The determination of composition and thermal history of plagioclase by the X-ray powder method

1955 ◽  
Vol 30 (229) ◽  
pp. 648-656 ◽  
Author(s):  
J. Goodyear ◽  
W. J. Duffin
Keyword(s):  
Chemical Composition ◽  
Low Temperature ◽  
Similar Composition ◽  
X Ray ◽  
Naturally Occurring ◽  
Cell Dimensions ◽  
History Of ◽  
Unit Cell Dimensions ◽  
Ray Patterns

In a recent paper (hereafter referred to as GD) Goodyear and Dufiln (1954) described X-ray powder data for a number of synthetic and chemically analysed plagioclases of composition An0Abl00-Anl00Ab0. Important aspects of this work were a correlation of the X-ray patterns with chemical composition, and a distinction between the pattern of a naturally occurring material of low-temperature origin and that of a synthetic of similar composition. The investigation showed quite clearly that the unit-cell dimensions of a synthetic plagioelase depend but little on composition from An0Abl00 to An70Ab30, whilst they differ from those of the low-temperature modification greatly for albite, to a lessening degree as the composition approaches An70Ab30, and practically not at all in the range An70Ab30-Anl00Ab0.

An X-ray determinative method for the divalent cation ratio in the triphylite-lithiophilite series

1984 ◽  
Vol 48 (348) ◽  
pp. 373-381 ◽  
Author(s):  
Andrié-Mathieu Fransolet ◽  
Diano Antenucci ◽  
Jean-Marie Speetjens ◽  
Pierre Tarte
Keyword(s):  
Chemical Composition ◽  
Divalent Cation ◽  
Cell Parameter ◽  
X Ray ◽  
Cell Parameters ◽  
Cation Content ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Best Fit

Abstract The powder diffractograms of twenty wet chemically analysed samples in the isomorphous triphylite-lithiophilite series and five synthesized members with Fe/(Fe + Mn) = 1, 0.75, 0.50, 0.25, and 0.0, were recorded. Their unit cell dimensions were accurately refined in order to find a reliable method for semi-quantitative determination of the divalent cation content of these minerals. A multivariate best fit analysis based on Kummell’s procedure shows the marked influence of Fe2+ and Mg2+ on the cell dimensions, as well as that of small amounts of Fe3+ substituting for Mn2+, following LiMn2+ → □ Fe3+. The best representation of the correlation between chemical composition and cell parameters is given by the equations: a = 6.1041 − 0.0245 Fetot − 0.049 Mg2+ b = 10.4511 − Fetot − 0.082 Mg2+ c = 4.7400 − 0.0130(Fe2+ + Mg2+) − 0.025 Fe3+. No evidence of non-linearity has been found for the variation of the three cell dimensions with the chemical composition. Assuming the absence of appreciable amounts of Mg2+, the following set of equations is proposed: Fetot = 41(6.104–a); Fetot = 35(10.451–b); Fetot = 77(4.740–c) in which the c dimension gives a relatively poor estimate. Two sets of determinative graphs were constructed, one based on the cell parameter variation, and the other on the 311, 222, and 142 reflection angular positions, v. the total iron content of these minerals. These two methods, whose reliability is examined, can be used for determination of the divalent cation content, provided the samples contain less than about 0.5 wt.% Na2O, 0.5 wt.% CaO, and 3 wt. % Fe2O3, and are homogeneous.

X-Ray Powder Diffraction (XRPD)

2016 ◽  
pp. 326-341 ◽  
Author(s):  
Robert Heimann
Keyword(s):  
Powder Diffraction ◽  
X Rays ◽  
Powder Diffraction File ◽  
Thin Beam ◽  
Archaeological Ceramics ◽  
X Ray ◽  
Analytical Technique ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

X-ray powder diffraction (XRPD) is an important tool to determine the phase composition of archaeological ceramics. In principle, a thin beam of X-rays incident to a lattice plane of crystalline matter is scattered in specific directions and angles depending on the distances of atoms. This allows determination of characteristic unit cell dimensions and serves to unambiguously identify crystalline phases in the ceramics. In this chapter, generation of X-rays and the theory of diffraction will be briefly discussed as well as equipment, focusing conditions, and sample preparation procedures of common XRPD methods. The X-ray pattern obtained will provide an analytical fingerprint that can be matched against the Powder Diffraction File of the International Centre for Diffraction Data. Examples will be given of application of this analytical technique to archaeological clays and ceramics.

