The Phase Stability Network of All Inorganic Materials

In the pursuit of unlocking structure-property relationships, a dominant paradigm in materials science has been the bottom-up investigation of how the arrangement of atoms and interatomic bonding in a material determine its macroscopic behavior. Here we consider a complementary approach, a top-down study of the organizational structure of networks of materials, based on the interaction between materials themselves. We unravel the "phase stability network of all inorganic materials" as a dense complex network of 21,000 thermodynamically stable compounds (nodes) connected with 41 million tie-lines (edges) defining their two-phase equilibria as computed by high-throughput density functional theory. The connectivity of nodes in the materials network shows a lognormal distribution, while the network itself shows small-world behavior, with a number of compounds acting as "hubs" having connections to nearly all other compounds. Analyzing the structure and topology of the materials network has the potential to uncover new knowledge inaccessible from the traditional atoms-to-materials approaches. We use the connectedness of materials in the network to derive a general, data-driven metric for reactivity, the "nobility index", and quantitatively identify the noblest materials in nature.