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

溶剂热合成涉及从过饱和溶液中沉淀固体，是功能材料的常用材料合成路线。许多种类的重要材料不容易用水作为溶剂沉淀；包括金属间化合物、硫化物和氮化物；它们更容易在非水有机溶剂中合成。可用的有机溶剂的数量很多，但目前还没有严格的了解哪种溶剂和起始材料的组合是最好的合成给定的目标材料。在美国国家科学基金会材料研究部固态与材料化学项目的支持下，密歇根大学的孙文浩教授和伊利诺伊大学厄巴纳-香槟分校的Daniel Shoemaker教授建立了新的预测理论模型，以更好地了解哪些化合物从过饱和非水溶液中沉淀出来。这种科学的理解使化学家能够跳过冗长乏味的溶液合成优化的试错工作，并能够合理设计合成配方，用于制造和加工新的、更复杂的或更高质量的材料，从而推动技术创新。该研究由本科生和研究生进行，他们在该项目中接受了计算材料科学和实验热化学方面的培训。许多种类的材料是在有机溶剂中合成的，如乙醇、乙二醇、氨、乙腈、肼、二甲基亚砜、二甲基亚砜、四氢呋喃等。目前，还没有热力学框架来指导非水介质中的溶剂热合成，这意味着化学家在很大程度上依赖于前体溶解度的启发式方法和费力的试错努力来优化溶液合成。本项目采用计算和实验相结合的研究方案，开发第一个热力学相图，以指导非水有机溶剂的溶剂热合成。该项目包括测量和开发非水溶剂中溶剂化物质化学势的预测模型，然后将这些离子化学势与高维热力学框架相结合，预测复杂材料在各种非水溶剂和条件下的溶解度和化学平衡。这些新的溶剂热相图为合理设计基于溶液的先进固态材料合成配方提供了严格的基础。本项目开发的工具的广泛可用性得益于与免费提供和广泛使用的热化学数据库的接口。动手学习是由精确对准模型沉淀反应与本科热力学课程在化学和材料科学的支持。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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 SummaryMany 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.