ABSTRACT. Materials exhibiting noncentrosymmetric (NCS) crystal structures lack inver- sion symmetry. They are important for current and future technologies based on piezoelectricity, non-linear optics and chiral separation. NCS materials are critical to stimulating efficient and high- yield asymmetric catalysis of fossil resources (petroleum, coal, and natural) into consumable fuels for transportation, industrial production and electricity generation. Despite their industrial func- tionality, efforts to design and discover new NCS materials remains challenging, due in part, to the limited control over the fundamental anion "building blocks" coordinating cations with chemistries susceptible to NCS displacements. To overcome these materials disparities, we propose a new ap- proach for designing noncentrosymmetric (NCS) crystal structures in elpasolite-structured vana- date oxyfluorides (E-OXF) by using a strategy based on ab initio crystal engineering of the ligand framework. The goal of this research is to build a reliable set of crystal-chemistry guidelines that dictate the optimal geometries and chemistries favorable to NCS structures and harness that knowl- edge to efficiently design E-OXF. The objective is to investigate the role electrostatic interactions, geometric packing and bond covalency have on promoting NCS structures through changes in the local VOxF6−x polyhedra and extended polyhedral tiling geometries. We propose to accomplish this computationally by isolating each atomic structure–fundamental chemical interaction through density functional theory (DFT) techniques coupled with group theoretical phenomenological mod- els. These investigations will allow us to identify the microscopic origins of the acentric distortions by disentangling competing and/or cooperative structure–interaction effects, enabling the rational design and subsequent experimental synthesis of NCS E-OXF.
|Effective start/end date||9/1/14 → 8/31/15|
- American Chemical Society Petroleum Research Fund (PRF # 52138 - DNI10)