Chemical Pathways for Controlling Polymorphism in Nanoscale Metal Chalcogenides

这项由固体与材料化学(SSMC)项目颁发的奖项支持宾夕法尼亚州立大学Raymond Schaak教授的工作，该工作旨在识别和了解导致过渡金属硫化物和硒的纳米颗粒非平衡相形成的化学因素，包括硫化锌、硒锌以及钴、镍和锰的几种硫化物和硒化物。目标材料表现出各种有趣和有用的电、磁和光学性质，而它们的晶体结构直接影响它们的性质。这项研究建立在利用化学路线合成非平衡相的新兴能力的基础上，这些化学路线从可溶的前体中形成溶液中的纳米颗粒固体。这样的发现通常是偶然的，涉及大量变量和复杂的原位化学。在这个项目中，Schaak教授的团队研究了这些新固体形成的反应途径，揭示了重要的见解，有助于根据基本化学原理建立一个选择性地针对所需非平衡相的预测框架。扩展固体采用的晶体结构在定义其性质方面起着关键作用。同时，用于合成固体的技术和条件有助于影响其形成的晶体结构。该项目旨在识别和了解在一个可能有多个结构可访问的系统中选择性地导致形成一种晶体结构而不是其他晶体结构的化学因素。这些见解将帮助研究人员更可预测地合成具有目标性质的所需材料。该项目为不同的研究生和本科生群体提供多学科培训。重点是通过专门设计的本科生研究项目，将本科生研究人员团队直接纳入项目的技术目标。

This award by the Solid State and Materials Chemistry (SSMC) program supports work by Professor Raymond Schaak at the Pennsylvania State University to identify and understand the chemical factors that lead to the formation of nanoparticulate non-equilibrium phases of transition metal sulfides and selenides, including ZnS, ZnSe, and several sulfides and selenides of Co, Ni, and Mn. The targeted materials exhibit a variety of interesting and useful electronic, magnetic, and optical properties, and their crystal structures directly impact their properties. This research builds on emerging capabilities for synthesizing non-equilibrium phases using chemical routes that form nanoparticulate solids in solution from soluble precursors. Such discoveries are usually serendipitous, involving a large number of variables and complex in-situ chemistry. In this project, Prof. Schaak's group investigates the reaction pathways by which these new solids form to reveal important insights that can help lead to a predictive framework for selectively targeting desired non-equilibrium phases based on fundamental chemical principles.The crystal structure that an extended solid adopts plays a key role in defining its properties. At the same time, the techniques and conditions used to synthesize a solid can help to influence the crystal structure that it forms. This project seeks to identify and understand the chemical factors that selectively lead to the formation of one crystal structure instead of others in a system where multiple structures may be accessible. These insights will help researchers to more predictably synthesize desired materials with targeted properties. This project provides multi-disciplinary training to a diverse group of graduate and undergraduate students. Emphasis is placed on integrating teams of undergraduate researchers directly into the technical goals of the project through specially designed undergraduate research projects.