A NMR-Driven Reverse Monte Carlo Study of Sodium Borate Glasses

Thibault Charpentier (1) , Erwan Chesneau (1) , Laurent Cormier (2) , Gregory Tricot (3)

1 LSDRM - Laboratoire Structure et Dynamique par Résonance Magnétique (LCF)
2 IMPMC_PALM - Propriétés des amorphes, liquides et minéraux [IMPMC]
3 LASIRE - Laboratoire Avancé de Spectroscopie pour les Intéractions la Réactivité et l'Environnement - UMR 8516

Borate glasses are known to have a large fraction of the boron atoms involved in superstructural units like boroxol or pentaborate rings, in addition to the double coordination of boron atoms (3 and 4). This generates the boron's anomaly, which is a non-linear evolution of properties upon the addition of sodium oxide. In this work, we investigate theoretically and experimentally the structure of sodium borate glasses using B and Na NMR, classical and ab-initio molecular dynamics (MD) simulations and neutron diffraction. We observe that only aiMD produces structural models with a non-negligible fraction of super-structural units (6 membered rings) but still below the one determined by two-dimensional B MQMAS NMR. In order to improve our structural models, in particular to include a larger fraction of superstructural units, we develop a hybrid reverse monte carlo (HRMC) scheme combining MD with NMR and neutron data, taking the fraction of superstructural units as an adjustable parameter.

Mots clés: Reverse Monte Carlo; NMR; Molecular Dynamics; DFT-NMR computations

Domaines: Matériaux

Thibault Charpentier, Erwan Chesneau, Laurent Cormier, Gregory Tricot. A NMR-Driven Reverse Monte Carlo Study of Sodium Borate Glasses. Glass and Optical Materials Division Annual Meeting (GOMD 2022), May 2022, Baltimore, United States. ⟨cea-03681018⟩