scholarly journals Single-Crystal 31P and 7Li NMR of the Ionic Conductor LiH2PO4

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 302
Author(s):  
Otto E. O. Zeman ◽  
Viktoria Kainz ◽  
Thomas Bräuniger
Keyword(s):  
Single Crystal ◽  
Rotation Axis ◽  
Polycrystalline Sample ◽  
Magic Angle Spinning ◽  
Ionic Conductor ◽  
Dihydrogen Phosphate ◽  
Magic Angle ◽  
Orthorhombic Crystal ◽  
Quadrupolar Coupling ◽  
Angle Spinning

The electronic surroundings of phosphorus and lithium atoms in the ionic conductor lithium dihydrogen phosphate (LDP) have been studied by single-crystal nuclear magnetic resonance (NMR) spectroscopy at room temperature. From orientation-dependent NMR spectra of a large homegrown LDP single crystal, the full 31P chemical shift (CS) and 7Li quadrupole coupling (QC) tensor was determined, using a global fit over three rotation patterns. The resulting CS tensor is characterized by its three eigenvalues: δ 11 P A S = ( 67.0 ± 0.6 ) ppm, δ 22 P A S = ( 13.9 ± 1.5 ) ppm, and δ 33 P A S = ( − 78.7 ± 0.9 ) ppm. All eigenvalues have also been verified by magic-angle spinning NMR on a polycrystalline sample, using Herzfeld–Berger analysis of the rotational side band pattern. The resulting 7Li QC tensor is characterized by its quadrupolar coupling constant χ = Q 33 P A S = ( − 71 ± 1 ) kHz and the two eigenvalues Q 11 P A S = ( 22.3 ± 0.9 ) kHz, and Q 22 P A S = ( 48.4 ± 0.8 ) kHz. The initially unknown orientation of the mounted crystal, expressed by the orientation of the rotation axis in the orthorhombic crystal frame, was included in the global data fit as well, thus obtaining it from NMR data only.

scholarly journals Determination of the Full 207Pb Chemical Shift Tensor of Anglesite, PbSO4, and Correlation of the Isotropic Shift to Lead–Oxygen Distance in Natural Minerals

Crystals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 43 ◽  
Author(s):  
Otto Zeman ◽  
Jennifer Steinadler ◽  
Rupert Hochleitner ◽  
Thomas Bräuniger
Keyword(s):  
Chemical Shift ◽  
Single Crystal ◽  
Polycrystalline Sample ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Isotropic Chemical Shift ◽  
Natural Minerals ◽  
Angle Spinning ◽  
Data Acquisition And Processing

The full 207 Pb chemical shift (CS) tensor of lead in the mineral anglesite, PbSO 4 , was determined from orientation-dependent nuclear magnetic resonance (NMR) spectra of a large natural single crystal, using a global fit over two rotation patterns. The resulting tensor is characterised by the reduced anisotropy Δ δ = ( - 327 ± 4 ) ppm, asymmetry η C S = 0 . 529 ± 0 . 002 , and δ i s o = ( - 3615 ± 3 ) ppm, with the isotropic chemical shift δ i s o also verified by magic-angle spinning NMR on a polycrystalline sample. The initially unknown orientation of the mounted single crystal was included in the global data fit as well, thus obtaining it from NMR data only. By use of internal crystal symmetries, the amount of data acquisition and processing for determination of the CS tensor and crystal orientation was reduced. Furthermore, a linear correlation between the 207 Pb isotropic chemical shift and the shortest Pb–O distance in the co-ordination sphere of Pb 2 + solely surrounded by oxygen has been established for a large database of lead-bearing natural minerals.

