Ba-, Si- and vacancy-rich phlogopites from the talc-bearing sulfide ore deposit of La Creuse, Beaujolais, France

2018 ◽  
Vol 82 (5) ◽  
pp. 1187-1210
Author(s):  
Marie-Lola Pascal ◽  
Michel Fonteilles ◽  
Véronique Tournis ◽  
Benoît Baptiste ◽  
Jean-Louis Robert ◽  
...  
Keyword(s):  
Goodness Of Fit ◽  
Monoclinic Space Group ◽  
Excess Charge ◽  
Formula Unit ◽  
X Ray Diffraction ◽  
Ore Deposit ◽  
Sulfide Ore ◽  
The Common ◽  
The Stability ◽  
High Level

ABSTRACTBa-rich and Si-rich phlogopites occur in the talc-bearing rocks of the La Creuse sulfide ore deposit in Beaujolais, France. They form a group of compositions completely separated from the common Al-rich phlogopites that occur in the surrounding talc-free metasiltites and metarhyolites, with higher Ba and Mg and lower Al contents. The Ba-rich phlogopites have a relatively narrow compositional range (0.24 to 0.80 Ba per formula unit, for 44 valencies) with high and constant Si (5.8 atoms per formula unit, apfu) and Mg + Fe (5.6 apfu), probably buffered by the presence of talc. Compared to low-Al phlogopites from talc-free rocks, the excess charge introduced by the BaK–1 substitution is compensated by interlayer vacancies. Such a high level of interlayer vacancy (0.56 pfu), related to the talc-producing metasomatic conditions, is essential for the stability of this special group of Ba-rich and Si-rich phlogopites.Single crystal X-ray diffraction analyses were performed. Ba-rich and Si-rich phlogopite is monoclinic, space group C2/m, (R = 5.31%) with a = 5.3185(5), b = 9.2136(9), c = 10.1349(11) Å and β = 100.131(11)°. The occupancies of Mg/Fe and K/Ba were refined exploring different vacancies. The solutions giving the best R factor (4.77%) and goodness-of-fit (1.06) are obtained with 15% < vacancy < 40% at the interlayer site.

scholarly journals Prix du pétrole et degré de stabilité de l’OPEP

2009 ◽  
Vol 52 (3) ◽  
pp. 311-323 ◽  
Author(s):  
Antoine Ayoub
Keyword(s):  
Renewable Resource ◽  
Production Plan ◽  
Long Run ◽  
Common Strategy ◽  
The Common ◽  
Petroleum Sector ◽  
The Stability ◽  
The One ◽  
High Level

Abstract The stability of OPEC may be defined as the upholding of a high level of cohesion between the members of this organisation, in order to secure for the whole a certain level of bargaining power that everyone would think to be acceptable at a given time and in a given context. This level of cohesion is mainly estimated by the common will of members to apply rigorously a common strategy regarding the price-quantity of crude petroleum. In the long run, such a strategy would call for a common production plan in order to determine not only the total level of annual production, but also the quotas of each country, the price level and the rate of development of the capacity of production. The aim of this paper is to contribute to the bringing out of a problematic regarding such a production plan as a whole. The main topics are: (1) the necessity of OPEC, (2) the price determination of petroleum, (3) the question of the instability of a coalition. The analysis accounts for the fact that the petroleum sector produces a non-renewable resource, on the one hand, and for the environment and international constraints that the member countries of OPEC have to face in their development process, on the other hand.

Synthesis and Crystal Structure of (1E,2E)-1,2-Di (-3-Nitrobenzylidene) Hydrazine under Micromave Irradiation

2013 ◽  
Vol 787 ◽  
pp. 205-207
Author(s):  
Hong Yan Zhou
Keyword(s):  
Crystal Structure ◽  
Microwave Irradiation ◽  
Monoclinic Space Group ◽  
Stacking Interactions ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
H Nmr ◽  
The Stability ◽  
High Yields

A compound of (1E,2E)-1,2-di (-3-nitrobenzylidene) hydrazine was synthesized under microwave irradiation (500 w), giving high yields of products (93%). Its structure was determined IR, 1H NMR, MS, elemental analysis and X-ray diffraction. The crystal of the compound is Monoclinic, space group P2(1)/n with a = 6.9611(18), b = 7.823(2), c = 12.999(3) Å, α = 90, β = 105.215(4), γ = 90o, V= 683.1(3) Å3, Z=4, Dc=1.450g/cm3,μ=0.110 mm-1, F(000)=308, R=0.0401 and wR = 0.1131 for 1273 observed reflection with I>2σ (I). π-π stacking interactions contribute to the stability of the structure.

