Public Release: 13-Feb-2018
Breaking local symmetry: Why water freezes but silica forms a glass
Tokyo - Everyone knows that water freezes at 0°C. Life on Earth would be vastly different if this were not so. However, many are less familiar with water's cousin, silica, whose wayward behavior when cooled has long puzzled scientists.
Unlike water, silica (SiO2) does not freeze easily. When liquid silica cools, its atoms fail to arrange into an ordered crystal. Instead, as temperature decreases, the liquid state survives even far below the nominal freezing temperature; this phenomenon is termed supercooling. Eventually, the atoms are simply locked into place wherever they are, preserving the structural disorder of the liquid. The resulting frozen state of matter - mechanically solid, but microscopically liquid-like - is a glass.
https://www.eurekalert.org/pub_releases/2018-02/iois-bls021318.php
