Magnetic behaviour of trioctahedral mica-2M1 occurring in a magnetic anomaly zone

2008 ◽  
Vol 72 (5) ◽  
pp. 1035-1042 ◽  
Author(s):  
S. Pini ◽  
M. Affronte ◽  
M. F. Brigatti
Keyword(s):  
Magnetic Susceptibility ◽  
Peak Position ◽  
Magnetic Behaviour ◽  
Ac Magnetic Susceptibility ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Trioctahedral Mica ◽  
Two Peaks ◽  
X Ray Absorption

AbstractThis work relates the crystal chemistry and the magnetic behaviour of a trioctahedral mica (chemical formula: (K0.90Na0.01Ca0.01Ba0.01 ☐0.07)(Al0.05Fe2+1.10Mg1.38Ti0.32Mn0.01☐0.04)(Al1.12Si2.88)O10 (F0.27OH1.27O0.46); unit cell parameters: a = 5.345(2) Å, b = 9.261(4) Å, c = 20.189(8) Å; β = 95.075(8)°) from Minto Block (Ungava peninsula, northern Quebec, Canada), a region characterized by high magnetic anomalies. Crystallographic and X-ray absorption spectroscopy data suggest a prevalent divalent oxidation state for Fe and a disordered Fe 2+ distribution in the two octahedral sites Ml and M2. The real part of magnetic susceptibility shows two peaks at ∼5.2 K and 120 K. However, as demonstrated by AC magnetic susceptibility measurements, the origin of the two effects is different: the peak position of the first one (i.e. the effect revealed at 5.2 K) is frequency-dependent, thus suggesting a spin-glass like behaviour. The effect at 120 K can instead be attributed to the occurrence of diluted phases in mica matrix, such as Fe oxides.

XRD and EXAFS studies of azomethynic copper metallochelates as models of blue copper proteins

2004 ◽  
Vol 19 (3) ◽  
pp. 225-231 ◽  
Author(s):  
V. G. Vlasenko ◽  
A. T. Shuvaev ◽  
A. L. Nivorozkin ◽  
A. I. Uraev
Keyword(s):  
Copper Complexes ◽  
Copper Proteins ◽  
Blue Copper Proteins ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Lattice Space ◽  
Monoclinic Lattice ◽  
Ray Patterns ◽  
X Ray Absorption

The structure of two biomimetic copper complexes bis[4-benzylaldimino-3-methyl-1-phenyl-5-thio (seleno)pyrazolato]copper(II)—36 32N6X2Cu (where X=S, Se) have been studied and X-ray patterns of these compounds have been prepared using the Rietveld refinement technique. Both complexes crystallized in a monoclinic lattice, space group-C2/c(15). The unit-cell parameters are a=28.917(3) Å; b=7.000(2) Å; c=17.550(4) Å; β=106.869(1) (1) for C36H32CuN6S2 and a=29.126(6) Å; b=7.042(4) Å; c=17.228(2) Å; β=105.587(2) for C36H32CuN6Se2. Analysis of the copper and selenium K-edge X-ray absorption spectra (EXAFS) of these complexes show that a copper atom is in pseudo-tetrahedric ligand environment N2X2 with typical Cu–N bonds (R=2.00–2.01 Å) and significantly different Cu–S and Cu–Se bonds (R=2.27 Å and R=2.41 Å, respectively) because of different sulfur and selenium ion radii. © 2004 International Centre for Diffraction Data.

scholarly journals INCORPORATION OF Mo6+ IN FERRIHYDRITE, GOETHITE, AND HEMATITE

2021 ◽  
Author(s):  
Marcel G. Görn ◽  
Ralph M. Bolanz ◽  
Stephen Parry ◽  
Jörg Göttlicher ◽  
Ralph Steininger ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Structural Disorder ◽  
Unit Cell ◽  
Emission Spectrometry ◽  
Charge Balance ◽  
Unit Cell Parameters ◽  
Edge Structure ◽  
X Ray ◽  
Cell Parameters ◽  
X Ray Absorption

