Collaborative Research: New Phase Diagrams for Predictive Solvothermal Synthesis in Non-Aqueous Solvents

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

Non-Technical Summary Solvothermal synthesis involves precipitating a solid out of a supersaturated solution and is a common materials synthesis route for functional materials. Many classes of important materials cannot be easily precipitated using water as the solvent; including intermetallics, sulfides, and nitrides; which are more readily synthesized in non-aqueous organic solvents. The number of available organic solvents is large, but there is currently no rigorous understanding of which combination of solvent and starting material is best to synthesize a given target material. With this project, supported by the Solid State and Materials Chemistry Program in NSF’s Division of Materials Research, Professor Wenhao Sun at the University of Michigan and Professor Daniel Shoemaker at the University of Illinois Urbana-Champaign build new predictive theoretical models to better understand which compounds precipitate out of supersaturated non-aqueous solutions. This scientific understanding allows chemists to skip the tedious trial-and-error efforts of solution synthesis optimization and enables the rational design of synthesis recipes for the manufacture and processing of new, more complex, or higher-quality materials that drive technological innovation. The research is carried out by undergraduate and graduate students, who are trained in computational materials science and experimental thermochemistry during this project. Technical Summary Many classes of materials are synthesized in organic solvents, such as ethanol, ethylene-glycol, ammonia, acetonitrile, hydrazine, DMSO, DMF, THF, etc. Currently, there are no thermodynamic frameworks to guide solvothermal synthesis in non-aqueous media, meaning chemists largely rely on heuristics for precursor solubility and laborious trial-and-error efforts for solution synthesis optimization. This project undertakes a combined computational and experimental research program to develop the first thermodynamic phase diagrams to guide solvothermal synthesis in non-aqueous organic solvents. The project involves measuring and developing predictive models for the chemical potentials of solvated species in non-aqueous solvents, and then combining these ion chemical potentials with high-dimensional thermodynamic frameworks to predict the solubility and chemical equilibria of complex materials under various non-aqueous solvents and conditions. These new solvothermal phase diagrams offer a rigorous foundation to rationally design recipes for the targeted solution-based synthesis of advanced solid-state materials. Broad availability for the tools developed in this project is aided by interfacing with freely-available and widely-used thermochemical databases. Hands-on learning is supported by precisely aligning model precipitation reactions with undergraduate thermodynamics lessons in chemistry and materials science. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.