Figure 3: Structural changes in the liquid and volume measurements.

(a) Examples of total structure factor S(Q) on cooling from about 1,300 K to ~610 K. (*) marks the glassy state. The structure factors are vertically shifted for clarity. See Supplementary Fig. S1 for more structure factors. (b) Temperature dependence of 1/Q₁³ (ų) on cooling (blue diamonds and squares) and heating (red dots). Filled yellow triangles are isothermal measurements on stepwise heating. The arrow points out a clear discontinuity of 1/Q₁³ upon cooling at around 830 K. The lower and upper lines are the data fittings with Yavari’s equation (see text) for two liquid states. (c) The FWHM of the 1st peak of S(Q) (see inset) versus temperature during thermal cycles. The arrows point out the clear slope changes in the temperature range 760–830 K during cooling and 1,100–1,200 K upon reheating. The dashed line is the assumed heating data trace if crystallization can be avoided on reheating. (d) Macroscopic liquid volume measured in the ESL during cooling and reheating. The deviation of the macroscopic volume (density) data on reheating (arrow) from the data on cooling is due to the process of partial crystallization and re-melting at around 800–1,100 K, which is the temperature range where the XRD data for the liquid state are not available on reheating, seen as a data gap between the solid circles in b and c.