scholarly journals Synthesis of isomorphically substituted Ru manganese molecular sieves and their catalytic properties for selective alcohol oxidation

2020 ◽  
Vol 8 (7) ◽  
pp. 3771-3784 ◽  
Author(s):  
Ferran Sabaté ◽  
José L. Jordá ◽  
María J. Sabater ◽  
Avelino Corma
Keyword(s):  
Manganese Oxide ◽  
Rietveld Refinement ◽  
Molecular Sieves ◽  
Catalytic Properties ◽  
Alcohol Oxidation ◽  
X Ray ◽  
Cell Parameters

Ruthenium has been incorporated into the framework of the cryptomelane type manganese oxide K-OMS-2 ([Ru]-K-OMS2). Accordingly, Rietveld refinement of the X-ray diffractogram has allowed to estimate changes in the values of cell parameters.

A powder diffraction study of MIBaIn2(PO4)3 (MI=Na, K, Cs) with a langbeinite-type structure

2002 ◽  
Vol 17 (1) ◽  
pp. 1-6 ◽  
Author(s):  
D. Louër ◽  
V. Moise ◽  
M. Liégeois-Duyckaerts ◽  
A. Rulmont
Keyword(s):  
Diffraction Study ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Type Structure ◽  
Monochromatic Radiation ◽  
Powder Diffraction Data ◽  
Asymmetric Unit ◽  
X Ray ◽  
Cell Parameters

Three phosphates, MIBaIn2(PO4)3 with MI=Na, K, Cs, isostructural to the langbeinite structure, have been studied from powder diffraction data collected with monochromatic radiation obtained from a conventional X-ray source. Precise powder data are reported, as well as cell parameters, i.e., a=10.026 08(9) Å, a=10.121 57(13) Å and a=10.226 94(9) Å for MI=Na, K and Cs, respectively. A Rietveld refinement has been carried out (space group P213), with final RF factors, 0.061, 0.041 and 0.027, and Rwp factors, 0.196, 0.142 and 0.129, for MI=Na, K and Cs, respectively. There are two octahedrally coordinated In3+ ions in the asymmetric unit and the final refinements suggest disorder on the two sites of the MI/Ba sublattice.

scholarly journals Synthesis and crystal structure of the quaternary semiconductor Cu2NiGeS4, a new stannite-type compound

2019 ◽  
Vol 65 (4 Jul-Aug) ◽  
pp. 355 ◽  
Author(s):  
G. E. Delgado ◽  
And V. Sagredo
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Quaternary Compound ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Cell Parameters

The crystal structure of the quaternary compound Cu2NiGeS4, belonging to the system I2-II-IV-VI4, was characterized by Rietveld refinement using X-ray powder diffraction data. This material crystallize with a stannite structure in the tetragonal space group I2m (Nº 121), Z = 2, unit cell parameters a = 5.3384(1) Å, c = 10.5732(3) Å, V = 301.32(3) Å3, acknowledged as a normal valence adamantane-structure.

scholarly journals Synthesis and Characterization of a New Aluminosilicate Molecular Sieve from Aluminosilica Perhydrate Hydrogel

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5469
Author(s):  
Haiqiang Ma ◽  
Kun Jiao ◽  
Xiangyu Xu ◽  
Jiaqing Song
Keyword(s):  
Molecular Sieves ◽  
Molecular Sieve ◽  
Critical Factor ◽  
Synthesis And Characterization ◽  
X Ray ◽  
Cell Parameters ◽  
Structure And Morphology ◽  
Novel Structure ◽  
Pure Phase

A novel structure aluminosilicate molecular sieve, named BUCT-3, was prepared by dynamic hydrothermal synthesis, and the critical factor to obtain the new structure is using an active silicon and aluminum source, aluminosilica perhydrate hydrogel. Meanwhile, only high content of O-O bonds can ensure the pure phase of BUCT-3. Through the characterization of x-ray powder diffraction (XRD), Fourier transform infrared spectra (FTIR), scanning electron microscopy (SEM), and so on, some structure and morphology information of BUCT-3 molecular sieves as well as the special silicon and aluminum source was obtained. It’s worth noticing that the O-O bonds of reactants can be reserved in the products, and thus, help us to get a new structure with cell parameters a = 8.9645 Å, b = 15.2727 Å, c = 11.3907 Å, α = 90°, β = 93.858°, γ = 90°. The crystal system is monoclinic. Though the thermostability of BUCT-3 is not satisfactory, its potential application derived from O-O bonds cannot be neglected.

