Effect of the cation mobility on the X-ray diffraction pattern and the Si MAS NMR spectra of Na,CoY zeolites

1998 ◽  
Vol 21 (1-3) ◽  
pp. 19-25 ◽  
Author(s):  
M Solache ◽  
I Garcı́a ◽  
P Bosch ◽  
S Bulbulian ◽  
A Blumenfeld ◽  
...  
Keyword(s):  
Diffraction Pattern ◽  
Nmr Spectra ◽  
Mas Nmr ◽  
X Ray Diffraction ◽  
Cation Mobility ◽  
X Ray

Characterization of aluminosilicate (mullite) precursors prepared by a mechanochemical process

1998 ◽  
Vol 13 (8) ◽  
pp. 2184-2189 ◽  
Author(s):  
J. Temuujin ◽  
K. Okada ◽  
K. J. D. MacKenzie
Keyword(s):  
Heat Treatment ◽  
Nmr Spectra ◽  
Spinel Phase ◽  
Mas Nmr ◽  
X Ray Diffraction ◽  
Hydrated Alumina ◽  
X Ray ◽  
New Si ◽  
Grinding Time

Aluminosilicate precursors were prepared by mechanochemical treatment of gibbsitesilica gel mixtures. The effect of grinding on their structure and thermal behavior has been examined by 27Al and 29Si MAS NMR, x-ray diffraction (XRD), differential thermal analysis-thermogravimetry (DTA-TG), and Fourier transform infrared (FTIR). After 8 h grinding, the hydrated alumina was completely changed to an amorphous phase which showed a new exothermic DTA peak at about 980 °C due to the formation of γ–Al2O3 or spinel phase. This behavior was related to changes in the Al and Si environments, as deduced from the MAS NMR spectra. With increased grinding time, some 4-coordinated Al appears, together with an Al resonance at about 30 ppm. Simultaneously, a new Si resonance appears at about −90 ppm, indicating a greater degree of homogeneity in the ground samples. Mullite crystallizes at 1200 °C from samples ground for 8–20 h, its XRD intensity increasing with increased milling times, in agreement with the NMR, DTA, and FTIR data. Changes in the Al and Si environments during heat treatment, as reflected by the NMR spectra, are also reported.

Structural organization of mercury(II) and copper(II) dithiocarbamates from EPR and 13C and 15N MAS NMR spectra and X-ray diffraction analysis

2008 ◽  
Vol 34 (1) ◽  
pp. 59-69 ◽  
Author(s):  
A. V. Ivanov ◽  
E. V. Korneeva ◽  
B. V. Bukvetskii ◽  
A. S. Goryan ◽  
O. N. Antzutkin ◽  
...  
Keyword(s):  
Diffraction Analysis ◽  
Nmr Spectra ◽  
Structural Organization ◽  
Mas Nmr ◽  
X Ray Diffraction ◽  
X Ray

Application of MAS NMR spectroscopy to poorly crystalline minerals: viséite

1996 ◽  
Vol 60 (403) ◽  
pp. 957-962 ◽  
Author(s):  
Yeongkyoo Kim ◽  
R. James Kirkpatrick
Keyword(s):  
Nmr Spectroscopy ◽  
Diffraction Pattern ◽  
Single Phase ◽  
Mas Nmr ◽  
Powder Xrd ◽  
X Ray Diffraction ◽  
X Ray ◽  
Si Content

AbstractViséite is a poorly crystalline mineral which is difficult to study by X-ray diffraction pattern. NMR is a very useful technique to study such poorly crystalline minerals, and 31P, 27Al, and 29Si MAS NMR in conjunction with powder XRD results show that at least our Viséite sample is not a single phase with a structure analogous to that of analcime as previously reported. Rather, it is very disordered with a structure similar to that of crandallite and includes other phases including an undefined aluminophosphate, opal, and a framework aluminosilicate, probably a zeolite. The previously reported variations in the Si content of Viséite are probably due to variable amounts of opal and the framework aluminosilicate.

