Predictive screening of phase stability in high-entropy ceramics

Abstract

High-entropy materials offer unprecedented opportunities for tailoring mechanical, chemical, and thermal properties for enhanced performance across a multitude of applications, including energy storage, catalysis, and nuclear reactors. However, a major challenge in advancing their discovery lies in accurately predicting their single-phase stability and formation ability. Theoretically, phase stability can be predicted from free energies. In practice, this approach has been often unreliable for high-entropy materials because of limitations in the available experimental data needed to fit free energy terms. Ab initio calculations have been used to predict phase stability, but mostly by identifying descriptors that may correlate with stability. Here, we demonstrate that the phase stability of high-entropy ceramics can be accurately predicted by directly calculating free energy terms using ab initio calculations. The proposed approach is computationally efficient and physics-based and agrees with currently available experimental data. In the case of a composition where predictions of our models appeared inconsistent with the literature, we synthesized the sample experimentally and confirmed the accuracy of our models. We have also identified several new single-phase compositions of high-entropy ceramics that have not been previously reported. Our approach provides a new pathway for accelerating the design of high-entropy ceramics without the need for descriptors.