Theoretical Predictions of MB5N5: Atom-Stuffed Boronitride Clathrate Cages Derived from the High-Pressure Superhydride

Abstract: This study investigates 198 MX5Y5 (X, Y = B, C, or N) clathrate-like structures derived from MH10 superhydrides using high-throughput Density Functional Theory (DFT) geometry optimizations and phonon calculations. A wide variety of electropositive and electronegative encapsulated atoms were considered. From all of the studied systems only 34 MB5N5 phases were found to be dynamically stable at ambient pressure. The highest 1-atmosphere superconducting critical transition temperature was predicted for FB5N5. However, ab initio molecular dynamics simulations revealed that all of the identified superconducting phases decompose by 300~K at 1~atm, while only eleven semiconducting phases remained thermally stable. Our findings underscore the critical role of kinetic and thermal stability in predicting viable superconductors. The electronic structure of the MB5N5 compounds were rationalized in terms of electron donating and withdrawing intercalants, and machine-learning based predictions of their mechanical properties were compared with those of an empty boronitride cage.