A5048988054- Advanced NMR Techniques and Applications
- Glass properties and applications
- Solid-state spectroscopy and crystallography
- X-ray Diffraction in Crystallography
- Advanced Condensed Matter Physics
- NMR spectroscopy and applications
- Nuclear materials and radiation effects
- Crystallization and Solubility Studies
- Advanced ceramic materials synthesis
- Inorganic Fluorides and Related Compounds
- High-pressure geophysics and materials
- Advanced Battery Materials and Technologies
- Material Dynamics and Properties
- Luminescence Properties of Advanced Materials
- Zeolite Catalysis and Synthesis
- Mineralogy and Gemology Studies
- Nuclear Physics and Applications
- Geological and Geochemical Analysis
- Crystal Structures and Properties
- Advancements in Battery Materials
- Clay minerals and soil interactions
- Ferroelectric and Piezoelectric Materials
- Atomic and Subatomic Physics Research
- Catalytic Processes in Materials Science
- Metal-Organic Frameworks: Synthesis and Applications
Conditions Extrêmes et Matériaux Haute Température et Irradiation
2016-2025
Université d'Orléans
2016-2025
Centre National de la Recherche Scientifique
2016-2025
ETH Zurich
2025
Centre de Gestion Scientifique
2023
The Ohio State University
1995-2020
Laboratoire de Mathématiques d'Orsay
2017
University of Puerto Rico at Carolina
2017
Université d'Artois
2014
École Nationale Supérieure de Chimie de Montpellier
2008-2009
Abstract Early transitional metal carbides are promising catalysts for hydrogenation of CO 2 . Here, a two-dimensional (2D) multilayered 2D-Mo C material is prepared from Mo T x the MXene family. Surface termination groups (O, OH, and F) reductively de-functionalized in (500 °C, pure H ) avoiding formation 3D carbide structure. studies show that activity product selectivity (CO, CH 4 , –C 5 alkanes, methanol, dimethyl ether) controlled by surface coverage tunable pretreatment conditions....
Abstract Herein, a robust microporous aluminum tetracarboxylate framework, MIL‐120(Al)‐AP, (MIL, AP: Institute Lavoisier and Ambient Pressure synthesis, respectively) is reported, which exhibits high CO 2 uptake (1.9 mmol g −1 at 0.1 bar, 298 K). In situ Synchrotron X‐ray diffraction measurements together with Monte Carlo simulations reveal that this structure offers favorable capture configuration the pores being decorated density of µ ‐OH groups accessible aromatic rings. Meanwhile, based...
The structure and properties of glasses melts in the MgO-Al2O3-SiO2 (MAS) CaO-MgOAl2O3- SiO2 (CMAS) systems play an important role Earth material sciences. Aluminum has a crucial influence these systems, its environment is still questioned. In this paper, we present new results using Raman spectroscopy 27Al nuclear magnetic resonance on MAS CMAS glasses. We propose Al/Si tetrahedral distribution glass network different Qn species for silicon essentially Q4 VAl aluminum. For glasses, increase...
High-field 17O MAS NMR was used to investigate the binding of self-assembled monolayers 17O-enriched phosphonic acids deposited on a titania anatase support. The spectra were recorded at two different magnetic fields (9.4 and 17.6 T), improve reliability simulations resonances. T offer an excellent resolution between oxygen sites, P═O, P−O−H, P−O−Ti, thus greatly facilitating their quantification. data reported here give direct evidence extensive formation Ti−O−P bonds in surface...
The nature of γ-alumina (γ-Al2O3) surface sites leaves many open questions today, and solid-state NMR spectroscopy has been proposed used as a tool for assessing their structure. Here, we calculated 27Al parameters from first principles in periodic boundary conditions large number Al with different coordination, potentially present on the alumina surface. accordingly these change level hydroxylation thereby pretreatment temperature γ-Al2O3. While chemical shift is little affected by...
Abstract Understanding the links between chemical composition, nano-structure and dynamic properties of silicate melts glasses is fundamental to both Earth Materials Sciences. Central this whether distribution mobile metallic ions random or not. In systems, such as window glass, it well-established that short-range structure not but metal cluster, forming percolation channels through a partly broken network corner-sharing SiO 4 tetrahedra. alumino-silicate melts, extensively used in industry...
The development of thermally driven water-sorption-based technologies relies on high-performing water vapor adsorbents. Here, polymorphism in Al-metal-organic frameworks is disclosed as a new strategy to tune the hydrophilicity MOFs. This involves formation MOFs built from chains either trans- or cis- µ-OH-connected corner-sharing AlO
The two-dimensional $^{17}\mathrm{O}$ dynamic-angle spinning solid-state nuclear magnetic resonance spectrum of silica glass produced from the melt was measured. From this a three-dimensional histogram correlating chemical shift, quadrupolar coupling constant, and asymmetry parameter for bridging oxygen obtained. Using existing correlations between NMR parameters local structure, distribution in mapped into histograms...
