CAREER: Unveiling the structure and stability of prenucleation clusters and their roles in crystallization pathway and final crystal structure

一个多世纪以来，科学家们一直在研究成核作用，因为它极大地影响了我们生活的方方面面，例如通过药物生产和处理尿结石来实现公共健康，以及影响化肥和食品等行业。尽管有很长的研究历史，但由于在亚纳米尺度上描述微小和随机现象的困难，理解成核的机制和对晶体结构的影响仍然是具有挑战性的。这个职业奖由NSF材料研究部的固体和材料化学计划和既定的刺激竞争研究计划(EPSCoR)联合资助，旨在弄清楚盐溶液的结构如何随着浓度的增加而变化，以及这种结构如何影响最终的晶体形成。为了克服这些挑战，将与阿贡国家实验室和橡树岭国家实验室合作，将悬浮技术与强大的X射线和中子散射相结合。这项研究的结果将大大加强我们对复杂的结晶过程及其对最终晶体结构的影响的理解。这一知识可能会使制药、化肥和电池等行业受益。在整个项目中，将形成一个联盟作为一个教育平台，以促进STEM领域的多样性，教育年轻的科学家和工程师，并通过爱荷华州立大学领导的现有推广计划与爱荷华州的K-12学生、教师和家长分享我们的发现。技术和核作用主导随后的结晶、晶体生长以及最终晶体的结构和性能。最近，有报道称成核分多个步骤进行，形成预成核团簇(PNC)。显然，PNC在多步成核和最终的晶体结构中起着至关重要的作用，但人们对它们的性质知之甚少。提出这项研究的理由是，从机理上理解复杂结晶可能会为开发控制所需晶相的形核和生长的方法提供新的机会。为此，该职业奖由美国国家科学基金会材料研究部的固态和材料化学项目和既定的促进竞争研究计划(EPSCoR)共同资助，旨在确定PNC在水盐溶液中随浓度变化的结构演变，以及溶液结构对结晶路径和最终晶体结构的影响。目前的实验障碍将通过将溶液静电悬浮器(SEL)与Argonne国家实验室的同步辐射X射线散射和橡树岭国家实验室的中子散射相结合来克服。该项目的长期目标是开发一个预测框架，以预测和控制不同水溶液中的多路径和多步骤结晶，以获得最终晶体产品中所需的微观结构。这项拟议的研究将导致在阐明电解液溶液中复杂结晶的机制及其对最终晶体结构的影响方面取得纵向进展。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARYFor over a century, scientists have been studying nucleation because it greatly affects various aspects of our lives, such as public health through drug production and dealing with urinary stones, as well as impacting industries like fertilizers and foods. Despite the long history of research, understanding the mechanism and influence of nucleation on crystal structures is still challenging due to the difficulty in characterizing tiny and random phenomena at the sub-nanoscale level. This CAREER award, jointly funded by the Solid State and Materials Chemistry program in NSF’s Division of Materials Research and the Established Program to Stimulate Competitive Research (EPSCoR), aims to figure out how the structure of salt solutions changes as their concentration increases and how this structure affects the final crystal formation. To overcome the challenges, a levitation technique and powerful X-ray and neutron scattering will be combined, collaborating with Argonne National Laboratory and Oak Ridge National Laboratory. The outcomes of this study will significantly enhance our understanding of the complex process of crystallization and its impact on the final crystal structure. This knowledge could benefit industries like pharmaceuticals, fertilizers, and batteries. Throughout the project, a consortium will be formed as an educational platform to promote diversity in the STEM field, educate young scientists and engineers, and share our findings with K-12 students, teachers, and parents in Iowa through existing outreach programs led by Iowa State University.TECHNICAL SUMMARYNucleation dominates the subsequent crystallization, crystal growth, and the structure and properties of final crystals. Recently, nucleation has been reported to occur in multiple steps, forming pre-nucleation clusters (PNCs). It is apparent that PNCs play a critically important role in multi-step nucleation and the final crystal structure, yet their nature is poorly understood. The rationale for the proposed research is that a mechanistic understanding of complex crystallization will likely provide new opportunities to develop a method to control the nucleation and growth of desired crystal phases. For this reason, this CAREER award, jointly funded by the Solid State and Materials Chemistry program in NSF’s Division of Materials Research and the Established Program to Stimulate Competitive Research (EPSCoR), aims to identify the concentration-dependent structural evolution of PNCs in aqueous salt solutions and the influence of solution structure on the crystallization pathways and the final crystal structure. The current experimental obstacles will be overcome by integrating the solution electrostatic levitator (SEL) with synchrotron X-ray scattering at Argonne National Laboratory and neutron scattering at Oak Ridge National Laboratory. The long-term goal of the project is to develop a predictive framework to anticipate and control the multi-pathway and multi-step crystallization in various aqueous solutions to obtain desired microstructures in the final crystal products. The proposed research will lead to a vertical-step advancement toward elucidating the mechanism of complex crystallization in electrolyte solutions and its influence on the final crystal structure.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.