Poisson's ratio and the fragility of glass-forming liquids

Abstract

The nature of the transformation by which a supercooled liquid ‘freezes’ to a glass—the glass transition—is a central issue in condensed matter physics^1,2,3 but also affects many other fields, including biology⁴. Substantial progress has been made in understanding this phenomenon over the past two decades, yet many key questions remain. In particular, the factors that control the temperature-dependent relaxation and viscous properties of the liquid phase as the glass transition is approached (that is, whether the glass-forming liquid is ‘fragile’ or ‘strong’^5,6,7) remain unclear. Here we show that the fragility of a glass-forming liquid is intimately linked to a very basic property of the corresponding glass phase: the relative strength of shear and bulk moduli, or Poisson's ratio.