Fluoroaluminate molten salts are used in the Hall-Heroult industrial process for production of aluminum by electrolysis. To better understand mechanism dissolution alumina (Al2O3) cryolitic melts, we have studied structure these liquids up to 1025 °C in-situ NMR 27Al, 23Na, 19F, and 17O, using a laser-heated experimental setup. From experiments can propose quantification different aluminum-bearing species AlF4-, AlF52-, AlF63- liquid give direct evidence existence at least two oxy-fluoride...
We have investigated by 27Al nuclear magnetic resonance spectroscopy some compositions in the Ln2O3−Al2O3−SiO2 (Ln = Y or La) ternary phase diagram containing more than 60 mol % of SiO2. One- and two-dimensional high-field (17.6 T) high-speed (30 kHz) magic angle spinning experiments been performed along with simulations spectra to quantify amount penta-coordinated aluminum present those glasses as a function composition. Very high-temperature allowed follow selected samples from 2200 °C...
We have investigated the Al/Si ordering in pseudoisolated pairs of tetrahedral sites structure crystalline gehlenite Ca2Al2SiO7 by means 29Si and 27Al NMR first-principles quantum mechanical calculations. spectra isotopically enriched samples enables precise determination population two silicon Si–(OAl)3-n(OSi)n (n = 0, 1) hence amount Al–O–Al linkages. This leads to a reliable model-free quantification departure from Loewenstein rule an experimental enthalpy 50.4 ± 1.6 kJ/mol fully...
The only easy way to prepare amorphous alumina is via thin film deposition. For this reason, the disorder in has not yet been fully investigated. We have used very high-field (20 T) solid state 27Al NMR spectroscopy analyze structural modifications of films with deposition temperature (Td). were deposited by metalorganic chemical vapor Td range 360–720 °C. Depending on Td, composition either AlO1+x(OH)1–2x (0 ≤ x 0.5) or Al2O3. From 1D magic angle spinning (MAS) and 2D multiple-quantum...
Abstract Y 3 Al 5 O 12 (YAG) is a widely used phosphor host. Its optical properties are controlled by chemical substitution at its YO 8 or AlO 6 /AlO 4 sublattices, with emission wavelengths defined rare‐earth and transition‐metal dopants that have been explored extensively. Nonstoichiometric compositions 3+x 5‐x ( x ≠ 0) may offer route to new distributing over two more sublattices simultaneously, producing local coordination environments for the activator ions. However, YAG typically...
We have investigated the structure of five disilicate glass compositionsK2O·2SiO2, (Na0.25K0.75 )2O·2SiO2, (Na0.50K0.50 (Na0.75K0.25)2O·2SiO2, and Na2O·2SiO2using 2D 17O Dynamic Angle Spinning (DAS) Nuclear Magnetic Resonance (NMR). The nonbridging bridging oxygen sites can be resolved in isotropic DAS spectrum. resonance shifts from 16.1 ppm K2O·2SiO2 to 11.8 Na2O·2SiO2 remains almost identical width. line shapes mixed compositions are broader with a maximum intensity that continuously...
The determination of the nature and structure surface sites after chemical modification large area oxides such as silica is a key point for many applications challenging from spectroscopic view. This has been, instance, long-standing problem reacted with alkylaluminum compounds, system typically studied model supported methylaluminoxane aluminum cocatalyst. While (27)Al solid-state NMR spectroscopy would be method choice, it been difficult to apply this technique because quadrupolar...
We have investigated the 29Si−O−29Si 2J scalar spin−spin coupling constant in two crystalline polymorphs and a glass of 29Si isotopically enriched wollastonite CaSiO3 composition. In samples, line widths less than 1 Hz are observed indirect dimension simple J-resolved NMR experiment leading to 2JSiOSi values 1.5, 3.6, 8.0 determined with high accuracy ±0.1 Hz. The very resolution obtained those compositions enabled us evidence strong effects two-dimensional spectra. particular, additional...
Unlike the long-range order of ideal crystalline structures, local is an intrinsic characteristic real materials and often serves as key to tuning their properties final applications. Although researchers can easily assess ordering using two-dimensional imaging techniques with resolution that approaches atomic level, diagnosis, description, qualification in three dimensions much more challenging. Solid-state nuclear magnetic resonance (NMR) its panel continually developing instruments...