Tungusite: new data, relationship with gyrolite and structural model

1995 ◽  
Vol 59 (396) ◽  
pp. 535-543 ◽  
Author(s):  
Giovanni Ferraris ◽  
Alessandro Pavese ◽  
Svetlana V. Soboleva
Keyword(s):  
Solid Solution ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structural Model ◽  
Substitutional Solid Solution ◽  
Chemical Analyses ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Tetrahedral Layer ◽  
The Ideal

AbstractNew chemical analyses, electron and X-ray powder diffraction data, and comparison with gyrolite and reyerite show that tungusite has the ideal formula , symmetry P and a = 9.714(9), b = 9.721(9), c = 22.09(3), α = 90.13(1)°, β = 98.3(2)°, γ = 120.0(1)°, Z = 1. A structural model for tungusite is derived by splitting the double tetrahedral layer of reyerite and inserting a trioctahedral X sheet which is ideally occupied by Fe2+. Polytypism phenomena due to different relative positions between tetrahedral and X sheets are discussed. A substitutional solid solution represented by the formula [Ca14(OH)8]Si24−yAlyO60[NaxM9−(x+z)□z(OH)14−(x+y+2z)·(x+y+2z)H2O] includes tungusite (x = y = z = 0, M = Fe2+ and gyrolite (x = 1, y = 1, z = 6, M = Ca).

Crystallographic study of ternary ordered skutterudite IrGe1.5Se1.5

2010 ◽  
Vol 25 (3) ◽  
pp. 247-252 ◽  
Author(s):  
F. Laufek ◽  
J. Návrátil
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Crystallographic Data ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Crystallographic Study ◽  
Related Phase ◽  
The Ideal

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.

Cristobalite-Related Phases in the NaAlO2–NaAlSiO4 System. I. Two Tetragonal and Two Orthorhombic Structures

1998 ◽  
Vol 54 (5) ◽  
pp. 531-546 ◽  
Author(s):  
J. G. Thompson ◽  
R. L. Withers ◽  
A. Melnitchenko ◽  
S. R. Palethorpe
Keyword(s):  
Crystal Structures ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Structure Type ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Modulation Wave ◽  
Wave Approach ◽  
The Ideal

The crystal structures of five new cristobalite-related sodium aluminosilicates with four different structure types from the system Na2−x Al2−x Si x O4, 0 ≤ x ≤ 1 [Na1.95Al1.95Si0.05O4, P41212, a = 5.2997 (6), c = 7.0758 (9) Å; Na1.75Al1.75Si0.25O4, Pbca, a = 10.4221 (11), b = 14.264 (3), c = 5.2110 (5) Å; Na1.65Al1.65Si0.35O4, P41212, a = 10.3872 (7), c = 7.1589 (8) Å; Na1.55Al1.55Si0.45O4, Pbca, a = 10.385 (1), b = 14.198 (3), c = 5.1925 (6) Å; Na1.15Al1.15Si0.85O4, Pb21 a, a = 10.214 (2), b = 14.226 (7), c = 10.308 (1) Å], have been refined by the Rietveld method from X-ray powder diffraction data. Plausible starting models were derived for the x = 0.05, 0.25 and 0.45 structures by analogy. Starting models for the x = 0.35 and 0.85 structures, with previously unreported structure types, were derived from a modulation wave approach based on distortion of the ideal C9 structure type and assuming regular SiO4 and AlO4 tetrahedra.

On the new mineral theophrastite, a nickel hydroxide, from Unst, Shetland, Scotland

1982 ◽  
Vol 46 (338) ◽  
pp. 1-5 ◽  
Author(s):  
A. Livingstone ◽  
D. L. Bish
Keyword(s):  
Solid Solution ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Nickel Hydroxide ◽  
New Mineral ◽  
Solid Solution Series ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Solution Series ◽  
Physical Data

AbstractThe new mineral theophrastite, Ni(OH)2, from Unst, is Mg-bearing and occurs associated with a very poorly crystalline Ni-containing mixed hydroxide of the pyroaurite type and/or zaratite on chromitite. X-ray powder diffraction data show a shift in d spacing toward brucite compared with pure Ni(OH)2. Infrared, thermal, chemical, optical, and physical data are presented together with indexed powder data for fifteen lines ranging from d 4.66Å to 0.90Å. The solid-solution series brucite-theophrastite is briefly discussed.

