O) is MgO 0.70, MnO 0.92, FeO 17.98, Fe2O326.60, P2O528.62, H2O 26.5; total 101.32 wt.%. The empirical formula is (Fe3+1.64Fe2+1.23Mg0.085Mn0.06)Σ3.015(PO4)1.98(OH)1.72·6.36H2O. Metavivianite is triclinic, P1̄, a = 7.989(1), b = 9.321(2), c = 4.629(1) Å, α = 97.34(1), β = 95.96(1), γ = 108.59(2)°, V = 320.18(11) Å3and Z = 1. The crystal structure was solved using a single-crystal techniques to an agreement index R = 6.0%. The dominant cations in the independent sites are Fe2+and Fe3+, with multiplicities of 1 and 2, respectively. The simplified crystal-chemical formula for metavivianite is Fe2+(Fe3+, Fe2+)2(PO4)2(OH,H2O)2·6H2O; the endmember formula is Fe2+Fe3+2(PO4)2(OH)2·6H2O, which is dimorphous with ferrostrunzite.

Crystal Structure Refinement of M(NCNH)2 (M = Fe, Co) Based on Combined Neutron and X-ray Diffraction Data

2011 ◽  
Vol 637 (9) ◽  
pp. 1089-1091 ◽  
Author(s):  
Xiaojuan Tang ◽  
Andreas Houben ◽  
Xiaohui Liu ◽  
Ludwig Stork ◽  
Richard Dronskowski
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Structure Refinement ◽  
Crystal Structure Refinement ◽  
X Ray Diffraction ◽  
X Ray

The effects of composition upon the high-pressure behaviour of amphiboles: compression of gedrite to 7 GPa and a comparison with anthophyllite and proto-amphibole

2012 ◽  
Vol 76 (4) ◽  
pp. 987-995 ◽  
Author(s):  
F. Nestola ◽  
D. Pasqual ◽  
M. D. Welch ◽  
R. Oberti
Keyword(s):  
North Carolina ◽  
High Pressure ◽  
Maximum Pressure ◽  
Published Data ◽  
Crystal Chemical ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
X Ray Diffraction ◽  
X Ray ◽  
Al Content

AbstractA single-crystal X-ray diffraction study of a sample of natural gedrite from North Carolina, USA, with the crystal-chemical formula ANa0.47B(Na0.03Mg0.97Fe0.942+Mn0.02Ca0.04)C(Mg3.52Fe0.282+Al1.15Ti0.054+)T(Si6.31Al1.69)O22W(OH)2, up to a maximum pressure of 7 GPa, revealed the following bulk and axial moduli and their pressure derivatives: K0T = 91.2(6) GPa [K0T' = 6.3(2)]; K0T(a) = 60.5(6) GPa [K0T(a)' = 6.1(2)]; K0T(b) = 122.8(2.6) GPa [K0T(b)' = 5.7(8)]; K0T (c) = 119.7(1.5) GPa [K0T(c)' = 5.1(5)]. Gedrite has a much higher bulk modulus than anthophyllite (66 GPa) and proto-amphibole (64 GPa). All of the three axial moduli of gedrite are higher than those of these two other orthoamphiboles. The greater stiffness of gedrite along [100] is due to its high ANa content, which is almost zero in anthophyllite and proto-amphibole. The much greater stiffness parallel to the (100) plane of gedrite compared with the two other amphiboles is probably due to its high CAl content. A comparison is made with published data available for orthorhombic B(Mg, Mn, Fe) and monoclinic BCa amphiboles to identify correlations between crystal-chemistry and compressibility in amphiboles.

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