Navigating and Predicting Oxide Synthesis Recipes in High-Dimensional Thermodynamic Space

There are a wide diversity of synthesis control parameters that can be manipulated for the targeted synthesis of a desired functional oxides. Unfortunately, optimizing these synthesis parameters can be a laborious, trial-and-error process—which is rapidly becoming the critical bottleneck in the experimental realization of computationally-designed materials. Here, I will illustrate how state-of-the-art <i>ab initio </i>thermodynamic calculations can be coupled with direct <i>in situ</i> experimental observation to guide and predict rational synthesis routes to complex oxide materials. First, I will demonstrate the critical role of interfacial reactions in the non-equilibrium phase evolution of Na_xCoO₂¹and YBa₂Cu₃O₇² during solid-state synthesis, and discuss strategies to selectively control the thermodynamic landscape to preference kinetically facile phase transformation pathways. In this high-dimensional thermodynamic space, the optimization of oxide synthesis procedures would be greatly facilitated by an infrastructure for higher-dimensional phase diagrams. I will next present a generalization of Gibbs’ Phase Rule, which provides a theoretical pathway to construct and deploy high (≥3) dimensional phase diagrams that include axes beyond <i>T</i>, <i>P</i> and <i>N</i>; including surface, elastic, electromagnetic and electrochemical work. These new classes of phase diagrams will offer unprecedented insight for the rational synthesis control of functional oxide materials.<br/>¹Nature Materials,<b> 19</b>, 1088 (2020)<br/>² Advanced Materials 33, 24 (2021)<br/>³Arxiv: 2105.01337 (2021)