Towards Probabilistic Analysis of Entropy Stabilized Oxides using Density Functional Theory

Entropy Stabilized Oxides (ESOs) [1] are novel materials with many potential applications in modern technology, including in thermoelectric devices and battery cathodes. These materials are enthalpically unfavorable, but entropically favorable due to high configurational disorder, making them a challenge to analyze using enthalpy based methods such as Density Functional Theory (DFT).  To achieve this goal, we have created Python-based software which randomizes the placement of metal cations in a rocksalt lattice, creating an ensemble of microstates for the local environment of an ESO. DFT is used to determine the enthalpy of formation from the single phase metal oxides for each microstate within the ensemble. We then create a statistical-mechanical model based on the DFT computed enthalpies of the microstates by computing the expectation values of relevant energetic, structural, and electronic properties over the entire ensemble of structures. The efficacy of our approach may be tested by direct comparison to experimental characterization such as X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS).

[1] Rost, C. M. et al. Entropy-stabilized oxides. Nat. Commun. 6:8485 doi: 10.1038/ncomms9485 (2015).