XRD diffraction data and Rietveld refinement of Na8[Si6Al6O24]Cl2

2009 ◽  
Vol 24 (1) ◽  
pp. 41-43 ◽  
Author(s):  
Guilherme Oliveira Siqueira ◽  
Érica Gonçalves Gravina ◽  
Jackson Antônio Lamounier Camargos Resende ◽  
Nelson Gonçalves Fernandes
Keyword(s):  
Infrared Spectroscopy ◽  
Rietveld Refinement ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Alkaline Complex ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Xrd Diffraction ◽  
Bending Modes

A natural sodalite from the geological site Alkaline Complex of Floresta Azul, Bahia, Brazil, has been characterized by electron microprobe, infrared spectroscopy, and powder high-resolution X-ray diffraction techniques. The mineral is an aluminosilicate framework, formed by cages called sodalite unity. Although the sample is natural, the chemical analysis reveals that it is indeed the end member sodalite sensu strictu, Na8[Si6Al6O24]Cl2. Infrared spectroscopy shows Si, Al tetrahedral-oxygen stretching nonsymmetric mode, stretching symmetric mode, and bending modes. Indexing of the experimental X-ray diffraction pattern led to cubic space group P-43n, and unit-cell parameters: a=8.8767(7) Å, Dx=2.301 g cm−3, and V=699.46(1) Å3. X-ray diffraction data are reported. Rietveld refinement was also performed, and the confidence factors are Rp=0.079, Rwp=0.118, and χ2=2.19. The structure of the minerals of sodalite group holds four different tetrahedra: AlO4, ClNa4, Na(ClO3), and SiO4, with Al, Cl, Na, and Si located at the center of each tetrahedron.

Crystal structures and reference diffraction patterns of BaSrR4O8

2002 ◽  
Vol 17 (3) ◽  
pp. 202-209
Author(s):  
W. Wong-Ng ◽  
J. A. Kaduk ◽  
J. Dillingham
Keyword(s):  
Linear Relationship ◽  
Rietveld Refinement ◽  
Ionic Radius ◽  
Single Phase ◽  
Structure Type ◽  
Lanthanide Oxides ◽  
X Ray ◽  
Cell Parameters ◽  
Diffraction Patterns ◽  
Type Orthorhombic

The structure of BaSrR4O8 (where R=La, Nd, Sm, Gd, Eu, Dy, Ho, Y, Er, Tm, Yb, and Lu) has been investigated, and the X-ray reference patterns of these compounds have been prepared using the Rietveld refinement technique. BaSrR2O4 are isostructural to BaR2O4, which have the CaFe2O4 structure type (orthorhombic, Pnam). The cell parameters of these compounds (R=Lu to La) range from 10.125 04(10) to 10.5501(8) Å for a, 3.362 49(3) to 3.692 04(24) Å for b, 11.846 91(13) to 12.5663(9) Å for c, and 403.33 to 489.47 Å3 for V, respectively. There is a linear relationship between V and the Shannon ionic radius of R. Unlike the BaR2O4 compositions (R=Tm, Lu, and Yb), which produced a mixture of Ba3R4O9 and unreacted lanthanide oxides, single-phase BaSrTm4O8, BaSrLu4O8, and BaSrYb4O8 were successfully prepared.

Improved powder X-ray data for cancrinites IV: Franzinite

2001 ◽  
Vol 16 (4) ◽  
pp. 216-219 ◽  
Author(s):  
Paolo Ballirano ◽  
Adriana Maras
Keyword(s):  
Rietveld Refinement ◽  
X Ray Diffraction ◽  
Parallel Beam ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Figures Of Merit ◽  
Powder Diffractometer

Improved powder X-ray diffraction (XRD) data for franzinite, the ten-layer member of the cancrinite group of minerals, were obtained using an automated parallel-beam powder diffractometer with a capillary mount. The cell parameters of franzinite were found to be a=12.8976(3) Å, c=26.5040(8) Å, V=3818.2(2) Å3 in space group P321, while the strongest reflections were at 3.725(100), 3.809(65), 3.562(56), 3.586(55), 2.662(42), 2.150(31) and 3.302(30) Å. The new results include an increased number of indexed peaks, improved figures-of-merit with respect to PDF 30-1170 and intensities validated by Rietveld refinement.

