Predicting and accessing metastable phases

Metastable forms of matter are invaluable to our everyday lives, from advancing technology to understanding biological processes, with their unique properties often offering novel functionality. Despite their importance, synthesizing metastable phases is more art than science, often either serendipitous or trial-and-error. Insight into the amount of stored energy needed to form a metastable phase can aid in their fabrication. Here, we calculate metastable phase diagrams, from which we extract the metastability threshold - the excess energy stored in the metastable phase relative to the ground state. Using lanthanide sesquioxides (Ln(2)O(3)) as a case study, we demonstrate how metastable phase diagrams provide new insight into their synthesis and irradiation behavior. We successfully predict the sequence of metastable phases induced by irradiation in Lu2O3, forming three metastable phases with increasing irradiation fluence.