What is it about?
Magnesium is a crucial component in a broad swathe of amorphous aluminosilicate materials that range from commercial display glass to magmas. The structural role that it plays is, however, largely unknown because of (i) the chameleon-like nature of the magnesium coordination environment; (ii) the limitations in x-ray scattering experiments that originate from the low atomic number of magnesium; and (iii) the difficulty in interpreting the results from 25Mg solid-state NMR experiments. Here, we address this issue by combining diffraction and solid-state NMR techniques.
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Why is it important?
We find a hitherto unknown increase in the Mg-O coordination number and bond distance as the structural role of magnesium changes from a network-modifier to a charge-compensator. We show that 25Mg NMR is not currently an accurate probe of the glass structure because of the broad distribution of electric field gradients associated with the different sites of the Mg2+ ions that originates from structural disorder.
Perspectives
It was a pleasure to work with experts in different techniques to uncover the structural role played by magnesium in these model glassy materials. The route to the results was not straighforward. We had to re-measure the coherent neutron scattering length of the 25Mg iosotope.
Professor Philip S Salmon
University of Bath
Read the Original
This page is a summary of: Structure of diopside, enstatite, and magnesium aluminosilicate glasses: A joint approach using neutron and x-ray diffraction and solid-state NMR, The Journal of Chemical Physics, December 2022, American Institute of Physics,
DOI: 10.1063/5.0125879.
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