Since they were first reported almost two decades ago, fragile-to-strong (FTS) transitions have been observed in all categories of glass-forming systems including metallic, covalent, ionic and molecular liquids. In these systems, a transition from Arrhenius to non-Arrhenius viscosity behavior is observed in conjunction with anomalies in multiple thermodynamic variables including the heat capacity, the thermal expansion coefficient and the isothermal compressibility. A review of experimental evidences supporting the existence of FTS transitions is presented. In particular FTS transitions are found to be concomitant with a peak in heat-capacity as well as density extrema associated with a negative expansion coefficient in the region of the transition. Moreover, spectroscopic analyses also show distinct structural changes across these liquid-liquid transitions. Reports of FTS transitions in each category of liquid are reviewed.

自从大约二十年前首次报道它们以来，在所有类型的玻璃形成系统中都观察到了脆性到强（FTS）转变，包括金属，共价，离子和分子液体。在这些系统中，结合多个热力学变量（包括热容量，热膨胀系数和等温可压缩性）的异常，观察到了从Arrhenius到非Arrhenius粘度行为的转变。提供了支持FTS过渡的实验证据的综述。特别地，发现FTS过渡与热容量的峰值以及在过渡区域中与负膨胀系数相关的密度极值同时发生。此外，光谱分析还显示出在这些液-液过渡过程中明显的结构变化。审查了每种液体类别的FTS过渡报告。