Solid-State Oxides and Oxide-Flourides

Intellectual Merit: Emerging technologies require high-performance nonlinear optical (NLO) materials that exhibit enhanced optical properties at the microscopic and macroscopic level. The rational design of crystal structures, in particular noncentrosymmetric (NCS) materials, and how to target polar, polar¡Vchiral, and chiral structures, is an ongoing theme in crystal engineering. A new class of potentially high performance NLO inorganic materials, solid-state oxide-fluorides, has been identified with the synthesis of new compounds containing [MOxF6-x]2- units in inorganic, solid-state environments. In the process it has been discovered that i) the use of fluoride ligands with early-transition metals (ETMs) enhances the second-order Jahn-Teller distortion in comparison to pure oxide ETM compounds, ii) the synthesis of NCS materials can be achieved with the use of polar basic-building units (BBUs), iii) design of NCS BBUs can predictably lead to NCS structures, iv) the synthesis of compounds that contain two, separate anionic BBUs is likely to result in an NCS compound, and v) the synthesis of vanadium oxide ¡V fluoride compounds can produce energy-storage materials such as high-potential primary batteries. Drawing from these learned principles, a program of discovery-based research on NCS structures based on acentric ETM oxide- fluorides (ETMOFs) is planned. These materials comprise a large and new class of solids with properties associated with piezoelectricity, pyroelectricity, ferroelectricity and second harmonic generation (SHG). The structural-property relationships that give rise to high, low, or null nonlinearities of the NLO material are examined l. Finally, the growth of large crystals (on the order of 1 cm3) allows detailed analysis with measurements of the NLO tensor (ƒÓƒw and phase-matchability properties, and other properties of interest such as piezoelectricity. Broader Impacts: The materials synthesized will have potential use in relaxor ferroelectrics and non-linear optics. These compounds will have a high damage threshold and the potential for bulk growth to create large, single crystals suitable for optical use and examination. Such analyses of basic principles of the chemistry by graduate students and postdoctoral associates ¡V who are engaged in local education, teaching, mentoring , and leader ship ¡V will facilitate broad understanding of stable solid-state compounds. Non-technical summary