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.

Sol-gel synthesis of a nanoparticulate aluminosilicate precursor for homogeneous mullite ceramics

2006 ◽  
Vol 21 (5) ◽  
pp. 1279-1285 ◽  
Author(s):  
Jarkko Leivo ◽  
Mika Lindén ◽  
Cilâine V. Teixeira ◽  
Janne Puputti ◽  
Jessica Rosenholm ◽  
...  
Keyword(s):  
Spinel Phase ◽  
Sol Gel ◽  
Magic Angle Spinning ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bond Density ◽  
Angle Spinning ◽  
Sol Gel Synthesis

An amorphous nanoparticulate aluminosilicate 3/2-mullite precursor has been synthesized and carefully characterized. The sol contained 2-nm particles of Q3(3Al) silica species together with six-coordinated alumina, which suggested an allophane-like structure of the nanoparticles. The sol remained stable for years, and formed an easily redispersible physical gel upon solvent evaporation. The gel crystallized to mullite at temperatures below 1000 °C, without going through any intermediate spinel phase. Thus, the nanoparticulate precursor is regarded as a homogeneous high-purity mullite precursor with a high Si–O–Al bond density, which is useful in the preparation of various nanostructured Al-rich aluminosilicate materials. The sols and gels were characterized by small-angle x-ray scattering, dynamic light scattering, x-ray diffraction, 27Al and 29Si magic-angle spinning (MAS) nuclear magnetic resonance spectroscopy, and differential thermal analysis.

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.

scholarly journals One-step nonhydrolytic sol–gel synthesis of mesoporous TiO2 phosphonate hybrid materials

2019 ◽  
Vol 10 ◽  
pp. 356-362 ◽  
Author(s):  
Yanhui Wang ◽  
P Hubert Mutin ◽  
Johan G Alauzun
Keyword(s):  
Hybrid Materials ◽  
Volume Fraction ◽  
Sol Gel ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
One Step ◽  
Anatase Nanoparticles ◽  
Angle Spinning ◽  
Sol Gel Synthesis

Mesoporous TiO2–octylphosphonate hybrid materials were prepared in one step by a nonhydrolytic sol–gel method involving the reaction of Ti(OiPr)4, acetophenone (2 equiv) and diethyl octylphosphonate (from 0 to 0.2 equiv) at 200 °C for 12 hours, in toluene. The different samples were characterized by 31P magic angle spinning nuclear magnetic resonance, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, and nitrogen physisorption. For P/Ti ratios up to 0.1, the hybrid materials can be described as aggregated, roughly spherical, crystalline anatase nanoparticles grafted by octylphosphonate groups via Ti–O–P bonds. The crystallite size decreases with the P/Ti ratio, leading to an increase of the specific surface area and a decrease of the pore size of the hybrid samples. For a P/Ti ratio of 0.2, the volume fraction of organic octyl groups exceeds 50%. The hybrid material becomes nonporous and can be described as amorphous TiO2 clusters modified by octylphosphonate units, where the octyl chains form an organic continuous matrix.

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.

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.

29Si nuclear-magnetic-resonance and vibrational spectroscopy studies of SiO2–TiO2 powders prepared by the sol-gel process

2001 ◽  
Vol 16 (8) ◽  
pp. 2369-2376 ◽  
Author(s):  
J. P. Rainho ◽  
J. Rocha ◽  
L. D. Carlos ◽  
R. M. Almeida
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Sol Gel ◽  
Magic Angle Spinning ◽  
Treatment Temperature ◽  
Mas Nmr ◽  
Magic Angle ◽  
Titania Content ◽  
Angle Spinning ◽  
Nuclear Magnetic

The sol-gel synthesis and structural characterization of SiO2–TiO2 powders are reported. Samples with titania concentrations in the range of 0 to 30 mol%, calcined at temperatures between 120 and 1300 °C, were characterized by 29Si magic-angle-spinning nuclear-magnetic-resonance (MAS NMR) and cross polarization MAS NMR, Raman and Fourier transform infrared spectroscopies, and powder x-ray diffraction. Tetrahedrally coordinated Ti (IV) ions were found in the titanosilicate matrix. When the titania content increases beyond approximately 10 mol% and upon calcination at temperatures over approximately 700 °C, the segregation of an amorphous silica-rich phase occurs, together with the precipitation of anatase nanocrystallites with average sizes between 3 and 17 nm, depending on the temperature. An increase in the heat treatment temperature, or the titania content, leads to an increase in the degree of homocondensation (Si–O–Si and Ti–O–Ti bonds) and a simultaneous reduction in the degree of heterocondensation (Si–O–Ti bonds).

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.

scholarly journals Chemical and Structural Characterization of Amorphous and Crystalline Alumina Obtained by Alternative Sol–Gel Preparation Routes

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1761
Author(s):  
Izabela Rutkowska ◽  
Jakub Marchewka ◽  
Piotr Jeleń ◽  
Mateusz Odziomek ◽  
Mateusz Korpyś ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Aluminum Oxide ◽  
Physicochemical Properties ◽  
Sol Gel ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Bet Method ◽  
Gel Preparation ◽  
Angle Spinning ◽  
Middle Infrared

Aluminum oxide is one of the most commonly used materials in the industry. It is used in the field of catalysis, refractories, and optics. Despite the fact that there are many techniques available, there is still a great challenge in obtaining a material with desired and designed properties. Nevertheless, there is a great flexibility in making customized alumina materials with desired physicochemical properties synthesized by sol–gel methods. This work consists in characterizing the physicochemical properties of sol–gel synthesized aluminum oxide using different sol–gel preparation routes. Three different sols were obtained by using organic precursors and underwent thermal treatment. The structure (Middle Infrared Spectroscopy, Diffused Reflectance Infrared Spectroscopy, X-ray Diffraction, Magic Angle Spinning Nuclear Magnetic Resonance) and microstructure (Scanning Electron Microscopy with Electron Dispersive Spectroscopy) tests of the materials were carried out. The specific surface area was determined by using the Brunauer–Emmett–Teller (BET) method. Thermal analysis was performed for all the powders, in order to analyze the specific temperature of materials transformation.

Sign in / Sign up

Export Citation Format

Share Document