Amorphous–amorphous transformations under pressure are generally explained by changes in the local structure from low- to higher-fold coordinated polyhedra^1,2,3,4. However, as the notion of scale invariance at the critical thresholds has not been addressed, it is still unclear whether these transformations behave similarly to true phase transitions in related crystals and liquids. Here we report ab initio-based calculations of compressed silica (SiO₂) glasses, showing that the structural changes from low- to high-density amorphous structures occur through a sequence of percolation transitions. When the pressure is increased to 82 GPa, a series of long-range (‘infinite’) percolating clusters composed of corner- or edge-shared tetrahedra, pentahedra and eventually octahedra emerge at critical pressures and replace the previous ‘phase’ of lower-fold coordinated polyhedra and lower connectivity. This mechanism provides a natural explanation for the well-known mechanical anomaly around 3 GPa, as well as the structural irreversibility beyond 10 GPa, among other features. Some of the amorphous structures that have been discovered mimic those of coesite IV and V crystals reported recently^5,6, highlighting the major role of SiO₅ pentahedron-based polyamorphs in the densification process of vitreous silica. Our results demonstrate that percolation theory provides a robust framework to understand the nature and pathway of amorphous–amorphous transformations and open a new avenue to predict unravelled amorphous solid states and related liquid phases^7,8.

压力下的无定形-无定形转变通常可以通过局部结构从低倍配位多面体到高倍配位多面体^1,2,3,4的变化来解释。然而，由于临界阈值处的尺度不变性的概念尚未得到解决，因此尚不清楚这些转变是否与相关晶体和液体中的真实相变相似。在这里，我们报告了基于从头计算的压缩二氧化硅 (SiO ₂) 玻璃，表明从低密度到高密度无定形结构的结构变化是通过一系列渗流转变发生的。当压力增加到 82 GPa 时，在临界压力下会出现一系列由角或边共享的四面体、五面体和最终八面体组成的长程（“无限”）渗透团簇，并取代之前的“相”低-折叠协调多面体和较低的连通性。这种机制为众所周知的 3 GPa 附近的机械异常以及超过 10 GPa 的结构不可逆性等特征提供了自然的解释。已发现的一些无定形结构与最近报道的柯石英 IV 和 V 晶体相似^5,6，突出了 SiO _{5的主要作用}石英玻璃致密化过程中基于五面体的多晶型物。我们的结果表明，渗流理论提供了一个强大的框架来理解无定形-无定形转变的性质和途径，并开辟了一条新的途径来预测解开的无定形固态和相关液相^7,8。