Polarizable force-fields were developed for modelling aluminosilicate glasses including aspherical shape of the ions. Comparison of the computed 17O MQMAS NMR spectra shows unprecedented agreement with experimental data, both in spectra (left) and in the T-O-T’ population variation with the compositions (right).
DFT computation of NMR parameters with specific methods for solids, i.e., with periodic boundary conditions, have now become essential in solid-state NMR studies.[1,2] We are developing integrated methodologies based on the combination of molecular dynamics simulations with NMR to help the detailed interpretation of experimental data for glasses. We applied them to aluminosilicate glasses to improve our understanding of the local structural features controlling the NMR parameters of nuclei like 27Al, 29Si, 23Na, 43Ca[4-6] or rare-earth elements such as Y+++ and Sc+++. We have shown the importance of polarization effects in the design of force fields (fitted to DFT) for significantly improving the mixing between network formers (Al/Si) as unambiguously determined by oxygen-17 NMR. Polarizable force-fields has been developed for simple ternary SiO2-B2O3-Na2O borosilicate glasses and currently extended to more complex glass compositions.
• Systèmes complexes et transition énergétique › Systèmes désordonnés et matériaux / Disordered systems, materials
• Institut Rayonnement Matière de Saclay
• La RMN à l 'IRAMIS • Spectrocopie nucléaires : RMN (Résonance Magnétique Nucléaire) - Spectroscopie Mössbauer