scholarly journals Chemical Preparation, Thermal Behavior and IR Studies of the New Chromium Diphosphate Hydrate and Crystal Structure of its Corresponding Anhydrous

2021 ◽  
Vol 11 (5) ◽  
pp. 13412-13420
Keyword(s):  
Thermal Behavior ◽  
Absorption Spectrometry ◽  
Unit Cell ◽  
Ir Absorption ◽  
X Ray Diffraction ◽  
Chemical Preparation ◽  
X Ray ◽  
Ir Studies ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

Chemical preparation, thermal behavior, and IR studies are given for the diphosphate Cr4(P2O7)3.28H2O and its anhydrous form Cr4(P2O7)3. Cr4(P2O7)3.28H2O, is monoclinic P2/m with the following unit-cell dimensions : a = 16.169(1)Å, b = 9.336(5)Å, c = 9.446(4)Å, β = 124.796(5)°, and Z = 4. The total dehydration of Cr4(P2O7)3.28H2O, between 90°C and 450°C, leads to its anhydrous form, Cr4(P2O7)3. Cr4(P2O7)3 is isotopic to V4(P2O7)3, crystallizing in the orthorhombic system, space group Pmcn, Z = 4 with the following unit-cell dimensions: a = 7.25(2), b = 9.38(1)Å and c = 21.00(4)Å. Cr4(P2O7)3 is stable until its melting point at 1050°C. The thermal behavior of Cr4(P2O7)3.28H2O has been investigated and interpreted by comparison with IR absorption spectrometry and X-ray diffraction experiments.

scholarly journals The crystal structures of two polyamides (‘nylons’)

1947 ◽  
Vol 189 (1016) ◽  
pp. 39-68 ◽  
Keyword(s):  
Crystal Structures ◽  
Unit Cell ◽  
Chain Molecule ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Dimensions ◽  
C Fibre ◽  
Diffraction Patterns ◽  
Unit Cell Dimensions ◽  
Crystalline Forms

Detailed interpretations of the X -ray diffraction patterns of fibres and sheets of 66 and 6.10 polyamides (polyhexam ethylene adipamide and sebacamide respectively) are proposed. The crystal structures of the two substances are completely analogous. Fibres of these two polyam ides usually contain two different crystalline forms, α and β, which are different packings of geometrically similar molecules; most fibres consist chiefly of the α form. In the case of the 66 polymer, fibres have been obtained in which there is no detectable proportion of the β form. Unit cell dimensions and the indices of reflexions for the α form were determined by trial, using normal fibre photographs, and were checked by using doubly oriented sheets set at different angles to the X -ray beam. The unit cell of the a form is triclinic, with a — 4·9 A, b = 5·4 A, c (fibre axis) = 17·2A, α = 48 1/2º, β = 77º, γ = 63 1/2º for the 66 polymer; a = 4·95A, b = 5·4A, c (fibre axes) = 22·4A, α = 49º, β = 76 1/2º, γ = 63 1/2º for the 6.10 polymer. One chain molecule passes through the cell in both cases. Atomic coordinates in occrystals were determined by interpretation of the relative intensities of the reflexions. The chains are planar or very nearly so; the oxygen atoms appear to lie a little off the plane of the chain. The molecules are linked by hydrogen bonds between C = 0 and NH groups, to form sheets. A simple packing of these sheets of molecules gives the α arrangement.

Synthesis and crystal structure of Na3.5Cr1.5Co0.5(PO4)3 phosphate

2006 ◽  
Vol 21 (3) ◽  
pp. 210-213 ◽  
Author(s):  
Mohamed Chakir ◽  
Abdelaziz El Jazouli ◽  
Jean-Pierre Chaminade
Keyword(s):  
Crystal Structure ◽  
Three Dimensional ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
X Ray ◽  
Hexagonal Unit Cell ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

A new Nasicon phosphates series [Na3+xCr2−xCox(PO4)3(0⩽x⩽1)] was synthesized by a coprecipitation method and structurally characterized by powder X-ray diffraction. The selected compound Na3.5Cr1.5Co0.5(PO4)3 (x=0.5) crystallizes in the R3c space group with the following hexagonal unit-cell dimensions: ah=8.7285(3) Å, ch=21.580(2) Å, V=1423.8(1) Å3, and Z=6. This three-dimensional framework is built of PO4 tetrahedra and Cr∕CoO6 octahedra sharing corners. Na atoms occupy totally M(1) sites and partially M(2) sites.

