scholarly journals The Evaluation of Clay Suitability for Geopolymer Technology

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 852
Author(s):  
Tomáš Hanzlíček ◽  
Ivana Perná ◽  
Kateřina Uličná ◽  
Václav Římal ◽  
Helena Štěpánková
Keyword(s):  
Thermal Treatment ◽  
Evaluation Method ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Magic Angle ◽  
Clay Material ◽  
X Ray Diffraction ◽  
Alternative Evaluation ◽  
Angle Spinning ◽  
Kaolinitic Clay

In the last 20 years, laboratory work on geopolymer technology has been confronted with the necessity to determine whether a certain clay material has the properties necessary to form genuine geopolymer when thermally treated and alkalized. The assessment of the properties of clay source materials and of the ability of the materials to form geopolymer 3D netting mainly involves the study of the aluminum transformation level during the thermal treatment of the clay. The presented study combines several classical analytical methods (chemical and mineralogical analyses, the calculation of the Hinckley index (HI) based on X-ray diffraction analyses, and the measurement of particle size distribution) for eleven samples of kaolin and kaolinitic clay of various origins and coming from different locations. The results of these methods have been compared with those of 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) in solid state. Based on them, the mentioned methods could be combined for an estimation of the aluminum-ion behavior during the thermal treatment of the clay. HI calculations have shown favorable agreement in 63% of the kaolin samples studied, especially for high purity kaolin without significant impurities in the form of feldspars and/or quartz. The main aim of this work is not to replace the precise MAS–NMR analysis, but to offer an alternative evaluation method when MAS–NMR is not available.

Mixed Carbides via Polymer Route

1990 ◽  
Vol 180 ◽  
Author(s):  
Gian D. Soraru ◽  
Florence Babonneau ◽  
John D. Mackenzie
Keyword(s):  
Magic Angle Spinning ◽  
Transformation Process ◽  
Mas Nmr ◽  
Magic Angle ◽  
Pyrolysis Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Metallic Element ◽  
Angle Spinning

ABSTRACTSeveral polymetallocarbosilanes, pre-ceramics precursors for Si-M-C-O systems, have been prepared from polycarbosilane and metallic alkoxides, M(OR)n with M = Ti, Zr and Al. Polymers have essentially been characterized by Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR). The pyrolysis process has been followed for each system with X-Ray Diffraction (XRD) and MAS-NMR. The role of the metallic element M on the transformation process of these systems will be discussed.

Low temperature synthesis of MgAl2O4 Spinel through sol-gel technique and its characterization

2015 ◽  
Vol 93 (5) ◽  
pp. 561-564 ◽  
Author(s):  
G. Neeraja Rani ◽  
N.H. Ayachit
Keyword(s):  
Spinel Phase ◽  
Sol Gel ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
Thermal Analyzer ◽  
Gel Technique ◽  
Lower Temperature ◽  
Angle Spinning

MgAl2O4 spinel was synthesized by a novel route method of sol-gel technique. Spinel powders were sintered at various temperatures to investigate the phase contents and crystallinity. The characterization of the samples was carried out by using various techniques. The formation of the spinel phase was inferred by differential thermal analyzer, while crystalline and structural properties were studied by X-ray diffraction, Fourier transform infrared spectroscopy and magic angle spinning nuclear magnetic resonance (MAS-NMR). These studies infer the formation of spinel phase at much lower temperature (around 375 °C) and order–disorder transition in the spinel around 700 °C. The studies also indicate the formation of the spinel with better crystallinity. The inversion parameter was also calculated using MAS-NMR and its value is found to be approximately 0.30 for a sample sintered around 1000 °C.

MAS NMR investigation of kaolinite-smectite structure using 6Li and 29Si with Mn exchange

Clay Minerals ◽  
2007 ◽  
Vol 42 (2) ◽  
pp. 181-186 ◽  
Author(s):  
J. Cuadros ◽  
T. Wing-Dudek
Keyword(s):  
Complex Structure ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Magic Angle ◽  
Signal Loss ◽  
X Ray Diffraction ◽  
Two Samples ◽  
Before And After ◽  
Angle Spinning ◽  
Mixed Layers

AbstractKaolinite-smectite mixed-layers have been found to have a complex structure with smectite and kaolinite domains within layers. Here we further investigate this structure in samples with 0–80% kaolinite layers, as determined by X-ray diffraction, by means of magic angle spinning nuclear magnetic resonance (MAS NMR) of 29Si and 6Li. The 29Si NMR experiments were carried out on two samples (55 and 80% kaolinite layers), before and after their exchange with Mn2+, a paramagnetic ion that causes NMR signal loss from neighbouring nuclei, in order to investigate the distance between Mn ions and Si atoms in kaolinite sites. The 29Si NMR intensity from such sites (at ~–91 ppm) was reduced upon Mn exchange, indicating that some Mn ions are located near kaolinite Si sites. The position of the 6Li peak changes slightly (–1.3 to –1.8 ppm) but progressively with increasing kaolinite content (0–80% kaolinite layers) of four K-S specimens, suggesting two slightly different chemical environments for interlayer Li, one related to smectite and the other to kaolinite. The two sets of experiments are consistent with a complex structure of kaolinite-smectite, including smectite and kaolinite domains within layers and/or interlayers of varying smectitic and kaolinitic character.