AbstractAmong all iron oxides, hematite (α-Fe2O3), goethite (α-FeOOH), and ferrihydrite (FeOOH⋅nH2O) are the most common mineral species. While immobilization of Mo6+ by surface adsorption on ferric oxides has been studied extensively, the mechanisms of incorporation in their structure have been researched little. The objective of this study was to investigate the relation between Mo content and its structural incorporation in hematite, goethite, and six-line ferrihydrite by a combination of X-ray absorption spectroscopy (XAS), powder X-ray diffraction (pXRD), and inductively-coupled plasma optical emission spectrometry (ICP-OES). Synthesized in the presence of Mo, the hematite, goethite, and six-line ferrihydrite phases incorporated up to 8.52, 0.03, and 17.49 wt. % Mo, respectively. For hematite and goethite, pXRD analyses did not indicate the presence of separate Mo phases. Refined unit-cell parameters correlated with increasing Mo concentration in hematite and goethite. The unit-cell parameters indicated an increase in structural disorder within both phases and, therefore, supported the structural incorporation of Mo in hematite and goethite. Analysis of pXRD measurements of Mo-bearing six-line ferrihydrites revealed small amounts of coprecipitated akaganéite. X-ray absorption near edge structure (XANES) measurements at the Mo L3-edge indicated a strong distortion of the MoO6 octahedra in all three phases. Fitting of extended X-ray absorption fine structure (EXAFS) spectra of the Mo K-edge supported the presence of such distorted octahedra in a coordination environment similar to the Fe position in the investigated specimen. Incorporation of Mo6+ at the Fe3+-position for both hematite and goethite resulted in the formation of one Fe vacancy in close proximity to the newly incorporated Mo6+ and, therefore, charge balance within the hematite and goethite structures.

scholarly journals The Oxidation State and Magnetic Behaviour of Tb in High-Tc Related Materials

1994 ◽  
Vol 376 ◽  
Author(s):  
L. Soderholm ◽  
U. Staub ◽  
S. Skanthakumar ◽  
M. R. Antonio
Keyword(s):  
Magnetic Susceptibility ◽  
Oxidation State ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Magnetic Behaviour ◽  
Magnetic Interactions ◽  
High Tc ◽  
X Ray ◽  
Long Range Ordering ◽  
X Ray Absorption

ABSTRACTL3-x-ray absorption spectroscopy is used together with inelastic neutron scattering and magnetic susceptibility measurements to characterize the Tb oxidation state and bonding in the high-Tc related materials Y1-xTbxBa2Cu3O7 and Pb2Sr2TbCu3O8. The Tb is found to be essentially trivalent in both compounds with no indications of significant hybridization. However, there is evidence of significant Tb-Tb magnetic interactions in Pb2Sr2TbCu3O8 that persist to temperatures much higher than the Tb long-range ordering temperature.

H2/N2 MIXTURE ATMOSPHERE EFFECTS ON THE BEHAVIOR OF THE DOUBLE PEROVSKITE COMPOUND Sr2CoMoO6

2008 ◽  
Vol 22 (21) ◽  
pp. 3579-3588 ◽  
Author(s):  
A. AZIZI ◽  
A. KAHOUL ◽  
G. SCHMERBER ◽  
S. COLIS ◽  
A. DINIA
Keyword(s):  
Magnetic Susceptibility ◽  
Solid State ◽  
Solid State Reaction ◽  
Room Temperature ◽  
Double Perovskite ◽  
Gas Mixture ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters

Sr 2 CoMoO 6 and Sr 2 CoMoO 6-δ ceramics have been obtained by solid state reaction in air and in a H 2/ N 2 gas mixture. At room temperature, as shown by X-ray diffraction, both compounds have a tetragonal perovskite-like structure with doublet unit-cell parameters, space group I4/m, with a = 5.5575, c = 7.9342 in Sr 2 CoMoO 6 and a = 5.5683 and c = 7.9395 in Sr 2 CoMoO 0.95. The latter contains small traces of Co and SrCoO 2.61, with an almost expansion. The magnetic susceptibility indicates that Sr 2 CoMoO 6 is an antiferromagnet with TN = 37 K. The magnetization was found to be the same in both samples, while the electric properties, originating from the oxygen content, are drastically affected.

