High-entropy oxide (HEO) thermodynamics transcend temperature-centric approaches, spanning a multidimensional landscape where oxygen chemical potential plays a decisive role. Here, we experimentally demonstrate how controlling the oxygen chemical potential coerces multivalent cations into divalent states in rock salt HEOs. We construct a preferred valence phase diagram based on thermodynamic stability and equilibrium analysis, alongside a high throughput enthalpic stability map derived from atomistic calculations leveraging machine learning interatomic potentials. We identify and synthesize seven equimolar single-phase rock salt compositions that accommodate multivalent Mn, Fe, or both, as confirmed by X-ray diffraction and fluorescence. X-ray absorption fine structure spectra reveal predominantly divalent cations. Ultimately, we introduce oxygen chemical potential overlap as a key complementary descriptor predicting HEO stability and synthesizability. Although we focus on rock salt HEOs, our methods are chemically and structurally agnostic, providing a broadly adaptable framework for navigating HEOs thermodynamics and enabling a broader compositional range with contemporary property interest.
@article{arxiv.2503.07865,
title = {Thermodynamics-Inspired High-Entropy Oxide Synthesis},
author = {Saeed S. I. Almishal and Matthew Furst and Yueze Tan and Jacob T. Sivak and Gerald Bejger and Dhiya Srikanth and Joseph Petruska and Christina M. Rost and Susan B. Sinnott and Long-Qing Chen and Jon-Paul Maria},
journal= {arXiv preprint arXiv:2503.07865},
year = {2025}
}