scholarly journals Combination of solid state NMR and DFT calculation to elucidate the state of sodium in hard carbon electrodes

2016 ◽  
Vol 4 (34) ◽  
pp. 13183-13193 ◽  
Author(s):  
Ryohei Morita ◽  
Kazuma Gotoh ◽  
Mika Fukunishi ◽  
Kei Kubota ◽  
Shinichi Komaba ◽  
...  
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Dft Calculation ◽  
Magic Angle Spinning ◽  
The State ◽  
Mas Nmr ◽  
Magic Angle ◽  
Multiple Quantum ◽  
Hard Carbon ◽  
Angle Spinning

We examined the state of sodium electrochemically inserted in HC prepared at 700–2000 °C using solid state Na magic angle spinning (MAS) NMR and multiple quantum (MQ) MAS NMR.

scholarly journals Sampling Method Affects HR-MAS NMR Spectra of Healthy Caprine Brain Biopsies

Metabolites ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 38
Author(s):  
Annakatrin Häni ◽  
Gaëlle Diserens ◽  
Anna Oevermann ◽  
Peter Vermathen ◽  
Christina Precht
Keyword(s):  
Nmr Spectroscopy ◽  
Sampling Method ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Magic Angle ◽  
1H Nuclear Magnetic Resonance ◽  
Rapid Changes ◽  
Tissue Degradation ◽  
Angle Spinning

The metabolic profiling of tissue biopsies using high-resolution–magic angle spinning (HR-MAS) 1H nuclear magnetic resonance (NMR) spectroscopy may be influenced by experimental factors such as the sampling method. Therefore, we compared the effects of two different sampling methods on the metabolome of brain tissue obtained from the brainstem and thalamus of healthy goats by 1H HR-MAS NMR spectroscopy—in vivo-harvested biopsy by a minimally invasive stereotactic approach compared with postmortem-harvested sample by dissection with a scalpel. Lactate and creatine were elevated, and choline-containing compounds were altered in the postmortem compared to the in vivo-harvested samples, demonstrating rapid changes most likely due to sample ischemia. In addition, in the brainstem samples acetate and inositols, and in the thalamus samples ƴ-aminobutyric acid, were relatively increased postmortem, demonstrating regional differences in tissue degradation. In conclusion, in vivo-harvested brain biopsies show different metabolic alterations compared to postmortem-harvested samples, reflecting less tissue degradation. Sampling method and brain region should be taken into account in the analysis of metabolic profiles. To be as close as possible to the actual situation in the living individual, it is desirable to use brain samples obtained by stereotactic biopsy whenever possible.

Article

1999 ◽  
Vol 77 (11) ◽  
pp. 1962-1972
Author(s):  
Scott Kroeker ◽  
Roderick E Wasylishen
Keyword(s):  
Nmr Spectra ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Spin Coupling ◽  
Group Symmetry ◽  
Magic Angle ◽  
Chemical Shielding ◽  
Shielding Tensor ◽  
Angle Spinning ◽  
Spin Spin Coupling

Direct NMR observation of copper-63/65 nuclei in solid K3Cu(CN)4 provides the first experimental example of anisotropic copper chemical shielding. Axially symmetric by virtue of the space group symmetry, the shielding tensor spans 42 ppm, with the greatest shielding when the unique axis is perpendicular to the applied magnetic field. The nuclear quadrupole coupling constant is also appreciable, CQ(63Cu) = -1.125 MHz, reflecting a deviation of the Cu(CN)43- anion from pure tetrahedral symmetry. Spin-spin coupling to 13C nuclei in an isotopically enriched sample is quantified by line-shape simulations of both 13C and 63/65Cu magic-angle spinning (MAS) NMR spectra to be 300 Hz. It is shown that this information is also directly available by 63/65Cu triple-quantum (3Q) MAS NMR. The relative merits of these three approaches to characterizing spin-spin couplings involving half-integer quadrupolar nuclei are discussed. Chemical shielding tensors for nitrogen-15 and carbon-13 are obtained from NMR spectra of non-spinning samples, and are compared to those of tetrahedral group 12 tetracyanometallates. Finally, 2J(63/65Cu,15N) detected in 15N MAS experiments are found to be 19 and 20 Hz for the two crystallographically distinct cyanide ligands.Key words: NMR, quadrupolar nucleus, chemical shielding tensor, multiple-quantum magic-angle spinning, metal cyanide, spin-spin coupling.

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