Phase Control in Rare Earth Chalcogenide Nanomaterials

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Prof. Sarah Stoll of Georgetown University conducts research to develop new methodologies for synthesizing nanoparticles containing rare earth elements. This is a relatively unexplored class of nanostructures with potentially useful electronic and magnetic properties. The fundamental knowledge to be gained from this research could inform future design of nanoparticle systems for applications in electronics, magnetics, and quantum computing. This project provides to undergraduate and graduate students training in chemical synthesis and the state-of-the-art techniques in characterization of magnetic nanoparticles. In addition to conducting outreach activities at D.C. public schools, Prof. Stoll develops new seminar series for the Georgetown University program called 'Science in the Public Interest' and engages Georgetown students in the organization called the 'National Science Policy Network'. These activities link groups of undergraduate and graduate students interested in science policy making and provide them opportunities to meet representatives from foundations, government and academics who are engaged in science policy.With the support from the Macromolecular, Supramolecular and Nanochemistry Program, the research group of Prof. Stoll develops new solution-phase synthetic methodologies for preparing lanthanide and uranium chalcogenide nanoparticles. This research aims to 1) provide mechanistic insights into the role of precursor reactivity in determining the composition, size, and structure of nanocrystals of these f-block elements; and 2) increase our fundamental understanding of the evolution of energy levels from molecular orbitals to the density of states diagram. Ferromagnetic uranium chalcogenides are of interest because of predicted high surface anisotropy, which should have a significant effect on the hysteresis curves as a function of particle size. In addition, the lanthanide and uranium chalcogenides exhibit strong magneto-optical properties. A suite of techniques (including high resolution transmission electron microscopy, atomic force microscopy, magnetic circular dichroism, X-ray absorption spectroscopy, SQUID magnetometry, solid-state thermolysis, and dynamic light scattering) is employed to characterize the nanoparticles and study their magnetic and electronic properties.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.