A Modulation Wave Approach to the Structural Characterization of Three New Cristobalite-Related Sodium Magnesiosilicates

1997 ◽  
Vol 53 (2) ◽  
pp. 203-220 ◽  
Author(s):  
R. L. Withers ◽  
C. Lobo ◽  
J. G. Thompson ◽  
S. Schmid ◽  
R. Stranger
Keyword(s):  
Powder Diffraction ◽  
Structural Characterization ◽  
Diffraction Data ◽  
Structure Type ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Modulation Wave ◽  
Wave Approach ◽  
The Ideal

The crystal structures of three new cristobalite-related sodium magnesiosilicates [Na2MgSiO4, M r = 162.37, orthorhombic, Pna21, a = 10.835 (5), b = 5.279 (12), c = 7.067 (8) Å, D x = 2.668 g cm−3, Z = 4, Cu Kα, λ = 1.5418 Å, μ = 75.96 cm−l, F(000) = 319.87; Na1.74Mg0.79Al0.15Si1.06O4, M r = 157.02, orthorhombic, Pbca, a = 10.487 (7), b = 14.351 (4), c = 5.243 (6) Å, D x = 2.643 g cm−3, Z = 8, Cu Kα, λ = 1.5418 Å, μ = 76.70 cm−l, F(000) = 619.04; Na1.8Mg0.9Si1.1O4, M r = 158.15, tetragonal, P41212, a = 5.330 (6), c = 7.086 (5) Å, D x = 2.609 g cm−3, Z = 2, Cu Kα, λ= 1.5418 Å, μ = 75.44 cm−l, F(000) = 155.94] are determined by Rietveld refinement from X-ray powder diffraction data. Plausible starting models were derived from a modulation wave approach based on the ideal C9 structure type and assuming regular SiO4 and MgO4 tetrahedra.

X-RAY DIFFRACTION STUDY ON THE CRYSTAL STRUCTURE OF Sm1+xBa2−xCu3O7−y

1988 ◽  
Vol 02 (02) ◽  
pp. 583-588 ◽  
Author(s):  
H. ASANO ◽  
Y. YOKOYAMA ◽  
M. NISHINO ◽  
H. KATOH ◽  
H. AKINAGA ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Diffraction Study ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Analysis ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Changes

Crystal structures in solid solution of Sm 1+x Ba 2−x Cu 3 O 7−y (X = 0 - 0.4) have been investigated by Rietveld analysis of X-ray powder diffraction data. The structure changes from orthorhombic to tetragonal at x=0.2. With the increase of x, Tc decreases monotonically from 90 K and the compound becomes semiconducting at x=0.4.

Arsenáty mědi z dobývky na žíle Geschieber - sever (patro Daniel), Svornost, jáchymovský rudní revír (Česká republika)

2020 ◽  
Vol 28 (2) ◽  
pp. 454-465
Author(s):  
Jiří Sejkora ◽  
Bohuslav Bureš
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Empirical Formula ◽  
Unit Cell ◽  
Chemical Analyses ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters

An interesting mineral association of Cu arsenates was found at abandoned ore stope at the Geschieber vein - north at the Daniel level of the Svornost mine, the Jáchymov ore district, Krušné hory, Czech Republic. Tangdanite forms thin tabular crystals up to 3 mm in size and coatings and fine crystalline aggregates on the area up to some cm2. It has light green, bluish-green to emerald green color and perfect cleavage. It is monoclinic, space group C2/c, the unit-cell parameters refined from X-ray powder diffraction data are: a 54.335(12), b 5.579(2), c 10.459(2) Å, β 95.42(3)° and V 3156(2) Å3; its chemical analyses correspond to the empirical formula Ca1.99(Cu8.72Zn0.09Ni0.04Al0.04)Σ8.89[(AsO4)3.83 (PO4)0.14(SiO4)0.03]Σ4.00(SO4)0.41(OH)8.97·9H2O on the basis As+P+Si+V = 4 apfu. The results of Raman and infrared spectroscopy confirmed an absence of carbonate group in studied tangdanite. K-rich lavendulan was found as a relatively abundant sky blue crusts and coatings on the area up to some cm2 and hemispherical aggregates with a radial structure or rarely as a group of thin tabular crystals up to 0.2 mm in size. It is monoclinic, space group P21/n, the unit-cell parameters refined from X-ray powder diffraction data are: a 10.081(12), b 19.469(12), c 10.033(9) Å, β 90.32° and V 1969(2) Å3; its chemical analyses correspond to the empirical formula (Na0.63K0.16)Σ0.79Ca1.12(Cu4.82Al0.01)Σ4.83[(AsO4)3.86(PO4)0.07 (SO4)0.06(SiO4)0.01]Σ4.00Cl0.96·5H2O on the basis As+P+V+Si+S = 4 apfu. Olivenite occurs as olive green spherical aggregates with radial structure up to 8 mm in size and rarely as groups of acicular crystals in association with strashimirite and köttigite. It is orthorhombic, space group Pnnm, the unit-cell parameters refined from X-ray powder diffraction data are: a 8.6204(10), b 8.2332(9), c 5.9337(11) Å and V 421.13(7) Å3; its chemical analyses correspond to the empirical formula (Cu1.94Ni0.01Al0.01)Σ1.96[(AsO4)0.97(VO4)0.02(PO4)0.01]Σ1.00(OH)0.93 on the basis As+V+P = 1 apfu. Strashimirite forms there light green crystalline coatings on the area up to several cm2 and spherical aggregates with a radial structure in association with olivenite and lavendulan. Strashimirite is probably monoclinic, space group P2, the unit-cell parameters refined from X-ray powder diffraction data are: a 9.991(9), b 18.466(9), c 8.986(8) Å, β 96.5(2)° and V 1574(3) Å3; its chemical analyses correspond to the empirical formula (Cu7.83Ni0.18Ca0.09Zn0.06Co0.02Al0.02)Σ8.20 [(AsO4)3.81(PO4)0.07 (SO4)0.07(VO4)0.03(SiO4)0.02]Σ4.00 (OH)4.45·5H2O on the basis As+P+Si+V+S = 4 apfu. Chalcophyllite was found as rare emerald green thin tabular crystals up to 0.5 mm in size and crystalline aggregates. Its chemical composition is possible to express on the basis As+S+P+Si = 7 apfu by the empirical formula Cu17.83Al1.97[(AsO4)4.00(PO4)0.09]Σ4.09[(SO4)2.80(SiO4)0.11]Σ2.91 (OH)23.27·36H2O. Brochantite, devilline, köttigite, erythrite and gypsum were also found in the association with Cu arsenates. The origin of the described mineral association is connected with (sub)recent weathering of primary ore minerals (tennantite, sphalerite, nickelskutterudite) in relatively dry conditions of abandoned mine adits.

