Solid State Chemistry of Crystalline and Glassy Chalcogenides

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This project deals with the effectiveness of salt fluxes to lead to new materials in the broad chalcogenide class of compounds. The ability to control chemical reaction systems and to discover new materials through developing general synthetic methodologies defines one of the main challenges to our understanding of the relationships between chemistry, crystal structures, and properties in complex solids. The project focuses on complex metal chalcophosphate and chalcoarsenate materials. This class continues to present marvelous scientific challenges and it is broadly relevant to many technological applications. We anticipate new materials with interesting and potentially useful physical properties such as semiconducting behavior, second harmonic generation, glass formation, and reversible phase-change crystal to glass transitions. The project explores (a) lithium polythiophosphate fluxes (b) alkali metal polythioarsenate and polyselenoarsenate fluxes (c) 31P NMR spectroscopy to investigate poly-thiophosphate fluxes and reactions performed in such fluxes. (d) Finally, we will investigate and study the properties of glass forming systems occurring in certain element combinations. The project will educate and expose students in a worthwhile intellectual discourse. The students working on the project will receive outstanding training in solid-state chemistry and materials research. They will acquire a direct awareness of the relevance of their materials to science and technology. The proposed activity will strive to furnish a meaningful, coherent research and education program for students so that they, as future independent scientists, are able to generate, handle and manipulate novel classes of solid-state materials. Relatively few laboratories in the US provide the type of training proposed. Undergraduate students also participate in this type of research, which has a lasting impact on their college laboratory experience and future career choices. %%%New materials are at the core of many advanced technologies and products. This project seeks to discover new materials using novel synthesis techniques and to train students in the discourse of this type of research. The materials belong to the broader class of semiconductors and are expected to possess interesting and potentially useful physical properties. These include controllable electrical conductivity, photoactivity, glass forming properties and phase-change properties. This project will investigate new phase-change materials relevant to non-volatile data storage and computer memory applications. The methodology developed and the insights gained relevant to the formation, chemistry and properties of unusual solids, could enable or facilitate useful technologies and thus could make an important contribution to science and could have a significant impact in a number of technologies and by extension on the US economy. Graduate and undergraduate students participating in this type of will have a wide range of future career choices, and will be very competitive in the job market. The results of this research will be available to the public. The broad dissemination of scientific results and knowledge through the communications media, the web and journal publications will help enhance the public's scientific understanding and appreciation.