While it is broadly known that solid compounds may exist in distinct crystalline arrangements (polymorphs), the notion that some liquids may also adopt distinct phases with dissimilar structures and densities is much less widespread. One of the reasons is that these liquid‐liquid (L‐L) transitions often occur in the supercooled equilibrium regime below the melting line and can be challenging to observe experimentally. Glass‐forming liquids that supercool over significant temperature ranges can therefore constitute useful systems for investigating these transitions. In this paper we review experimental evidence for L‐L transitions in chalcogenide systems. In that respect, L‐L transitions are found to be associated with transitions from fragile to strong viscous behavior in these glass‐forming liquids. Moreover, they are signaled by extrema in multiple thermodynamic functions and sharp change in physical properties such as electrical conductivity. Finally, while the physical principles underlying these transitions are still unclear, they have been shown to play a critical role in the function of PCMs that are poised to transform fast computing technologies.

中文翻译：

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玻璃成型系统中的液相转变及其对存储技术的影响

虽然众所周知，固体化合物可能以不同的晶体排列（多晶型物）存在，但某些液体也可能采用结构和密度不同的不同相的观念还不那么广泛。原因之一是这些液-液（L-L）转变通常发生在熔融线以下的过冷平衡状态下，可能难以通过实验观察。因此，在显着温度范围内过冷的玻璃成形液体可以构成研究这些转变的有用系统。在本文中，我们回顾了硫族化物系统中L–L跃迁的实验证据。在这方面，发现在这些玻璃成型液体中，L–L转变与从易碎行为转变为强粘性行为有关。此外，它们通过多种热力学功能的极值和物理性质（例如电导率）的急剧变化发出信号。最后，尽管这些转换的物理原理尚不清楚，但已证明它们在准备转换快速计算技术的PCM功能中起着关键作用。