scholarly journals Structure Analysis of Natural Wangdaodeite—LiNbO3-Type FeTiO3

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1072
Author(s):  
Oliver Tschauner ◽  
Chi Ma ◽  
Matthew G. Newville ◽  
Antonio Lanzirotti
Keyword(s):  
Raman Spectrum ◽  
Structure Analysis ◽  
Structure Refinement ◽  
Unit Cell ◽  
Type Material ◽  
Raman Peak ◽  
Impact Structure ◽  
Structure Comparison ◽  
Peak Shock ◽  
Natural And Synthetic

This paper reports the first structure refinement of natural wangdaodeite, LiNbO3-type FeTiO3 from the Ries impact structure. Wangdaodeite occurs together with recrystallized ilmenite clasts in shock melt veins which have experienced peak shock pressures of between 17 and 22 GPa. Comparison of natural and synthetic wangdaodeite points toward a correlation between the distortion of ferrate- and titanate-polyhedra and the c/a ratio of the unit cell. The Raman spectrum of wangdaodeite is calculated based on the refined structure. Comparison to the reported spectrum of the type-material shows that the Raman peak at 738–740 cm−1 is indicative for this phase, whereas other features in type-wangdaodeite are tentatively assigned to disordered ilmenite.

X-ray Structure Refinement and Vibrational Spectroscopy of Ca8Gd2 (PO4)6 O2

2013 ◽  
Vol 12 (10) ◽  
pp. 719-726
Author(s):  
R. Ayadi ◽  
Mohamed Boujelbene ◽  
T. Mhiri
Keyword(s):  
Solid State ◽  
General Formula ◽  
Vibrational Spectroscopy ◽  
Powder Diffraction ◽  
Infrared Spectra ◽  
Solid State Reaction ◽  
Structure Refinement ◽  
Unit Cell ◽  
Cell Group ◽  
X Ray

The present paper is interested in the study of compounds from the apatite family with the general formula Ca10 (PO4)6A2. It particularly brings to light the exploitation of the distinctive stereochemistries of two Ca positions in apatite. In fact, Gd-Bearing oxyapatiteCa8 Gd2 (PO4)6O2 has been synthesized by solid state reaction and characterized by X-ray powder diffraction. The site occupancies of substituents is0.3333 in Gd and 0.3333 for Ca in the Ca(1) position and 0. 5 for Gd in the Ca (2) position.  Besides, the observed frequencies in the Raman and infrared spectra were explained and discussed on the basis of unit-cell group analyses.

The crystal chemistry of the uranyl carbonate mineral grimselite, (K, Na)3Na[(UO2)(CO3)3](H2O), from Jáchymov, Czech Republic

2012 ◽  
Vol 76 (3) ◽  
pp. 443-453 ◽  
Author(s):  
J. Plášil ◽  
K. Fejfarová ◽  
R. Skála ◽  
R. Škoda ◽  
N. Meisser ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Czech Republic ◽  
Structure Refinement ◽  
Unit Cell ◽  
Carbonate Mineral ◽  
X Ray Diffraction ◽  
The Czech Republic ◽  
Cell Parameters ◽  
Uranyl Carbonate ◽  
Diffraction Peaks

AbstractTwo crystals of the uranyl carbonate mineral grimselite, ideally K3Na[(UO2)(CO3)3](H2O), from Jáchymov in the Czech Republic were studied by single-crystal X-ray diffraction and electron-probe microanalysis. One crystal has considerably more Na than the ideal chemical composition due to substitution of Na into KO8 polyhedra; the composition of the other crystal is nearer to ideal, and similar to synthetic grimselite. The presence of Na atoms in KO8 polyhedra, which are located in channels in the crystal structure, reduces their volume, and as a result the unit-cell volume also decreases. Structure refinement shows that the formula for the sample with the anomalously high Na content is (K2.43Na0.57)Σ3.00Na[(UO2)(CO3)3](H2O). The unit-cell parameters, refined in space group P2c, are a = 9.2507(1), c = 8.1788(1) Å, V = 606.14(3) Å3 and Z = 2. The crystal structure was refined to R1 = 0.0082 and wR1 = 0.0185 with a GOF = 1.33, based on 626 observed diffraction peaks [Iobs>3σ(I)].

