The Determinants of Crystalline Phase in Bottom-Up Nanocrystal Synthesis

在化学系大分子、超分子和纳米化学项目的支持下，来自范德比尔特大学的Janet Macdonald教授旨在帮助阐明纳米晶体是如何形成的，并提供对其结构和隐藏性质的见解。所有固体的性质都是由组成它们的元素及其排列方式决定的。即使是两种元素的简单组合，比如硫化铁，也能产生多达九种不同的晶体结构，它们的化学和磁性、导电性、颜色、其他性质和潜在用途都大不相同。这种复杂性使得晶体科学非常有趣。从该研究项目中获得的知识有望帮助发现生产纯形式的单个纳米晶体类型的条件。专注于纳米晶体无机材料的研究可能最终释放出潜在的颠覆性技术，因为这种尺寸的晶体通常在太阳能电池、电池、医学磁成像、半导体和新型催化剂方面具有巨大的应用潜力。该项目的一项推广活动是利用在铁化学方面获得的知识，重新发现久违的制备Anishinaabe古代岩石艺术的方法。此外，该项目将为研究生和本科生提供严格的研究训练，以帮助建立未来的科学劳动力。根据该奖项，Macdonald教授和她的团队将对相位控制合成进行广泛、全面和系统的研究。锰、铁、钴、镍和铜的硫族化合物（硫化物、硒化物和碲化物）特别要检查，因为它们具有特别复杂的相图。利用有机硫族化合物文库来分离前驱体的动力学速率和分解机理在相测定中的作用。将绘制阶段景观图，这将为目标综合变更提供指导，以实现一个阶段优于另一个阶段。第二个目标是解决关于纳米晶体合成中如何控制多型的长期争论。从分子配位化学中收集的工具将被用于实现更广泛地跨元素周期表的多晶相控制，以瞄准已经预测但从未见过的“鬼相”。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。

With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Janet Macdonald, from Vanderbilt University aims to help elucidate how nanocrystals form, as well as provide insight into their structure and hidden properties. The properties of all solids are determined by the elements that comprise them and their arrangement. Even a simple combination of two elements, like iron sulfide, can produce as many as nine different crystal formations with vastly different chemical and magnetic behavior, conductivity, color, other properties, and potential uses. This complexity makes crystalline science incredibly intriguing. The knowledge to be gained from this research project is expected to help in the discovery of conditions to produce individual nanocrystal types in pure form. Focusing research on nanocrystalline inorganic materials could ultimately unleash potentially disruptive technologies as this size of crystal generally has a great potential for applications in solar cells, batteries, medical magnetic imaging, semiconductors, and novel catalysts. One outreach activity of the project, involves using the knowledge gained on iron chemistry to rediscover long-lost methods for preparing ancient rock art of the Anishinaabe. In addition, this project will provide a rigorous research training for graduate and undergraduate students to help build the future workforce in science.Under this award, Professor Macdonald and her team will perform a wide, sweeping, and systematic study of the phase-controlled synthesis. Manganese, iron, cobalt, nickel, and copper chalcogenides (sulfides, selenides and tellurides) be examined in particular because they have particularly complex phase diagrams. Libraries of organochalcogenides will be employed to separate the role of the kinetic rate from the decomposition mechanism of the precursors in phase determination. Maps will be drawn of the phase landscape that will provide guidance for targeted synthetic changes to achieve one phase over another. The second aim strives to resolve a long-standing debate about how polytypes are controlled in nanocrystal synthesis. Tools gleaned from molecular coordination chemistry will be employed with the goal of achieving polymorphic phase control more broadly across the periodic table to target "ghost phases" that have been predicted but never seen.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.