Optimal thermodynamic conditions to minimize kinetic byproducts in aqueous materials synthesis

Abstract

Thermodynamics has strong predictive power for materials synthesis by identifying the stability region of target phases, but does not give explicit information about the relative competitiveness of undesired byproduct phases in synthesis. In this work, we propose a quantitative and computable measure to guide the selection of synthesis conditions. Defining thermodynamic competition as the difference in driving force between a target phase and its competing phases, we hypothesize that phase-pure synthesis becomes more likely when this thermodynamic competition is minimized. We systematically validate this hypothesis with two approaches: (1) we analyze large-scale solution synthesis procedures as text-mined from the literature, and show that experimentally-optimized synthesis conditions are near the predicted thermodynamic optimum point, and (2) direct experimental evaluation of synthesis in LiIn(IO3)4 and LiFePO4, which show that phase-pure synthesis occurs only when thermodynamic competition is minimized. Our work demonstrates that a quantitative assessment of thermodynamic competition is an effective descriptor for synthesis optimization and a promising tool for optimizing aqueous solution-based experimental synthesis conditions.

Thermodynamic Stability and Anion Ordering of Perovskite Oxynitrides

“…However, these diagrams are often constructed by solving the Nernst equation to draw phase boundaries between competing phases, an approach that cannot consider the free energy or concentration of each species individually. In contrast, our computational Pourbaix diagrams are derived using a grand thermodynamic potential for each species, which enables us to consider the energy contributions of both ion concentration and chemical potential for all elements. , To the best of our knowledge, this work represents the first time this method has been applied to quaternary oxynitride systems.…”

“…In contrast, our computational Pourbaix diagrams are derived using a grand thermodynamic potential for each species, which enables us to consider the energy contributions of both ion concentration and chemical potential for all elements. 28,54 To the best of our knowledge, this work represents the first time this method has been applied to quaternary oxynitride systems.…”