Primäre und sekundäre Ethyl-und i-Propylsulfoniumsalze sowie Kristallstruktur von i-C3H7SH2+SbF6- [1]

1996 ◽  
Vol 51 (2) ◽  
pp. 277-285
Author(s):  
Rolf Minkwitz ◽  
Ulrike Lohmann ◽  
Hans Preut
Keyword(s):  
Crystal Structure ◽  
Structure Analysis ◽  
Bond Distance ◽  
Crystal Structure Analysis ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Spectroscopic Methods ◽  
Sulfonium Salt ◽  
Space Group

Abstract The synthesis of salts of the type RnSH3-n+MF6- (R = C2H5, i-C3H7; n = 1, 2; M = As, Sb) by protonation of the corresponding thiols and sulfides in the superacid systems HF/MF5 is reported. The salts have been characterized by vibrational and NMR spectroscopic methods. Isopropylsulfonium hexafluoroantimonate is the first known example of a sulfonium salt, for which a SH bond distance has been determined by a crystal structure analysis, i-C3H7SH2+SbF6- crystallizes in the monoclinic space group P21/m with a = 568.0(4), b = 801.1(6), c = 1019.7(8) pm, β = 82.63(6) °, with two formula units per unit cell.

Reexamination of the crystal structure of semseyite, Pb9Sb8S21

2018 ◽  
Vol 233 (3-4) ◽  
pp. 279-284 ◽  
Author(s):  
Yoshitaka Matsushita
Keyword(s):  
Crystal Structure ◽  
Chemical Composition ◽  
Single Crystal ◽  
Structure Refinement ◽  
Unit Cell ◽  
Crystal Structure Refinement ◽  
Cell Level ◽  
Single Crystal Specimen ◽  
Cation Sites ◽  
Occupancy Behavior

AbstractThe crystal structure of semseyite, Pb9Sb8S21was successfully refined using a single-crystal specimen from Wolfsberg, Harz, Germany, having chemical composition (EPMA) Pb9.01(1)Sb8.00(3)S21.05(5). The structure belongs to the monoclinicC2/cspace group (a=13.6267(10) Å,b=11.9742(9) Å,c=24.5891(18) Å,β=105.997(3)°,V=3856.8(5) Å3,Z=4,Dc=6.048 g/cm3). Crystal structure refinement with all atoms refined anisotropically converged toR1=4.64% (I>2σ(I)). The crystal structure is built of two subunits (A and B) showing TlSbS2-like topology. Each of them stacks parallel to (001), andc/2 in thickness. Two cation sites (Pb1 and Sb5) located at central part of the subunit, show mixed occupancy behavior as 95% Pb and 5% Sb at the Pb5 site, and 95% Sb and 5% Pb at the Sb1 site, respectively. Each of subunits are related by unit cell-level twinning mechanism “tropochemical cell twinning” with the TlSbS2-like subunits alternatively parallel to (1 1 −4) and (−1 1 4) planes.

Structure Analysis of a Rodlike Macromolecule: Poly(2,2'-(p,p'-Biphenyl)−6,6'-bis(4-Phenylquinoline))

1988 ◽  
Vol 134 ◽  
Author(s):  
Craig W. Burkhart ◽  
Jerome B. Lando ◽  
John K. Stille
Keyword(s):  
Crystal Structure ◽  
Structure Analysis ◽  
Molecular Packing ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fiber Diffraction ◽  
Herringbone Structure ◽  
Packing Analysis

ABSTRACTUniaxially oriented, crystalline fibers of poly(2,2'-(p,p'-biphenyl)- 6,6'-bis(4-phenylquinoline)) [PBPQ], were subjected to structure analysis via x-ray diffraction and molecular packing analysis. Packing analysis was required due to the sparse and diffuse nature of the fiber diffraction photographs. The combination of the two techniques allowed us to resolve the crystal structure. PBPQ packs in a syn conformation, in a modified herringbone structure. It has a unit cell of a = 16.2Å, b = 5.31Å, c = 21.4Å. There are two independent chains in the unit cell. An overview of the refinement of the crystal structure, the packing analysis and the crystallography are presented.

scholarly journals Structure analysis of an Fe-interlayer expanded zeolite.

2014 ◽  
Vol 70 (a1) ◽  
pp. C186-C186
Author(s):  
Hermann Gies ◽  
Mathias Feyen
Keyword(s):  
Structure Analysis ◽  
Active Sites ◽  
Hydrothermal Reaction ◽  
Uv Spectroscopy ◽  
Structure Refinement ◽  
Rietveld Analysis ◽  
Active Centers ◽  
Layer Silicates ◽  
New Material ◽  
Silicate Layers