Magnesio-ferri-fluoro-hornblende from Portoscuso, Sardinia, Italy: description of a newly approved member of the amphibole supergroup

2016 ◽  
Vol 80 (2) ◽  
pp. 269-275 ◽  
Author(s):  
Roberta Oberti ◽  
Massimo Boiocchi ◽  
Frank C. Hawthorne ◽  
Neil A. Ball ◽  
Luigi Chiappino
Keyword(s):  
Empirical Formula ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Volcanic Rocks ◽  
Polarized Light ◽  
Monoclinic Space Group ◽  
Formula Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Ideal

AbstractMagnesio-ferri-fluoro-hornblende has the ideal formula A□B Ca2C(Mg4Fe3+)T(Si7Al)O22WF2(Hawthorne et al., 2012). The holotype sample described in this work occurs as prismatic crystals in vugs of volcanic rocks (Seruci ignimbrites), found along the coast road ∼5.5 km northeast of Portoscuso, Cagliari, Sardinia; associated minerals are tridymite, todorokite, magnetite, and hematite. The name and the mineral were approved by the IMA CNMNC (2014-091). Holotype magnesio-ferri-fluoro-hornblende is monoclinic, space group C2/m, a = 9.839(5), b = 18.078(9), c = 5.319(3) Å, β = 104.99(3)°, V = 913.9(9) Å3, Z = 2. The density calculated from the empirical formula is 3.315 g cm–3. In plane-polarized light, magnesio-ferri-fluoro-hornblende is pleochroic, X = pale grey (least), Y = dark grey (most), Z = pale brownish grey (intermediate); X^a= 47.6° (β obtuse), Y // b, Z^c= 33.4° (β acute). It is biaxial negative, α = 1.669, β = 1.676, γ = 1.678, all ±0.002; 2Vobs= 74(1)°, 2Vcalc= 56°. The strongest eight lines in the powder X-ray diffraction pattern are [d in Å (I)(hkl)]: 2.711 (100)(151), 8.412 (89)(110), 3.121 (64)(310), 2.553 (61)(2̄02), 3.389 (55)(131), 2.599 (45)(061), 2.164 (36)(261), and 2.738 (34)(3̄31). Electron-microprobe analysis of the refined crystal gave SiO245.34, Al2O36.18, TiO21.22, FeO 15.24, Fe2O36.27, MgO 9.71, MnO 0.78, ZnO 0.06, CaO 10.18, Na2O 1.35, K2O 1.15, F 3.22, Cl 0.30, H2Ocalc 0.37, sum 99.95 wt.%. The empirical formula unit, calculated on the basis of 24 (O, OH, F, Cl) apfu with (OH + F + Cl) = 2 apfu is: (Na0.15K0.22)∑0.37(Na0.25Ca1.66Mn0.09)∑2.00(Mg2.20Fe2+1.94Mn0.01Zn0.01Fe3+0.72Ti0.13)∑5.01(Al1.11Si6.89)∑8.00O22[F1.55(OH)0.37Cl0.08)∑2.00.

Malayaite Ceramic Pigments Prepared from Industrial Wastes: Formulation and Characterization

2010 ◽  
Vol 636-637 ◽  
pp. 1371-1376 ◽  
Author(s):  
Ana Ribeiro ◽  
W. Hajjaji ◽  
M.P. Seabra ◽  
J.A. Labrincha
Keyword(s):  
Synthesis Temperature ◽  
Industrial Wastes ◽  
Lead Free ◽  
X Ray Diffraction ◽  
X Ray ◽  
Colour Measurements ◽  
Vis Spectroscopy ◽  
The Common ◽  
The Stability ◽  
Cielab Colour

In this work chrome-tin red malayaite pigments Ca(Cr,Sn)SiO5 were obtained from industrial wastes: a marble sawing sludge, a galvanizing sludge from the Cr/Ni process and a foundry sand. The pigments were prepared using the common solid state reaction process. The influence of Cr2O3/SnO2 ratio, calcination temperature and introduced sludges compositions, on its structural stability, was investigated by X-ray diffraction coupled with SEM/EDS. Standard formulations, obtained from commercial reagents, were also prepared and characterized for sake of comparison. CIELab colour measurements and UV-Vis spectroscopy were used to evaluate the stability (thermal and chemical) and applicability of the synthesized pigments in colouring distinct ceramic matrixes fired at high temperatures (1050°C-1200°C). The pigment was added (1/20 wt. ratio) to a transparent and shining lead free glaze and to a porcelain stoneware body (1/10 wt. ratio). The incorporation of three industrial wastes, in the chrome-tin red malayaite pigment, was possible without a notorious change in terms of colouring effect allowing decreasing the synthesis temperature.