6Li and 7Li MAS NMR and In Situ X-ray Diffraction Studies of Lithium Manganate Cathode Materials

1998 ◽  
Vol 548 ◽  
Author(s):  
Young Joo Lee ◽  
Francis Wang ◽  
Clare P. Grey ◽  
Sanjeev Mukerjee ◽  
James McBreen
Keyword(s):  
Cathode Materials ◽  
Nmr Spectra ◽  
Manganese Oxides ◽  
Mas Nmr ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Lithium Manganese Oxides ◽  
Diffraction Patterns

ABSTRACT6Li MAS NMR spectra of lithium manganese oxides with differing manganese oxidation states (LiMn2O4, Li4Mn5O12, Li2Mn4O9, and Li2Mn2O4) are presented. Improved understanding of the lithium NMR spectra of these model compounds is used to interpret the local structure of the LixMn2O4 cathode materials following electrochemical Li+ deintercalation to various charging levels. In situ x-ray diffraction patterns of the same material during charging are also reported for comparison. Evidence for two-phase behavior for x < 0.4 (LixMn2O4) is seen by both NMR and diffraction.

Na3GaF6 – A crystal chemical and solid state NMR spectroscopic study

2018 ◽  
Vol 233 (7) ◽  
pp. 479-487 ◽  
Author(s):  
David Böhnisch ◽  
Stefan Seidel ◽  
Christopher Benndorf ◽  
Thomas Jansen ◽  
Lena Funke ◽  
...  
Keyword(s):  
Solid State Nmr ◽  
Nmr Spectra ◽  
Chemical Exchange ◽  
Center Of Mass ◽  
Mas Nmr ◽  
X Ray Diffraction ◽  
X Ray ◽  
Exchange Effects ◽  
Distorted Octahedral ◽  
Motional Narrowing

Abstract Na3GaF6 and Na3GaF6:Mn4+ samples were obtained from NaNO3 and Ga(NO3)3·9H2O in hydrofluoric acid using K2MnF6 or NaMnO4 as manganese sources. The structure of Na3GaF6 was studied by single crystal X-ray diffraction at 90, 293, 440 and 500 K, confirming the monoclinic cryolite type structure, space group P21/c. The gallium atoms show slightly distorted octahedral coordination by fluorine atoms, similar to the Na1 atoms. Coordination number 8 is observed for Na2. Both sodium sites are clearly distinguished by 23Na MAS-NMR spectroscopy. Above 400 K the spectra reveal distinct chemical exchange effects, signifying sodium ion hopping between these two sites. At the same time static 19F NMR spectra indicate pronounced motional narrowing effects in this temperature region. The nearly invariant 69Ga MAS-NMR spectra suggest that any reorientational motion involving the GaF63− ions (if present) occurs with preservation of the center of mass of these octahedra.

Investigation of Phosphorus Site Condensation in CaHPO4 by Analysis of 31P MAS-NMR Tensor and X-Ray Powder Patterns

2006 ◽  
Vol 61 (7-8) ◽  
pp. 375-382 ◽  
Author(s):  
Faouzi Hlel ◽  
Saber Kamoun ◽  
Kamel Guidara
Keyword(s):  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Room Temperature ◽  
Chemical Shifts ◽  
Mas Nmr ◽  
Slow Evaporation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Annealing Temperatures ◽  
31P Mas Nmr

CaHPO4 was obtained by slow evaporation at room temperature. Seven samples, obtained at different annealing temperatures, were characterized by X-ray diffraction and 31P MAS-NMR spectroscopy. All NMR spectra were analyzed using a DMFIT program. At room temperature, the observed 31P NMR chemical shifts for the title compound were −1.59, −0.36 and 1.26 ppm with the relative intensities 39%, 10% and 51%, revealing the presence of three non-equivalent phosphorus sites in the structure. The investigation of the NMR tensor shift of all spectra shows that the abounding HPO2−4 anion was progressively transformed into P2O4−7 when the temperature increased