Elucidation of correlated disorder in zeolite IM-18

2019 ◽  
Vol 75 (3) ◽  
pp. 333-342 ◽  
Author(s):  
Xiaoge Wang ◽  
Yihan Shen ◽  
Rongli Liu ◽  
Xiaolong Liu ◽  
Cong Lin ◽  
...  
Keyword(s):  
Single Crystal ◽  
Polycrystalline Sample ◽  
Simulation Method ◽  
Magic Angle Spinning ◽  
Two Dimensions ◽  
Mas Nmr ◽  
Double Quantum ◽  
Magic Angle ◽  
Disordered Structures ◽  
Angle Spinning

Classical crystallography is based on the translational periodicity of crystals and the analysis of discrete Bragg reflections. However, it is inadequate for determining disordered structures, of which the diffuse scattering is vital to evaluate the disorder level. The correlated disorder of IM-18 presents as zigzag chains arranged in translational periodicity and the double four-ring units randomly distributed along two dimensions. Supercell models regulated by multiple probabilities were systematically built to simulate the single-crystal and powder X-ray diffraction patterns in order to ascertain the specific disorder configuration in the single-crystal or polycrystalline samples of IM-18. The presence of defects in the polycrystalline sample was proved by combining 29Si magic angle spinning (MAS) NMR and 1H–1H double quantum MAS NMR spectra, and was quantitatively explored by the simulation method. The method could also elucidate other disordered structures in polycrystalline or single-crystal samples, despite the presence of defects or multidimensional disorder.

THE LOCAL STRUCTURE OF BISMUTH-BORATES CHARACTERIZED BY 11B MAS NMR

2002 ◽  
Vol 16 (12) ◽  
pp. 423-431 ◽  
Author(s):  
M. VASILESCU ◽  
S. SIMON
Keyword(s):  
Heat Treatment ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Magic Angle ◽  
Borate Glasses ◽  
Bismuth Borate ◽  
Mean Values ◽  
Quadrupolar Coupling ◽  
Angle Spinning ◽  
Bismuth Borates

Bismuth-borate glasses and vitroceramics belonging to x Bi 2 O 3 · (100 - x) B 2 O 3 system, 0 ≤ x ≤ 93, doped with 0.5 mol% MnO are investigated by 11 B Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR). The 11 B MAS NMR results indicate the presence of three- and tetra-coordinated boron in all investigated bismuth borates. While the fraction of the tetra-coordinated boron present a large maximum in the range 20 ≤ x ≤ 60 in the bismuth-borate glasses, this maximum is reduced to the range 20 ≤ x ≤ 37.5 in the samples obtained after heat treatment. Crystalline phases are developed in the samples with high bismuth content, x ≥ 60, by heat treatment at 550°C, in which two types of three-coordinated boron are identified. The mean values of the NMR parameters like chemical shift, asymmetry parameter and quadrupolar coupling constant are less influenced by the bismuth/boron ratio, showing that boron structural units are relatively stable on the entire investigated composition range.

scholarly journals 14N, 13C, and 119Sn solid-state NMR characterization of tin(II) carbodiimide Sn(NCN)

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Aleksander Jaworski ◽  
Jędrzej Piątek ◽  
Liuda Mereacre ◽  
Cordula Braun ◽  
Adam Slabon
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Chemical Shifts ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Quadrupolar Coupling ◽  
Nmr Study ◽  
Nmr Characterization ◽  
Angle Spinning ◽  
High Level

Abstract We report the first magic-angle spinning (MAS) nuclear magnetic resonance (NMR) study on Sn(NCN). In this compound the spatially elongated (NCN)2− ion is assumed to develop two distinct forms: either cyanamide (N≡C–N2−) or carbodiimide (−N=C=N−). Our 14N MAS NMR results reveal that in Sn(NCN) the (NCN)2− groups exist exclusively in the form of symmetric carbodiimide ions with two equivalent nitrogen sites, which is in agreement with the X-ray diffraction data. The 14N quadrupolar coupling constant | C Q | $\vert {C}_{\text{Q}}\vert $  ≈ 1.1 MHz for the −N=C=N− ion in Sn(NCN) is low when compared to those observed in molecular compounds that comprise cyano-type N≡C– moieties ( | C Q | $\vert {C}_{\text{Q}}\vert $  > 3.5 MHz). This together with the information from 14N and 13C chemical shifts indicates that solid-state NMR is a powerful tool for providing atomic-level insights into anion species present in these compounds. The experimental NMR results are corroborated by high-level calculations with quantum chemistry methods.