scholarly journals Structural and Morphological Evaluation of 25% vol. Ni/Al2O3 Nanocomposite Powders Produced by Mechanical Milling

2015 ◽  
Vol 13 ◽  
pp. 48-53 ◽  
Author(s):  
Cristina Voicu ◽  
Florin Popa ◽  
Petru Pascuta ◽  
Ionel Chicinaş
Keyword(s):  
Milling Time ◽  
X Ray Diffraction ◽  
Composite Powders ◽  
Sem Images ◽  
X Ray ◽  
Morphological Evaluation ◽  
Two Phases ◽  
The Stability ◽  
High Level ◽  
Nanocomposite Powders

The evolution of the Al2O3/Ni (25% vol. Ni) composite powders, during the milling and the stability of the composite phases were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis (EDX). SEM images show a high level of homogenization of the Ni and Al2O3 phases for milling times larger than 120 minutes. The X-ray study indicates no reaction between the two phases. The crystallite grain size decreases with the milling time for both phases.

Structure determination of a new cocrystal of carbamazepine and DL-tartaric acid by synchrotron powder X-ray diffraction

2020 ◽  
Vol 76 (3) ◽  
pp. 225-230 ◽  
Author(s):  
Mathieu Guerain ◽  
Patrick Derollez ◽  
Luisa Roca-Paixão ◽  
Catherine Dejoie ◽  
Natália T. Correia ◽  
...  
Keyword(s):  
Tartaric Acid ◽  
Structural Model ◽  
European Synchrotron Radiation Facility ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Pxrd Pattern ◽  
X Ray ◽  
Monte Carlo Simulated Annealing ◽  
The Stability ◽  
Dynamics Simulations

The crystal structure of a new cocrystal of carbamazepine (systematic name: 5H-dibenzo[b,f]azepine-5-carboxamide, C15H12N2O) and DL-tartaric acid (C4H6O6), obtained by liquid-assisted grinding, was solved by powder X-ray diffraction (PXRD). The high-resolution PXRD pattern of this new phase was recorded at room temperature thanks to synchrotron experiments at the European Synchrotron Radiation Facility (Grenoble, France). The starting structural model was generated by a Monte-Carlo simulated annealing method. The final structure was obtained through Rietveld refinement and an energy minimization simulation was used to estimate the H-atom positions. The stability of the proposed structure as a function of temperature was also assessed from molecular dynamics simulations. The symmetry is monoclinic (space group P21/c) and contains eight molecules per unit cell, namely, four DL-tartaric acid and four carbamazepine molecules.

Synthesis, characterization and crystal structure of 4-methoxybenzylidene-based zinc(II) complexes

2022 ◽  
Vol 0 (0) ◽  
Author(s):  
Adrienne Ndiolene ◽  
Tidiane Diop ◽  
Ndiak Ndiaye ◽  
Mouhamadou Sembene Boye ◽  
François Michaud ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Infrared Spectroscopy ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Intermolecular Hydrogen Bonds ◽  
Space Group ◽  
X Ray ◽  
Type C ◽  
The Stability ◽  
Cl Atoms

Abstract Two novel zinc(II) complexes containing 4-methoxybenzylidene moieties namely, Zn(L)Cl2 (L = N, N′-bis(4-methoxybenzylidene)ethane-1, 2-diamine (1) or N-(4-methoxybenzylidene)-ethane-1, 2-diamine (2)) have been synthesized and characterized by infrared spectroscopy and single-crystal X-ray diffraction. Complex 1 crystallizes in the monoclinic space group P21/c with a = 9.2315(4); b = 12.0449(4); c = 18.2164(7) Å; β = 98.472(4)°, V = 1278.9(4) Å3 and Z = 4. Complex 2 crystallizes in the monoclinic space group P21/n with a = 6.5733 (2), b = 13.6595(5), c = 15.1615(5) Å; β = 101.846(4)°, V = 1332.33(8) Å3 and Z = 4. The environment of each Zn(II) atom is distorted tetrahedral with coordination of two terminal Cl atoms and two N atoms of the N,N′ – bis(4-methoxybenzylidene)ethane-1,2-diamine (1) or N-(4-methoxybenzylidene)ethane-1,2-diamine (2) ligand. The stability of the crystalline structure is ensured by the existence of intra- and intermolecular hydrogen bonds of the type C–H…Cl (1) and N–H…Cl (2) leading to supramolecular topologies.

