A unified 23 Na NMR chemical shift correlation with structural parameters in multicomponent silicate‐based glasses

From a large ensemble of 34 silicate‐based glasses from the borosilicate, phosphosilicate, and borophosphosilicate systems that comprise either Na as a sole glass‐network modifier or when mixed with Ca, we established a good correlation between the 23 Na average isotropic chemical shift ( δ ¯ iso ) and the average coordination number of Na and the mean Na–O distance. The latter parameters were obtained by atomistic molecular dynamics simulations. We also demonstrated thatδ ¯ iso is essentially independent on the precise network forming (Si, B, P) species but depends primarily on the net molar fraction of Na and Ca, thereby offering a straightforward 23 Na chemical shift prediction from the glass composition alone.