Structural Study of a new Compound Based on Acid 1,4-Cyclohexanedicarboxylic (1,4-CDC)

2010 ◽  
Vol 6 (1) ◽  
pp. 891-896
Author(s):  
Manel Halouani ◽  
M. Dammak ◽  
N. Audebrand ◽  
L. Ktari
Keyword(s):  
Aqueous Solution ◽  
Water Molecules ◽  
Carboxyl Group ◽  
X Ray Diffraction ◽  
Compound I ◽  
Unit Cell Parameters ◽  
Monoclinic System ◽  
X Ray ◽  
Cell Parameters ◽  
Cyclohexanedicarboxylic Acid

One nickel 1,4-cyclohexanedicarboxylate coordination polymers, Ni2 [(O10C6H4)(COO)2].2H2O  (I), was hydrothermally synthesized from an aqueous solution of Ni (NO3)2.6H2O, (1,4-CDC) (1,4-CDC = 1,4-cyclohexanedicarboxylic acid) and tetramethylammonium nitrate. Compound (I) crystallizes in the monoclinic system with the C2/m space group. The unit cell parameters are a = 20.1160 (16) Å, b = 9.9387 (10) Å, c = 6.3672 (6) Å, β = 97.007 (3) (°), V= 1263.5 (2) (Å3) and Dx= 1.751g/cm3. The refinement converged into R= 0.036 and RW = 0.092. The structure, determined by single crystal X-ray diffraction, consists of two nickel atoms Ni (1) and Ni (2). Lots of ways of which is surrounded by six oxygen atoms, a carboxyl group and two water molecules.

scholarly journals Crystallization and preliminary X-ray diffraction analysis of the Csu pili CsuC–CsuA/B chaperone–major subunit pre-assembly complex fromAcinetobacter baumannii

2015 ◽  
Vol 71 (6) ◽  
pp. 770-774 ◽  
Author(s):  
Natalia Pakharukova ◽  
Minna Tuittila ◽  
Sari Paavilainen ◽  
Anton Zavialov
Keyword(s):  
Diffusion Method ◽  
X Ray Diffraction ◽  
Hanging Drop ◽  
Unit Cell Parameters ◽  
Gram Negative ◽  
X Ray ◽  
Cell Parameters ◽  
Abiotic Surfaces ◽  
Vapour Diffusion ◽  
Fimbrial Adhesins

The attachment of many Gram-negative pathogens to biotic and abiotic surfaces is mediated by fimbrial adhesins, which are assembledviathe classical, alternative and archaic chaperone–usher (CU) pathways. The archaic CU fimbrial adhesins have the widest phylogenetic distribution, yet very little is known about their structure and mechanism of assembly. To elucidate the biogenesis of archaic CU systems, structural analysis of the Csu fimbriae, which are used byAcinetobacter baumanniito form stable biofilms and cause nosocomial infection, was focused on. The major fimbriae subunit CsuA/B complexed with the CsuC chaperone was purified from the periplasm ofEscherichia colicells co-expressing CsuA/B and CsuC, and the complex was crystallized in PEG 3350 solution using the hanging-drop vapour-diffusion method. Selenomethionine-labelled CsuC–CsuA/B complex was purified and crystallized under the same conditions. The crystals diffracted to 2.40 Å resolution and belonged to the hexagonal space groupP6422, with unit-cell parametersa=b= 94.71,c = 187.05 Å, α = β = 90, γ = 120°. Initial phases were derived from a single anomalous diffraction (SAD) experiment using the selenomethionine derivative.

Silicate-germanate K2Y[(Si3Ge)O10(OH)] with unusual complex corrugated layer and its correlation to ring silicate gerenite and chain silicate chkalovite

2020 ◽  
Vol 235 (4-5) ◽  
pp. 167-172
Author(s):  
Anastasiia P. Topnikova ◽  
Elena L. Belokoneva ◽  
Olga V. Dimitrova ◽  
Anatoly S. Volkov ◽  
Leokadiya V. Zorina
Keyword(s):  
Low Temperature ◽  
Cross Section ◽  
Complex Anion ◽  
Diffraction Experiment ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Chain Silicate ◽  
Novel Complex