scholarly journals SYSU-6, A New 2-D Aluminophosphate Zeolite Layer Precursor

Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 2972 ◽  
Author(s):  
Jiang-Zhen Qiu ◽  
Long-Fei Wang ◽  
Jiuxing Jiang
Keyword(s):  
Electron Microscopy ◽  
Single Crystal ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
Structure Directing Agent ◽  
X Ray ◽  
Uv Raman ◽  
Angle Spinning ◽  
Inorganic Framework

Two-dimensional aluminophosphate is an important precursor of phosphate-based zeolites; a new Sun Yat-sen University No. 6 (SYSU-6) with |Hada|2[Al2(HPO4)(PO4)2] has been synthesized in the hydrothermal synthesis with organic structure-directing agent (OSDA) of N,N,3,5-tetramethyladamantan-1-amine. In this paper, SYSU-6 is characterized by single-crystal/powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, transmission electron microscopy, infrared and UV Raman spectroscopy, solid-state 27Al, 31P and 13C magic angle spinning (MAS) NMR spectra, and elemental analysis. The single-crystal X-ray diffraction structure indicates that SYSU-6 crystallized in the space group P21/n, with a = 8.4119(3), b = 36.9876(12), c = 12.5674(3), α = 90°, β = 108.6770(10)°, γ = 90°, V = 3704.3(2) Å3, Z = 4, R = 5.12%, for 8515 observed data (I > 2σ(I)). The structure has a new 4,12-ring layer framework topology linked by alternating AlO4 and PO4 tetrahedra. The organic molecules reside between the layers and are hydrogen-bonded to the inorganic framework. The new type of layer provides a greater opportunity to construct zeolite with novel topology.

scholarly journals A Practical Review of NMR Lineshapes for Spin-1/2 and Quadrupolar Nuclei in Disordered Materials

2020 ◽  
Vol 21 (16) ◽  
pp. 5666 ◽  
Author(s):  
Kuizhi Chen
Keyword(s):  
Chemical Shift ◽  
Structural Disorder ◽  
Magic Angle Spinning ◽  
Second Order ◽  
Double Quantum ◽  
Magic Angle ◽  
Quadrupolar Nuclei ◽  
Isotropic Chemical Shift ◽  
Quadrupolar Coupling ◽  
Angle Spinning

NMR is a powerful spectroscopic method that can provide information on the structural disorder in solids, complementing scattering and diffraction techniques. The structural disorder in solids can generate a dispersion of local magnetic and electric fields, resulting in a distribution of isotropic chemical shift δiso and quadrupolar coupling CQ. For spin-1/2 nuclei, the NMR linewidth and shape under high-resolution magic-angle spinning (MAS) reflects the distributions of isotropic chemical shift, providing a rich source of disorder information. For quadrupolar nuclei, the second-order quadrupolar broadening remains present even under MAS. In addition to isotropic chemical shift, structural disorder can impact the electric field gradient (EFG) and consequently the quadrupolar NMR parameters. The distributions of quadrupolar coupling and isotropic chemical shift are superimposed with the second-order quadrupolar broadening, but can be potentially characterized by MQMAS (multiple-quantum magic-angle spinning) spectroscopy. We review analyses of NMR lineshapes in 2D DQ–SQ (double-quantum single-quantum) and MQMAS spectroscopies, to provide a guide for more general lineshape analysis. In addition, methods to enhance the spectral resolution and sensitivity for quadrupolar nuclei are discussed, including NMR pulse techniques and the application of high magnetic fields. The role of magnetic field strength and its impact on the strategy of determining optimum NMR methods for disorder characterization are also discussed.

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