Crystal structure of a new polyoxometalate (POM) compound with a high level of crystallographic disorder

2020 ◽  
Vol 76 (2) ◽  
pp. 164-169
Author(s):  
Eliska Skorepova ◽  
Ali Harchani ◽  
Mohamed Mongi Ftini ◽  
Michal Dušek ◽  
Amor Haddad
Keyword(s):  
Crystal Structure ◽  
Surface Analysis ◽  
Dominant Role ◽  
Hirshfeld Surface ◽  
Hirshfeld Surface Analysis ◽  
Spectroscopic Techniques ◽  
X Ray Diffraction ◽  
The Stability ◽  
High Level ◽  
Crystallographic Disorder

The crystal structure, Hirshfeld surface analysis and spectroscopic analysis of a new polyoxometalate (POM) compound, namely, nonakis(2-methoxyaniline) bis(diphosphopentamolybdate) trihydrate, (C7H9NO)9[P2Mo5O23]2·3H2O, is reported. The title compound was synthesized using the solution method and was structurally characterized by single-crystal X-ray diffraction, which revealed P\overline{1} symmetry. A study of the intermolecular interactions using Hirshfeld surface analysis confirmed that the hydrogen-bonding interactions play the dominant role in the stability of the crystal structure. The refinement was complicated by extensive disorder affecting 11 of the 16 ions and molecules in the asymmetric unit. IR and UV–Vis spectroscopic techniques were used to identify the vibrational modes and to classify this compound as an insulator.

Influence of Milling Time on the Homogeneity of the Al2O3/Ni Composite Powders Obtained by Mechanical Milling

2014 ◽  
Vol 216 ◽  
pp. 146-150 ◽  
Author(s):  
Cristina Voicu ◽  
Florin Popa ◽  
Petru Pascuta ◽  
Ionel Chicinaş
Keyword(s):  
Mechanical Milling ◽  
Milling Time ◽  
High Energy ◽  
X Ray Diffraction ◽  
Nanocomposite Powder ◽  
Composite Powders ◽  
X Ray ◽  
Two Phases ◽  
The Stability ◽  
High Level

Al2O3/Ni nanocomposite powder was obtained by high-energy mechanical milling starting from a mixture of Al2O3 and Ni commercially powders. The Al2O3+15%vol. Ni mixture was homogenized for 15 minutes in the Turbula-type blender and then was milled in a planetary ball mill (Fritsch, Pulverisette 4) under argon atmosphere up to 120 min. Several milling times were used: 10, 30, 60, 90 and 120 minutes respectively. The evolution of the powders during milling and the stability of the composite phases were investigated by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis (EDX). The SEM and OM images show a high level of homogenization of the Ni and Al2O3 phases for milling times larger than 90 minutes. The X-ray studies indicate no mixing between the two phases. The crystallite grain size is decreasing with the milling time.

Middlebackite, a new Cu oxalate mineral from Iron Monarch, South Australia: Description and crystal structure

2018 ◽  
Vol 83 (03) ◽  
pp. 427-433 ◽  
Author(s):  
Peter Elliott
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
South Australia ◽  
Monoclinic Space Group ◽  
Formula Unit ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
X Ray ◽  
Perfect Cleavage ◽  
Mohs Hardness

AbstractMiddlebackite is a new supergene mineral formed in the upper levels of the Iron Monarch quarry, South Australia. It occurs as aggregates of blue, prismatic crystals up to 0.3 mm across comprising individual crystals up to 0.05 mm in length associated with atacamite and mottramite. Crystals are translucent with a vitreous lustre and have a pale blue streak. Middlebackite is brittle with one perfect cleavage and uneven fracture. Mohs hardness is ~2. The calculated density is 3.64 g cm–3. Crystals are biaxial (+) with α = 1.663(4), β = 1.748(4) and γ = 1.861(4) (measured in white light). The calculated 2V is 86.7°. Pleochroism isX= colourless,Y= very pale blue andZ= dark sky blue;Z&gt;Y&gt;X. The empirical formula unit, based on six oxygen atoms per formula unit is Cu2.00(C2O4)Cl0.02(OH)1.98. Middlebackite is monoclinic, space groupP21/c witha= 7.2597(15),b= 5.7145(11),c= 5.6624(11) Å, β = 104.20(3)°,V= 227.73(8) Å3andZ= 2. The five strongest lines in the powder X-ray diffraction pattern are [d(Å), (I), (hkl)]: 7.070 (16) (100), 3.739 (100) (11$\bar{1}$), 2.860 (18) (020), 2.481 (12) (12$\bar{1}$) and 2.350 (9) (300). The crystal structure was refined from synchrotron single-crystal X-ray diffraction data toR1= 0.0341 for 596 observed reflections withF0&gt; 4σ(F0). The structure is based on sheets of edge- and corner-sharing octahedra parallel to thebcplane. Sheets link in theadirection via oxalate anions.

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