AbstractA new silicate-germanate K2Y[(Si3Ge)O10(OH)] was synthesized hydrothermally in a system Y2O3:GeO2:SiO2 = 1:1:2 (T = 280 °C; P = 90–100 atm.); K2CO3 was added to the solution as a mineralizer. Single-crystal X-ray diffraction experiment was carried out at low temperature (150 K). The unit cell parameters are a = 10.4975(4), b = 6.9567(2), c = 15.4001(6) Å, β = 104.894(4)°; V = 1086.86(7) Å3; space group is P 21/c. A novel complex anion is presented by corrugated (Si,Ge) tetrahedral layers connected by couples of YO6 octahedra into the mixed microporous framework with the channels along b and a axes, the maximal size of cross-section is ~5.6 Å. This structure has similarity with the two minerals: ring silicate gerenite (Ca,Na)2(Y,REE)3Si6O18 · 2H2O and chain silicate chkalovite Na2BeSi2O6. Six-member rings with 1̅ symmetry as in gerenite are distinguished in the new layer. They are mutually perpendicular to each other and connected by additional tetrahedra. Straight crossing chains in chkalovite change to zigzag four-link chains in the new silicate-germanate layer.

X-ray powder diffraction data of LaNi0.5Ti0.45Co0.05O3, LaNi0.45Co0.05Ti0.5O3, and LaNi0.5Ti0.5O3 perovskites

2021 ◽  
pp. 1-6
Author(s):  
Mariana M. V. M. Souza ◽  
Alex Maza ◽  
Pablo V. Tuza
Keyword(s):  
Crystal Structure ◽  
Rietveld Method ◽  
Pechini Method ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Modified Pechini Method ◽  
Scanning Electron

In the present work, LaNi0.5Ti0.45Co0.05O3, LaNi0.45Co0.05Ti0.5O3, and LaNi0.5Ti0.5O3 perovskites were synthesized by the modified Pechini method. These materials were characterized using X-ray fluorescence, scanning electron microscopy, and powder X-ray diffraction coupled to the Rietveld method. The crystal structure of these materials is orthorhombic, with space group Pbnm (No 62). The unit-cell parameters are a = 5.535(5) Å, b = 5.527(3) Å, c = 7.819(7) Å, V = 239.2(3) Å3, for the LaNi0.5Ti0.45Co0.05O3, a = 5.538(6) Å, b = 5.528(4) Å, c = 7.825(10) Å, V = 239.5(4) Å3, for the LaNi0.45Co0.05Ti0.5O3, and a = 5.540(2) Å, b = 5.5334(15) Å, c = 7.834(3) Å, V = 240.2(1) Å3, for the LaNi0.5Ti0.5O3.

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 Synthesis, purification and crystallographic studies of the C-terminal sterol carrier protein type 2 (SCP-2) domain of human hydroxysteroid dehydrogenase-like protein 2

2015 ◽  
Vol 71 (7) ◽  
pp. 901-905 ◽  
Author(s):  
Zhong Cheng ◽  
Yao Li ◽  
Chun Sui ◽  
Xiaobo Sun ◽  
Yong Xie
Keyword(s):  
Catalytic Domain ◽  
Hydroxysteroid Dehydrogenase ◽  
Carrier Protein ◽  
Sterol Carrier Protein ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Protein Molecules

Human hydroxysteroid dehydrogenase-like protein 2 (HSDL2) is a member of the short-chain dehydrogenase/reductase (SDR) subfamily of oxidoreductases and contains an N-terminal catalytic domain and a C-termianl sterol carrier protein type 2 (SCP-2) domain. In this study, the C-terminal SCP-2 domain of human HSDL2, including residues Lys318–Arg416, was produced inEscherichia coli, purified and crystallized. X-ray diffraction data were collected to 2.10 Å resolution. The crystal belonged to the trigonal space groupP3121 (orP3221), with unit-cell parametersa=b= 70.4,c= 60.6 Å, α = β = 90, γ = 120°. Two protein molecules are present in the asymmetric unit, resulting in a Matthews coefficient of 2.16 Å3 Da−1and an approximate solvent content of 43%.

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