On the structural heterogeneity of supercooled liquids and glasses

The status of our basic understanding of the physics and structure of glasses is presented in the light of recent developments in the experimental, phenomenological, and numerical approach to the description of real systems. Spontaneous and induced dynamic heterogeneities appear in the supercooled state of liquids and become frozen intact below the glass transition point. In most cases, mesoscopic heterogeneities due to partial microphase separation are frozen in glasses. Thus, glasses can be described as dynamically arrested heterogeneous supercooled liquids with more solid-like and liquid-like nanoscale regions. The critical issue is that, depending on material type and temperature, the heterogeneities exhibit different size distributions with the solid-like regions probably displaying a degree of hidden quasi-order. This scenario naturally explains some of the important physical properties of real glasses.