Structure Determination of Al2CuMg Precipitates in Al-Cu-Mg Alloys by Structure Refinement and Quantitative Image Comparison

2000 ◽  
Vol 6 (S2) ◽  
pp. 1030-1031
Author(s):  
R. Kilaas ◽  
V. Radmilovic
Keyword(s):  
Structure Refinement ◽  
Metallic Phase ◽  
S Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Low Weight ◽  
Cell Dimensions ◽  
Quantitative Image ◽  
Unit Cell Dimensions

Al-Cu-Mg based alloys are of significant interest for aerospace and other applications, due to their low weight, mechanical strength and corrosion resistance. Their mechanical properties are based on a dispersion of S-phase precipitates, which have the composition Al2CuMg. The crystal structure of this inter-metallic phase has been studied using different diffraction techniques for more than five decades. While several models have been proposed for the structure of S-phase[l], only one of the previously proposed models were found to give a reasonable fit to our experimental data. This model, shown in Fig. 1 and given by Perlitz and Westgren (PW) [2] based on X-ray diffraction data, is orthorhombic with unit cell dimensions a = 0:4 nm, b = 0.923 nm, and c = 0.714 nm, space group Cmcm, containing 16 atoms in the ratio Al:Cu:Mg = 2:1:1.Several HREM images of S-phase precipitates located near the edge of the foil, Fig. 2, recorded along the [100]s and [010]s directions, were digitized from film and used for analysis.

The Preparation, Spectroscopic Characterization and X-Ray Structure of the Salt [Pt(η1 -C6H9)(Cy2PCH2CH2PCy2)(PPh3)]HCO3·3H2O Containing the Discrete, Uncoordinated, Hydrogen-Bonded Dimeric Bicarbonate Dianion [(HCO3)(H2O)3]22-

1999 ◽  
Vol 52 (10) ◽  
pp. 949 ◽  
Author(s):  
Martin A. Bennett ◽  
Glen B. Robertson ◽  
Pramesh N. Kapoor
Keyword(s):  
Low Temperature ◽  
Spectroscopic Characterization ◽  
Coordination Geometry ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
X Ray ◽  
Cell Dimensions ◽  
R Value ◽  
Unit Cell Dimensions ◽  
Hydrogen Bonded

Reaction of the cyclohexyne–platinum(0) complex [Pt(η2-C6H8)(Cy2PCH2CH2PCy2)]* with water and CO2 in the presence of triphenylphosphine gives the bicarbonate salt of the (η1-cyclohexenyl)platinum(II) cation, [Pt(η1-C6H9)(Cy2PCH2CH2 PCy2)(PPh3)] [HCO3] · 3H2O, which has been characterized by n.m.r. spectroscopy and single-crystal X-ray diffraction at low temperature. Crystals are triclinic, space group P1– with unit cell dimensions a 20.315(2), b 12.782(1), c 10.694(1) Å, α 66.61(1), β 104.73(1), γ 102.11(1)˚, and Z 2. The structure was refined to a final R value of 0.036 with use of 7553 reflections [I > 3σ(I)]. The cation has the expected, somewhat distorted planar coordination geometry; the anion consists of discrete, hydrogen-bonded dimers [(HCO3)(H2O)3]22-.

An X-Ray Structure Determination of the Twinned Crystals of Dinitrato-2,2′-dipyridylsilver(II)

1972 ◽  
Vol 50 (3) ◽  
pp. 315-323 ◽  
Author(s):  
G. W. Bushnell ◽  
M. A. Khan
Keyword(s):  
Silver Atom ◽  
Unit Cell ◽  
Planar Geometry ◽  
X Ray ◽  
Square Planar ◽  
Distorted Octahedral ◽  
Cell Dimensions ◽  
The Mean ◽  
Unit Cell Dimensions

The crystal structure of dinitrato-2,2′-dipyridylsilver(II) has been solved and refined to an R-value of 0.070. Four circle diffractometer measurements were obtained from the twinned triclinic crystals. The unit cell dimensions at 22 °C are: a = 697.5 ± 0.2 pm, b = 999.4 ± 0.2 pm, c = 1032.2 ± 0.2 pm, α = 113.46 ± 0.02°, β = 100.71 ± 0.02°, γ = 95.28 ± 0.02°. The space group is [Formula: see text] (No. 2) with two molecules per unit cell. The density is 2.06 ± 0.04 g cm−3 (measured), 2.02 g cm−3 (calculated). The four shortest bond lengths to silver are: Ag—O(1), 214.8 ± 1.5 pm; Ag—O(4), 213.6 ± 1.5 pm; Ag—N(1), 212.4 ± 1.6 pm; Ag—N(2), 220.7 ± 1.6 pm. These four bonds are distorted from square planar geometry with the silver atom lying 19.90 ± 0.17 pm out of the mean plane of the other four atoms. There are also long bonds to the nitrato groups of neighboring molecules: Ag—O(1′), 275.3 ± 1.3 pm; Ag—O(2″), 276.3 ± 1.6 pm. Inclusion of these bonds gives a distorted octahedral silver coordination. Though predominantly unidentate, there is a slight tendency toward bidentate bonding in both nitrato ligands: Ag—O(2), 305.8 ± 1.4 pm; Ag—O(5), 295.0 ± 1.7 pm. O(2) and O(5) approach the convex side of the distorted square planar coordination. The deviation from planarity of the closely bonded square, and angular distortions in the above mentioned octahedral coordination can be rationalized by considering the silver as eight coordinate. The bonds to silver may be grouped 4:2:2 by length or 4:3:1 by angular disposition.