Electron Microscopy of Shock Loaded Polycrystalline Beryllium

1974 ◽  
Vol 32 ◽  
pp. 506-507 ◽  
Author(s):  
J. M. Galbraith ◽  
L. E. Murr ◽  
A. L. Stevens
Keyword(s):  
Electron Microscopy ◽  
Wave Propagation ◽  
Structural Change ◽  
Single Crystal ◽  
Diffraction Pattern ◽  
Shock Loading ◽  
Slip Systems ◽  
Compression Tests ◽  
X Ray Diffraction ◽  
X Ray

Uniaxial compression tests and hydrostatic tests at pressures up to 27 kbars have been performed to determine operating slip systems in single crystal and polycrystal1ine beryllium. A recent study has been made of wave propagation in single crystal beryllium by shock loading to selectively activate various slip systems, and this has been followed by a study of wave propagation and spallation in textured, polycrystal1ine beryllium. An alteration in the X-ray diffraction pattern has been noted after shock loading, but this alteration has not yet been correlated with any structural change occurring during shock loading of polycrystal1ine beryllium.This study is being conducted in an effort to characterize the effects of shock loading on textured, polycrystal1ine beryllium. Samples were fabricated from a billet of Kawecki-Berylco hot pressed HP-10 beryllium.

Cytomembrane Preservation in Tissue Dehydrated Only With Glutaraldehyde and Epon 812 Resin

1973 ◽  
Vol 31 ◽  
pp. 320-321
Author(s):  
Daniel C. Pease
Keyword(s):  
Diffraction Pattern ◽  
X Ray Diffraction ◽  
High Concentration ◽  
Unpublished Study ◽  
X Ray ◽  
Sectioned Material

A previous study demonstrated that tissue could be successfully infiltrated with 50% glutaraldehyde, and then subsequently polymerized with urea to create an embedment which retained cytomembrane lipids in sectioned material. As a result, the 180-190 Å periodicity characteristic of fresh, mammalian myelin was preserved in sections, as was a brilliant birefringence, and the capacity to bind OsO4 vapor in the hydrophobic bilayers. An associated (unpublished) study, carried out in co-operation with Drs. C.K. Akers and D.F. Parsons, demonstrated that the high concentration of glutaraldehyde (and urea) did not significantly alter the X-ray diffraction pattern of aldehyde-fixed, myelin. Thus, by itself, 50% glutaraldehyde has little effect upon cytomembrane systems and can be used with confidence for the first stages of dehydration.

The Electron Effect of Aromatic Group: Control Conformation of 2-Aromatic Cyclododecanone Derivatives

2020 ◽  
Vol 24 (10) ◽  
pp. 1139-1147
Author(s):  
Yang Mingyan ◽  
Wang Daoquan ◽  
Wang Mingan
Keyword(s):  
1H Nmr ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
The Other ◽  
Repulsive Interaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Effect ◽  
Group Control

2-Phenylcyclododecanone and 2-cyclohexylcyclododecanone derivatives were synthesized and characterized by 1H NMR, 13C NMR, HR-ESI-MS and X-ray diffraction. Their preferred conformations were analyzed by the coupling constants in the 1H NMR spectra and X-ray diffraction, which showed the skeleton ring of these derivatives containing [3333]-2-one conformation, and the phenyl groups were located at the side-exo position of [3333]-2-one conformation due to the strong π-π repulsive interaction between the π- electron of benzene ring and π-electron of carbonyl group. The cyclohexyl groups were located at the corner-syn or the side-exo position of [3333]-2-one conformation depending on the hindrance of the other substituted groups. The π-π electron effect played a crucial role in efficiently controlling the preferred conformation of 2-aromatic cyclododecanone and the other 2-aromatic macrocyclic derivatives with the similar preferred square and rectangular conformations.

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