Supercooled Liquids and Polyamorphism

We have discovered a solid, apparently amorphous phase of triphenyl phosphite to which the supercooled liquid converts, a phase distinct from both the glass and the crystal. To date, this is the clearest and best identified case of a first-order transition from a liquid to another apparently amorphous condensed phase. We discuss this phenomenon in terms of a recently formulated theory of supercooled liquids that predicts and naturally incorporates the existence of such low-temperature phases, thereby suggesting that its existence is a general phenomenon intimately connected with the existence and properties of supercooled liquids. In accord with the theory, we also suggest that although the X-ray scans do not indicate any lattice structure, these apparently amorphous phases may in fact be defect-ordered structures with large unit cells.