Reaktion von 1.4-Dienen mit Metallkomplexen, I Darstellung und Röntgenstrukturanalyse eines π-enyl-Komplexes der Zusammensetzung (C8H13PdCl)2/ Reaction of 1,4-Dienes with Metal Complexes, I Synthesis and X-ray Structure Determination of a π-enyl Complex of Composition (C8H18PdCl)2

1976 ◽  
Vol 31 (4) ◽  
pp. 455-462 ◽  
Author(s):  
Peter Feldhaus ◽  
Richard Ratka ◽  
Hermann Schmid ◽  
Manfred L. Ziegler
Keyword(s):  
Metal Complexes ◽  
Structure Determination ◽  
Three Dimensional ◽  
Fourier Methods ◽  
X Ray ◽  
H Nmr ◽  
Nmr Data ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

Reaction of (C6H5CN)2PdCl2 and 1,3-dimethylenecyclohexane led to an exocyclic π-enyl complex of formula (C8H13PdCl)2-bis(η3-2-methylene-6-methylcyclohexyl)(di-µ-chloro)-dipalladium. IR and 1H NMR data are in agreement with this formulation.The compound is monoclinic, with unit cell dimensions α = 499.97 ± 0.08, b =1342.26 ± 0.19, c =1379.60 ± 0.20 pm, β = 99.43 ± 0.02°, space group C5h2-P21/C, Ζ = 2, dX-ray = 1.83 g/cm3.The structure was determined from three-dimensional X-ray data by Patterson and Fourier methods. Least squares refinement by use of 1045 independent reflections has reached R1 = 5.6%.

Powder diffraction data and Rietveld refinement of metastable t-ZrO2 at low temperature

1997 ◽  
Vol 12 (2) ◽  
pp. 96-98 ◽  
Author(s):  
J. Málek ◽  
L. Beneš ◽  
T. Mitsuhashi
Keyword(s):  
Low Temperature ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Space Group ◽  
X Ray ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

Indexed X-ray powder diffraction data are reported for the low temperature tetragonal ZrO2 obtained by crystallization of zirconia gel. The structure was refined by the Rietveld technique on the basis of space group P42/nmc. Refined unit cell dimensions are a = 3.5984(5) Å, c = 5.152(1) Å, V = 66.71 Å3, Dx=6.135 g/cm3, F18=62 (0.012, 24), RP=8.99, Rwp=11.48, RB=3.13.

Direct phase determination in electron crystallography: Linear polymers

1992 ◽  
Vol 50 (2) ◽  
pp. 1442-1443
Author(s):  
Douglas L. Dorset
Keyword(s):  
Chain Structure ◽  
Crystal Structure Analysis ◽  
Crystallographic Structure ◽  
Linear Polymers ◽  
X Ray ◽  
Cell Dimensions ◽  
Diffraction Patterns ◽  
Crystal Electron ◽  
Unit Cell Dimensions

Perhaps no other class of organic molecule has been the subject of quantitative electron crystallographic structure analyses than the linear polymers. Given the real restrictions to crystallization of these materials, the reason for this is very clear, since one can at least obtain single crystal electron diffraction patterns from the chain-folded lamellae for determination of unit cell dimensions and symmetry and for measurement of diffracted intensities. The usual methodology for crystal structure analysis with the observed intensity data is based on the procedure used in fiber X-ray analyses. That is, one determines the X-ray crystal structures of representative monomer and/or oligomer segments of the polymer chain to see what part of the repeat can be held conformationally rigid. These rigid units are concatenated through “linkage bonds”, around which conformational twists are allowed and the search for the stable chain structure is based on the simultaneous minimization of the crystallographic R-factor and an internal energy calculated from nonbonded atomatom potential functions.

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