The CdO–CdCl2 reaction studied by thermal analysis and X-ray diffraction: X-ray diffractogram and infrared spectrum of CdCl2•2CdO

1969 ◽  
Vol 47 (6) ◽  
pp. 1045-1050 ◽  
Author(s):  
P. Ramamurthy ◽  
E. A. Secco
Keyword(s):  
Thermal Analysis ◽  
Solid Solution ◽  
Infrared Spectrum ◽  
Band Structure ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Orthorhombic System ◽  
X Ray ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

CdO and molten CdCl2 react to form CdCl2•2CdO according to the equation:[Formula: see text]The compound CdCl2•2CdO dissociates to the oxide and chloride at 680 °C. CdO and CdCl2 form a solid solution of partial miscibility of 15% by weight of CdO.The X-ray diffractogram of CdCl2•2CdO was indexed to the orthorhombic system. The unit cell dimensions are calculated to be a = 4.38 Å, b = 11.47 Å, c = 9.93 Å with 4 molecules in the unit cell. The infrared spectrum shows a band structure of two doublets and a well-defined band in the region 370–550 cm−1.

Infrared and Raman spectra and X-ray diffraction studies of solid lead(II) carbonates

1983 ◽  
Vol 61 (3) ◽  
pp. 494-502 ◽  
Author(s):  
Murray H. Brooker ◽  
S. Sunder ◽  
Peter Taylor ◽  
Vincent J. Lopata
Keyword(s):  
Unit Cell ◽  
Spectral Features ◽  
Infrared And Raman Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Space Groups ◽  
Carbonate Ions ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Sodium And Potassium

Four basic lead carbonates were prepared and identified by X-ray powder diffractometry. These were hydrocerussite (Pb3(OH)2(CO3)2), plumbonacrite (Pb10O(OH)6(CO3)6), and the two adducts MOH•2PbCO3 (M = Na, K). New diffraction data are presented for the latter two compounds; they both have primitive hexagonal lattices with two formula units per unit cell. The unit cell dimensions of the sodium and potassium compounds are a = 5.273 ± 0.002 Å, c = 13.448 ± 0.005 Å and a = 5.348 ± 0.002 Å, c = 13.990 ± 0.005 Å, respectively. Six possible space groups are discussed.Raman and infrared spectra are reported for all four compounds, and compared with those of cerussite (PbCO3); assignment of the spectral features is discussed. Vibrational spectra of the two MOH adducts indicate that they are isostructural, and that the structure contains a well-defined lead sub-lattice, consistent with the X-ray data. The spectra of hydrocerussite and plumbonacrite indicate that lead is present as oxygen-bridged polymeric moieties in these solids. The carbonate ions occupy two and three independent sites in hydrocerussite and plumbonacrite, respectively.

X-RAY DIFFRACTION DATA FOR ALKALI DITHIONATES

1963 ◽  
Vol 41 (2) ◽  
pp. 219-223 ◽  
Author(s):  
D. W. Larson ◽  
A. B. VanCleave
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Dimensions ◽  
Diffraction Patterns ◽  
Unit Cell Dimensions

X-Ray powder diffraction patterns have been recorded for the alkali dithionates and for barium and ammonium dithionate. The patterns have been indexed and unit cell dimensions determined for lithium dithionate dihydrate, sodium dithionate (anhydrous), and rubidium dithionate. Previously determined cell dimensions have been confirmed in other cases.

Site-occupancy scheme in disordered Ca3RE2(BO3)4: a dependence on rare-earth (RE) ionic radius

2021 ◽  
Vol 77 (3) ◽  
Author(s):  
Katarzyna M. Kosyl ◽  
Wojciech Paszkowicz ◽  
Roman Minikayev ◽  
Alexey N. Shekhovtsov ◽  
Miron B. Kosmyna ◽  
...  
Keyword(s):  
Rare Earth ◽  
Ionic Radius ◽  
Site Occupancy ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Interatomic Distances ◽  
X Ray ◽  
Cell Parameters ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

The structures of polycrystalline Ca3RE2(BO3)4 (RE = La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Y; space group Pnma) orthoborates were determined using powder X-ray diffraction. Trends in the unit-cell dimensions and yet unreported trends in other structural properties (interatomic distances and the fractional occupation of three Ca/RE sites) for these compounds are demonstrated as a function of RE ionic radius. The unit-cell volume and a unit-cell parameter present a linear dependence, while the b and c unit-cell parameters change in a nonlinear manner. For the whole series, the RE atoms are present at all three cationic sites (labelled as M1, M2 and M3), but the fractional occupancies depend on the RE ionic radius. The small rare-earth atoms tend to enter mainly the M3 site; for the larger rare earths, the occupancy of this site decreases sharply. The occupancy of the M1 site by RE atoms is around 0.5 and tends to increase with increasing RE ionic radius. The M2 site is the least preferentially occupied by RE ions, but the occupancy discernibly increases with rising radius as well. These findings are assembled with properties of isostructural strontium and barium borates, allowing prediction of occupancy schemes for not yet investigated compounds from the A 3RE2(BO3)4 (A = Ca, Ba, Sr).