Investigation of (Sr4−δCaδ)PtO6 using X-ray Rietveld refinement

1999 ◽  
Vol 14 (3) ◽  
pp. 181-189 ◽  
Author(s):  
W. Wong-Ng ◽  
J. A. Kaduk ◽  
R. A. Young ◽  
F. Jiang ◽  
L. J. Swartzendruber ◽  
...  
Keyword(s):  
Solid Solution ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Solid Solution Series ◽  
X Ray ◽  
Cell Parameters ◽  
Solution Series ◽  
Complete Solid Solution ◽  
Ca Ions ◽  
Diffraction Patterns

The structures of the solid solution series (Sr4−δCaδ)PtO6, with δ=0, 0.85(1), 2, and 3, have been investigated using the Rietveld refinement technique with laboratory X-ray powder diffraction data. A complete solid solution between Sr and Ca was confirmed to exist. These compounds crystallize in the rhombohedral space group R3¯c. The cell parameters of the series range from a of 9.4780(3) to 9.7477(1) Å, and c from 11.3301(4) to 11.8791(1) Å for δ from 3 to 0, respectively. The structure consists of chains of alternating trigonal prismatic (Sr, Ca)O6 and octahedral PtO6 units running parallel to the c axis. These chains are connected to each other via a second type of (Sr, Ca) ions, which are surrounded by eight oxygens, in a distorted square antiprismatic geometry. As Ca replaced Sr in Sr4PtO6, it was found to substitute preferentially in the smaller octahedral (Sr, Ca)1 site (6a) rather than at the eight-coordinate (Sr, Ca)2 site (18e). There appears to be an anomaly of cell parameters a and c at the compound Sr3.15Ca0.85PtO6. Their dependence on Ca content changes at δ≈1.00, where the Ca has fully replaced Sr in the 6a site. The substitution of Sr by Ca reduced the average (Sr, Ca)1–O length from 2.411 to 2.311 Å and (Sr, Ca)2–O from 2.659 to 2.570 Å as the composition varied from Sr4PtO6 to SrCa3PtO6. Reference X-ray powder diffraction patterns were prepared from the Rietveld refinement results for these members of the solid solution series. Magnetic susceptibility measurements of three of the samples (δ=0, 0.85, 2) show electronic transitions at low temperatures.

scholarly journals Crystal structure and powder X-ray diffraction data of the super-paramagnetic compound CuFeInTe3

2021 ◽  
Vol 67 (2 Mar-Apr) ◽  
pp. 305
Author(s):  
G. E. Delgado ◽  
P. Grima-Gallardo ◽  
J. A. Aitken ◽  
H. Cabrera ◽  
J. Cisterna ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Diffraction Data ◽  
Rietveld Method ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Quaternary Compound ◽  
X Ray ◽  
Cell Parameters ◽  
Figures Of Merit

The crystal structure of the new CuFeInTe3 quaternary compound was studied by the Rietveld method from powder X-ray diffraction data. The CuFeInTe3 compound crystallize in the tetragonal CuFeInSe3-type structure with space group P2c (Nº 112), and unit cell parameters a = 6.1842(1) Å, c = 12.4163(2) Å, V = 474.85(1) Å3. The density of CuFeInTe3 is rx = 5.753 g cm−3. The reliability factors of the Rietveld refinement results are Rp= 5.5%, Rwp= 6.1%, Rexp= 4.7%, and S= 1.3. The powder XRD data of CuFeInTe3 are presented and the figures of merit of indexation are M20 = 79.4 and F30 = 43.3 (0.0045, 154).

scholarly journals Rietveld Structure Refinement of the Stilbite Crystals from Deccan Traps (India) Using X-ray Powder Diffraction Data

2019 ◽  
Vol 70 (7) ◽  
pp. 2379-2384
Author(s):  
Gheorghe Branoiu ◽  
Ibrahim Ramadan
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Refinement ◽  
Deccan Traps ◽  
Western India ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Cell Parameters

The crystal structure of a spectacular sample of stilbite from Pune region located in the Deccan Traps (western India) has been refined using X-Ray powder diffraction data and the Rietveld method. The Rietveld refinement was carried out using the computer program Diffracplus TOPAS 4.1. The pseudo-Voigt (pV) profile function was used for the fit of the peaks. The Rietveld refinement of the analyzed sample in the space group C2/m (No.12): a=13.606 �, b=18.260 �, c=11.253 �, b=127.432�, Z=8, confirm the basic stilbite structure. The chemical composition of the stilbite crystals from Pune region (India) was determined by EDX analysis. The paper presents a new set of the unit cell parameters and fractional coordinates that define the stilbite crystal structure. The quality of the sample analyzed was pristine, the sample being collected from an association of apophyllite-stilbite crystals of centimetric dimensions.

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