Structural study of lanthanum aluminoborate glasses combining molecular dy.namics, nuclear magnetic resonance and neutron diffraction

93 rd Annual Meeting of the German Society of Glass Technology (GTV) in conjunction with the Annual Meeting of French Union for Science and Glass Technology (USTV)International audienceln this work, we investigate the structure and properties of (1-x)LaB306-xAh03 glasses (x:S:O.375) using sond state NMR and neutron diffraction combined with molecular dynamics simulations. This study aims at understanding the mechanism of aluminium oxide incorporation in lanthanum metaborate glass (LaB 3 0 6) [1] and its impact on structural features. 11 B and 27AI NMR experiments have been performed to obtain the atomic speciation of boron (B0 3 and B0 4) and aluminium (AI0 4 • 5 • 6). Two samples were enriched with oxygen-17 to obtain the BO, NBO population and advanced 2D through-bond heteronuclear correlation (170 _11 B, 170 _ 27 AI) was performed to highlights the distribution of NBO on the BOx and AIO x structural units, whereas 11 B_27 AI 2D NMR revealed their connectivity. However, concerning superstructural units, more precise information are difficult to extract because of broad NMR shift distribution due to the amorphous structure of the glass. We therefore perform Molecular Dynamics (MD) simulations. As shown in previous studies , classical MD (based on empirical potential) cannot reproduce superstructural units in contrast to ab-initio MD (aiMD). Nevertheless, aiMD is an expensive computational time method and is therefore limited in the quenching rate 50 that too much liquid like structures are generated. In order to overcome the se limitations, a Hybrid Reverse Monte Carlo modelling approach has been developed accounting for ail constraints provided by NMR, in addition to the neutron and X-ray structure factors to converge into stable structures answering to ail experimental data