Changes in the Unit Cell Dimensions of ZSM-5 Produced by the Adsorption of Organic Liquids*

1985 ◽  
Vol 29 ◽  
pp. 257-264
Author(s):  
S. S. Pollack ◽  
R.J. Gormley ◽  
E. L. Wetzel
Keyword(s):  
Diffraction Pattern ◽  
Organic Solvents ◽  
Unit Cell ◽  
Organic Liquids ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Dimensions ◽  
Diffraction Patterns ◽  
Considerable Work ◽  
Unit Cell Dimensions

The adsorption of liquids in 2eolites has been a widely studied phenomenon, and with the development of ZSM-5, considerable work has been carried out on this zeolite, However, few articles have been published dealing with changes in the X-ray diffraction patterns when the zeolite pores contain adsorbed molecules. The purpose of this paper is to report changes in the X-ray diffraction pattern of ZSM-5 after mixing it with various organic solvents.This work began after studies of both deactivated and partially deactivated ZSM-5 catalysts showed that their X-ray diffraction patterns changed in intensities and peak positions after use in microreactor studies. If coke or hydrocarbons were causing the above changes, as postulated, would hydrocarbons adsorbed in ZSM-5 produce the same changes? Simpson and Steinfink showed that the low-angle lines of faujasite decreased in intensity after the adsorption of m-dichlorobenzene.

Crystallization and preliminary X-ray diffraction studies of E. coli porphobilinogen synthase and its heavy-atom derivatives

1998 ◽  
Vol 54 (3) ◽  
pp. 438-440 ◽  
Author(s):  
L. Shimoni-Livny ◽  
H. L. Carrell ◽  
T. Wagner ◽  
A. Kaufman Katz ◽  
C. Afshar ◽  
...  
Keyword(s):  
Active Sites ◽  
Aminolevulinic Acid ◽  
Heavy Atom ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
E Coli ◽  
Cell Dimensions ◽  
Porphobilinogen Synthase ◽  
Unit Cell Dimensions

Porphobilinogen synthase (PBGS) catalyzes the condensation of two identical substrate molecules, 5-aminolevulinic acid (ALA), in an asymmetric manner to form porphobilinogen. E. coli PBGS is an homooctameric enzyme. The number of active sites is not clear, but each subunit binds one ZnII ion and one MgII ion. Diffraction-quality crystals of native E. coli PBGS have been obtained, and unit-cell dimensions (a = 130.8, c = 144.0 Å) are reported. These crystals diffract to about 3.0 Å resolution.

scholarly journals Matching X-ray source, optics and detectors to protein crystallography requirements

1999 ◽  
Vol 55 (10) ◽  
pp. 1663-1668 ◽  
Author(s):  
Colin Nave
Keyword(s):  
Radiation Damage ◽  
Diffraction Pattern ◽  
Spatial Resolution ◽  
Diffraction Data ◽  
Incident Beam ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

A review of the requirements for collecting X-ray diffraction data from protein crystals is given, with an emphasis on the properties of the crystal and its diffraction pattern. The size, unit-cell dimensions and perfection of the crystals can all be related to the required size and divergence of the incident X-ray beam, together with the size and spatial resolution of the detector. The X-ray beam causes primary radiation damage, even in frozen crystals. If the incident beam is very intense, temperature rises and gradients could occur in the crystal. The extent to which these problems can be overcome is also discussed.

scholarly journals Exploring cycling induced crystallographic change in NMC with X-ray diffraction computed tomography

2020 ◽  
Vol 22 (32) ◽  
pp. 17814-17823 ◽  
Author(s):  
Sohrab R. Daemi ◽  
Chun Tan ◽  
Antonis Vamvakeros ◽  
Thomas M. M. Heenan ◽  
Donal P. Finegan ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Dimensions ◽  
Electrochemical Cycling ◽  
Unit Cell Dimensions

This study presents the application of XRD-CT combined with FIB-SEM to analyze the crystal dimensions of LiNi0.33Mn0.33Co0.33O2 electrodes and spatially localise the change in unit cell dimensions as a result of electrochemical cycling.

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