Optical Materials in Na-Y-Si-O and Related Quaternary Systems

This project utilizes the materials genome approach in order to discover new compounds at an accelerate rate. Novel materials for optical applications, such as luminescent scintillators, are desired for improvement of properties. Using aqueous speciation and density functional theory (DFT) calculations for experimental guidance, potential new scintillating materials may be discovered in the efforts to improve scintillation materials capabilities. Synthesis work targets existing compounds of already-high density, then examines metal substitutions for potential discovery of new compounds with higher density. Na-O-Si-Y and Y-Zr-O systems were investigated with the two existing compounds, NaY9Si6O26 and Y4Zr3O12, to investigate if these could be synthesized under mild hydrothermal conditions. Metal salts were mixed with complexing agents, base and water, then enclosed in a hydrothermal vessel at 200 °C for a few to several days. After reaction and isolation by wash/centrifuge, products were analyzed by powder X-ray diffraction (XRD), and scanning electron microscopy with energy-dispersive X-ray analysis (SEM/EDS). For Y4Zr3O12, XRD and SEM revealed primarily Y2O3 with prismatic and hexagonal crystals, and for NaY9Si6O26, EDS revealed a quaternary phase of approximate composition Na5Y4Si12O31, with spheroidal crystalline formations. Future work will include further investigation of this quaternary product, as well as continued feasibility and substitution studies using hydrothermal methods