The structure of two manganese hexacyanometallates(II): Mn2[Fe(CN)6].8H2O and Mn2[Os(CN)6].8H2O

2002 ◽  
Vol 17 (2) ◽  
pp. 144-148 ◽  
Author(s):  
A. Gómez ◽  
V. H. Lara ◽  
P. Bosch ◽  
E. Reguera
Keyword(s):  
Crystal Structures ◽  
Coordination Sphere ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structural Model ◽  
Rietveld Method ◽  
Monoclinic Space Group ◽  
Powder Diffraction Data ◽  
Crystallization Water ◽  
X Ray

The crystal structures of two manganese hexacyanometallates(II), Mn2[Fe(CN)6].8H2O and Mn2[Os(CN)6].8H2O, were refined from X-ray powder diffraction data using the Rietveld method, with the reported structure for Mn2[Ru(CN)6].8H2O used as a structural model. These compounds are isomorphous and crystallize in the monoclinic space group P21/n. Their crystallization water is not firmly bound and can be removed without disrupting the M–C≡N–Mn network. In the dehydrated complexes, the outer cation (Mn) remains linked to only three N atoms from CN ligands while the inner cation (Fe,Os) preserves its coordination sphere. The IR, Raman, and Mössbauer spectra for the hydrated and anhydrous forms are explained based on the refined structures.

Powder X-ray data for the solid solution [(NH4)3Al1−xFex/2Crx/2(C2O4)3] ·3H2O; 0.10≤x≤0.80

1996 ◽  
Vol 11 (1) ◽  
pp. 2-4
Author(s):  
Mohamed Ezahri ◽  
Georges Coffy ◽  
Bernard F. Mentzen
Keyword(s):  
Solid Solution ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Crystal System

X-ray powder diffraction data are reported for the [(NH4)3Al1−xFex/2Crx/2(C2O4)3]·3H2O solid solution. The crystal system is triclinic with space group P1. Refined unit-cell parameters are given for the compositions x=0.10, 0.50 and 0.80.

Use of TALP with laboratory powder diffraction data from 2D detectors

2013 ◽  
Vol 28 (S2) ◽  
pp. S481-S490
Author(s):  
Oriol Vallcorba ◽  
Anna Crespi ◽  
Jordi Rius ◽  
Carles Miravitlles
Keyword(s):  
Organic Compounds ◽  
Structural Study ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Powder Pattern ◽  
Experimental Setup ◽  
Intensity Data ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Molecular Compounds

The viability of the direct-space strategy TALP (Vallcorba et al., 2012b) to solve crystal structures of molecular compounds from laboratory powder diffraction data is shown. The procedure exploits the accurate metric refined from a ‘Bragg-Brentano’ powder pattern to extract later the intensity data from a second ‘texture-free’ powder pattern with the DAJUST software (Vallcorba et al., 2012a). The experimental setup for collecting this second pattern consists of a circularly collimated X-ray beam and a 2D detector. The sample is placed between two thin Mylar® foils, which reduces or even eliminates preferred orientation. With the combination of the DAJUST and TALP software a preliminary but rigorous structural study of organic compounds can be carried out at the laboratory level. In addition, the time-consuming filling of capillaries with diameters thinner than 0.3mm is avoided.

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