Solid State Oxides and Oxyfluorides

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Non-technicalThe rational design of crystal structures based on the chemical nature of molecular components and functionality is a longstanding and exciting research topic in organic solid state chemistry. Only recently has crystal engineering become an emerging area of inorganic solid state chemistry. With the judicious use of the geochemical and environmental science literature, we continue to develop high yield reactions, control purity, and grow single crystals of new materials that lack inversion symmetry. New materials lacking inversion symmetry (or noncentrosymmetric materials) are the basis of all current and future technologies based on piezoelectricity, pyroelectricity and ferroelectricity. Numerous inventions during the past two decades have been created based on noncentrosymmetric structures. All future advances in this area await the education of a new generation of students capable of the design and synthesis of this special combination of atoms which is required to create noncentrosymmetric materials.Technical Abstract DMRThis project aims to understand how to optimize geometries and the electrostatic potential of metal oxo and oxofluoro-species to create order and avoid disorder in the metal-oxygen and metal-fluoride bonds. The crystal symmetries of the oxyfluorides are determined by the network of contacts the surrounding lattice provides, which are in turn deliberately controlled to create chiral, polar, or chiral-polar three-dimensional solids. Noncentrosymmetric structures are those that lack inversion symmetry. Structures lacking inversion symmetry are a requirement for important current and future technologies that have been created by numerous inventions during the past two decades based on piezoelectricity, pyroelectricity, ferroelectricity and second harmonic generation (SHG). These materials provide a large and new class of solids for studies in basic science associated with the noncentrosymmetric space groups. Stable, robust, high-performance nonlinear optical (NLO) materials with enhanced optical properties at the microscopic and macroscopic level depend on inorganic materials which possess a dipole moment and thus exhibit large optical nonlinearities. These materials are essential for the modification of the amplitude, phase, or frequency of an optical signal. Mixed metal oxide fluorides are a new class of high performance inorganic solid state materials that exhibit polar and chiral (sometimes in combination polar and chiral) structures. Students are trained to carry out semi-combinational syntheses and theoretical modeling studies to guide and advance our program of exploratory synthesis and to achieve high quality single crystals. Crystals are essential for structural studies, characterization and physical measurements of materials which exhibit a nonlinear optical response.