Synthesis of Complex and Advanced Chalcogenide Materials

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PART 1: NON-TECHNICAL SUMMARYThe continued advancement of society on many levels relies on the steady use of new materials that can enable new functions or solve long-standing problems and challenges. Solid state materials underpin many products and processes on which our modern society depends. This project deals with the broader question: How do we discover and synthesize new solid state materials? It develops the fundamental science and principles of synthesis and how they can be used as tool to design and synthesize useful new materials. Specifically, the project, supported by the Solid State and Materials Chemistry program within the Division of Materials Research, focuses on developing the chemistry of metal chalcogenides. Chalcogenides are compounds of sulfur, selenium and tellurium and they are important in a broad variety of scientific investigations and technologies. The project pursues chalcogenide materials discovery as a science coupled with the study of crystal structure, physical properties including ion-exchange, charge transport and photo-response of the new materials. The primary goals are to learn how reactions leading to solid state chalcogenides can be controlled so known materials can be avoided and new materials can be accessed. This research activity enhances, as well as challenges, our scientific understanding. It will also enhance the effectiveness of existing technological applications and impact new applications. Possible technological impact could be via new semiconductors, materials with high Li mobility, quantum materials and ion-exchange sorbent materials for environmental remediation. The project provides diverse opportunities for graduate and undergraduate students, including those from underrepresented groups, to learn critical thinking skills that will help advance future scientific research. Additionally, the educational program encompasses outreach to high schools on ion exchange materials and dissemination of YouTube videos on safe use of the advanced synthetic methods used in the project. PART 2: TECHNICAL SUMMARYThis project pursues chalcogenide materials discovery as a science coupled with the study of crystal structure, physical properties including ion-exchange, charge transport and photo-response of the new materials. Within an overarching theme of contributing to fundamental understanding of synthesis, particularly using flux-based methods, the project studies: (a) the understanding the synthesis of complex Li-containing chalcogenide phases; (b) the formation of stable boron clusters as building blocks in chalcogenides; (c) the understanding of the synthesis routes that lead to subchalcogenides with low-valent metals; (d) the rational design of ion-exchangers. The expected benefits are: i) broad new insights regarding the reactivity and stability of lithium-containing chalcogenide phases; ii), expansion of the small class of the little-known boron cluster-based chalcogenides; iii) new chemistry and bonding in subchalcogenides and their impact on physical and chemical properties, and iv) delineation of the factors involved in the selective binding of heavy soft metal ions by metal sulfides ion-exchangers and use of this knowledge to create novel compositions using ion-exchange chemistry. Possible technological impact of these materials could be new semiconductors for radiation detection, materials with high Li mobility, topological quantum materials, open framework systems, and ion-exchange sorbent materials for environmental remediation. This project is supported by the Solid State and Materials Chemistry program within the Division of Materials Research.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.