Figure 4: Comparison of heat capacity maxima between the liquid Vit.1 and other glass formers.

Solid and open symbols represent experimental and simulation data, respectively (the last data point of SiO₂ is extracted¹³ from Fig. 3 of Scheidler et al.⁵²). The heat capacity values are plotted against the T_g-scaled temperature. For both SiO₂ and BeF₂, the heat capacity maxima with the dynamic crossover are located beyond the normal measurement range, far above T_m, suggesting that the liquid–liquid transitions are in the stable liquid state at the high temperature. In the case of water, the suggested liquid–liquid transition is in the supercooled liquid regime where the c_p peak is observed in the water confined by nanopores to avoid crystallization. The liquid–liquid transition of Vit.1 upon heating is above T_m and has a sharper c_p peak than that of SiO₂ and BeF₂. These liquid–liquid transitions are considered as off-critical phenomena, comparing with the critical phenomenon of the lambda transition in the non-liquid superlattice Fe₅₀Co₅₀ with a very sharp lambda c_p peak. Inset: the heat capacity of argon^13,54 appears in various forms around its liquid–gas critical point at different pressures. (Parts of the figure are reproduced from Wei et al.¹³).