Impact of magnesium on the structure of aluminoborosilicate glasses: A solid‐state NMR and Raman spectroscopy study

Abstract

Seven magnesium-containing aluminoborosilicate glasses, with three to five oxides, have been studied through comprehensive multi-nuclear solid-state NMR ( 11 B, 27 Al, 29 Si, 23 Na, 17 O and 25 Mg) and Raman spectroscopy. The progressive addition of cations and the substitution of sodium and calcium by magnesium illuminate the impact of magnesium on the glass structure. The proportion of tri-coordinated boron drastically increased with magnesium addition, demonstrating the poor chargecompensating capabilities of magnesium in tetrahedral boron units. Oxygen-17 NMR showed the formation of mixing sites containing both Na and Mg near non-bridging oxygen sites. Furthermore, a high magnesium content appears to result in the formation of two sub-networks (boron and silicon rich) with different polymerisation degrees as well as to promote the formation of high-coordination aluminium sites (Al[V] and Al [VI]). Finally, magnesium coordination ranging from four to six, with a mean value shifting from five to six along the series, suggests that magnesium might endorse an intermediate role in these glasses.

Structure and disorder in MgSiO3 glasses above megabar pressures via nuclear magnetic resonance: DFT calculations

“…Identifying local Mg environments in silicate glasses offers critical knowledge on densification in primordial Mg‐rich mantle melts and chemical durability of Mg‐bearing oxide glasses. However, 25 Mg—an NMR active nuclide of Mg with low gyromagnetic ratio ( γ )—exhibits low sensitivity, 94–96 and thus, the investigation of 25 Mg NMR of MgSiO 3 glass under compression has been challenging 97–99 . Systematic relationships among the Mg coordination number, Mg–O bond distance [ d (Mg–O)], and NMR parameters in Mg‐bearing oxide glasses have remained lacking.…”

“…However, 25 Mg-an NMR active nuclide of Mg with low gyromagnetic ratio (γ)exhibits low sensitivity, [94][95][96] and thus, the investigation of 25 Mg NMR of MgSiO 3 glass under compression has been challenging. [97][98][99] Systematic relationships among the Mg coordination number, Mg-O bond distance [d(Mg-O)], and NMR parameters in Mg-bearing oxide glasses have remained lacking. Here, our simulation results reveal the first detailed pressure-induced evolution of Mg coordination environments ( [4,5,6,7,8] Mg) under compression in the 25 Mg δ cs versus C q plot (Figure 5).…”

Influence of Magnesium on the Structure of Complex Multicomponent Silicates: Insights from Molecular Simulations and Neutron Scattering Experiments

“…In our previous study, we characterized experimentally using multinuclear NMR analysis and Raman spectroscopy seven silicate glasses, which are divided as follows: four magnesium-containing aluminoborosilicate glasses (N19M8, N13M13, N8M19, and N0M12), a complementary calcium-containing glass (N19C8), a sodium aluminoborosilicate glass (N26M0), and a simple reference silicate glass (A0B0). Glass names and compositions are given in Table , wherein N and M represent the nominal rounded concentration (mol %) of Na 2 O and MgO, respectively.…”

“…25 Mg solid-state nuclear magnetic resonance (NMR) has also been performed over the years, but only a few results on crystalline or simple glasses are found in the literature, − with recent results only on borosilicate glasses, as discussed in our previous study, rendering the precise evaluation of the magnesium local environment difficult. Indeed, increasing glass complexity causes higher difficulty in understanding the interactions between magnesium and the other cations, as it varies with the chemical composition. , …”

“…The present study follows an in-depth experimental structural characterization of seven glasses (with three to five oxides) of the form SiO 2 –B 2 O 3 –Al 2 O 3 –Na 2 O–(MgO, CaO) for the most complex ones, five of which containing magnesium, with the addition of a calcium counterpart to one of the glasses . The whole series was simulated by classical MD using the Wang et al potential .…”