Interlayer expansion using silylating agents to connect layer silicates to 3D framework structures has proofed to be a versatile synthesis route to new micro-porous frameworks (1). We show here that also Me-cations can be used as linker agents. An acidic Fe-chloride solution was used in a hydrothermal reaction to convert the hydrous layer silicate RUB-36 into an interlayer expanded zeolite, containing Fe at the linker site. Structure analysis of the new material Fe-COE-3, Si19.14Fe0.86O42, showed that the porous framework is stable after calcination and contains Fe on T-sites at the linker position which connects the two silicate layers. From chemical analysis it is confirmed that every other linker site is occupied by iron. The material crystallizes in space group Pm with a = 12.200(9) Å, b = 13.981(8) Å, c = 7.369(2) Å, ß = 106.9(1)0. Fig. 1 shows the results of the final Rietveld analysis (chi2= 8.8) and a projection of the framework structure along [001]. Because of the limited crystallinity of the material also the quality of the structure refinement is constricted. However, including complementary information from adsorption experiments, IR-, and UV-spectroscopy the structure model is confirmed without any doubt. Besides, the Rietveld analysis of the XRD data is the analytical tool to gain more detailed geometric information of the metallosilicate framework. The synthesis procedure is flexible and can be extended to other Me-cations as linker sites. We have prepared isostructural interlayer expanded metallosilicates of similar crystallinity with Ti, Sn, Zn, Eu, and Al as active centers. This method of inserting Me-cations as linkers in hydrous layer silicates shows for the first time that the active sites in the generated microporous silicate framework can be obtained in a controlled manner on well defined T-sites.

X-Ray Analysis of the Cd0.5Ge0.5Cr2Se4 and CdCr1.9Ge0.075Se4 Compounds

2007 ◽  
Vol 130 ◽  
pp. 93-96
Author(s):  
Ewa Maciążek ◽  
Tomasz Goryczka ◽  
Izabela Jendrzejewska
Keyword(s):  
Structure Analysis ◽  
Spinel Structure ◽  
Rietveld Method ◽  
Spinel Phase ◽  
Structure Refinement ◽  
Ceramic Method ◽  
X Ray ◽  
Normal Spinel

The polycrystalline Cd0.5Ge0.5Cr2Se4 and CdCr1.9Ge0.075Se4 compounds were obtained using ceramic method. X-ray analysis was used to make phase and structure analysis. The Rietveld method was applied for structure refinement. Both compounds crystallized in cubic, normal spinel structure, Fd 3m. Besides the main spinel phase, Cr2Se3 was observed.

scholarly journals Powder XRD Structural Study of Ba2+ Modified Clinoptilolite at Different Stages of the Ion Exchange Process Conducted at Two Temperature Regimes—Room Temperature and 90 °C

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 938
Author(s):  
Louiza Dimowa ◽  
Yana Tzvetanova ◽  
Ognyan Petrov ◽  
Iskra Piroeva ◽  
Filip Ublekov
Keyword(s):  
Ion Exchange ◽  
Room Temperature ◽  
Structure Refinement ◽  
Exchange Process ◽  
Unit Cell ◽  
Powder Xrd ◽  
Ion Exchange Process ◽  
Temperature Regimes ◽  
Intensity Changes ◽  
Modified Clinoptilolite

Partial and almost complete barium exchange on clinoptilolite is performed and structurally studied for different durations (2 h, 24 h, 72 h, 168 h, 12 d, 22 d) at room temperature and 90 °C of the ion exchange process. Continuing ion exchange up to the 22nd day is proved by EDS analyses data and powder XRD (intensity changes of 020 and 200 peaks). Rietveld structure refinement was first performed on the maximum Ba exchanged clinoptilolite at 90 °C for 22 days (3.04 atoms per unit cell). Four barium positions and 9 H2O sites were refined. The split positions Ba2 and BaK (around M3 site in channel C) were found mostly occupied by 2.23 atoms per unit cell. The rest of refined samples showed different occupations of the positions of incoming Ba2+ and outgoing cations (Na+, Ca2+, K+, Mg2+) during ion exchange, describing extra-framework cationic movements, which are released easily without preferable directions. The exchanges at 90 °C and room temperature were found proceeding similarly up to the 2nd hour, but then at room temperature the process is slowed and at 22nd day 1.64 barium atoms per unit cell are structurally refined.

The X-Ray Studies and Magnetic Properties of Co0.83Fe1.8Se4

2010 ◽  
Vol 163 ◽  
pp. 213-216
Author(s):  
Ewa Maciążek ◽  
Tomasz Goryczka ◽  
Jerzy Mroziński ◽  
Izabela Jendrzejewska ◽  
Beata Zawisza
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Chemical Composition ◽  
Structure Analysis ◽  
Rietveld Method ◽  
Structure Refinement ◽  
Energy Dispersive ◽  
Monoclinic System ◽  
Ceramic Method ◽  
X Ray

The polycrystalline Co0.83Fe1.8Se4 compound was obtained using ceramic method. The chemical composition was verified using energy-dispersive X-ray fluorescence spectrometry (EDXRF) and EDS method. X-ray analysis was used to make phase and structure analysis. The Rietveld method was applied for structure refinement. Co0.83Fe1.8Se4 compound crystallized in monoclinic system, space group C . The magnetic susceptibility and magnetization were measured, they revealed ferrimagnetic properties of a sample.

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