Ashley Sanchez
Groups STEM Summer Research Program
Major: Intelligent Systems Engineering
Mentor: Baixu Zhu
Superlattices are three-dimensional ordered arrangements of nanoscale units with a fixed geometrical position rather than a randomly distributed position. When superlattices are obtained by nanocrystals, this allows for further understanding of nanocrystals’ unique applications. Typically, the crystallographic orientation of these sphere nanocrystals results in a random generation of superlattices. When these spherical nanocrystals are replaced with non-spherical nanocrystals like polyhedral, unique superlattices could be created and controlled. For this research, we used octahedral nanocrystals rather than sphere nanocrystals. While sphere nanocrystals only follow a transitional order; polyhedral nanocrystals follow both orientational and transitional order which aids us more in our research. Utilizing octahedral nanocrystals, considering both transitional and orientational order, many common nanocrystal superlattice structures have already been obtained. With thorough research and experimental processes, we were able to synthesize oleate-capped manganese oxide nanocrystals and utilize a ligand exchange process to study these self-assembly behaviors of octahedral nanocrystals. By using a Transmission electron microscope (TEM), which can obtain a 3D view of various structures, we can characterize these samples to find the trend behind these complex superlattice structures. Our goal is to explore the effective softness of octahedral nanocrystal assembly behaviors and try to characterize typical crystalline structures based on octahedral nanocrystals. This work is then characterized and graphed in an effective softness graph, which could be used as a simple yet Sanchez 2 strong tool for the future design of nanoparticle superlattices and a precise tool for controlled interparticle distance and packing symmetry. Ultimately leading to a new-found array of crystalline structures. These results could be used for improved control of nanoscale structure, which is critical to the development of sophisticated materials like terahertz, mechanical, Plasmonic, and surface-enhanced Raman spectroscopy substrate technologies.
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