Solid-State Oxides and Oxide-Fluorides

The use of oxide and fluoride ligands with early-transition metals (ETMs) enhances second-order Jahn-Teller distortions in comparison to pure oxide ETM compounds. A program of discovery-based research on noncentrosymmetric (NCS) structures based on acentric ETM oxide- fluorides (ETMOFs) is planned. Targeted synthesis of NCS materials by hydrothermal, solvothermal, and solid-state methods will be achieved through the use of polar, anionic basic-building units (BBUs). Measurements of nonlinear optical (NLO) properties such as second harmonic generation (SHG) and piezoelectricity will be performed on large (on the order of cm3) single crystals of discovered materials grown by the floating zone method. Experimental structural and phase transition analysis of NCS materials by single crystal and powder x-ray and neutron diffraction will be used together with theoretical analysis by methods including Bond Valence Sum (BVS) theory, Density Functional Theory (DFT), and Molecular Dynamics (MD) simulations. The proposed research, including detailed examinations of NCS structures and the dynamic forces at work during phase-transitions in these materials, will lead to discovery of new NCS materials and new strategies for future NCS materials synthesis.