Fig. 2: Linear correlation between MRD and SiO₂ mol% and inverse correlation between fragility index (m) and MRD.

In (a), 27 neutron-measured glasses with the same values of NBO/T ratio (defined and listed in Supplementary Note 1 and Table 2) are plotted with the same color. Glasses with similar SiO₂ mol% values but different NBO/T ratios are shown as clustered symbols with different colors, manifesting their similar MRD. The linear equation is derived by least-squares fitting of the data for all glasses. The errors of both MRD ( ± 0.01 Å) and SiO₂ mol% (±0.1) values are smaller than the symbol size. In (b), MRD values of 48 CAS glasses are calculated by the linear equation obtained in (a). The glasses in each categorized group are plotted with the same color symbols, with their references noted in the legend. The linear equation is derived by least-squares fitting of the data for all the glasses. Only 10 glass-forming liquids (eutectic and non-eutectic glasses shown in blue and green triangles) from ref. [25] have their fragility-index errors reported; the fragility-index errors for four glasses measured in this study (red open circles) are from linear fittings, and two of those were measured twice with independent sample preparations. The error of calculated MRD values is 0.03 Å. ^a: ref. [22], ^b: ref. [21], ^c: ref. [25], ^d: ref. [24], ^e: ref. [23].