Ab Initio Structure Determination and Photoluminescent Properties of an Efficient, Thermally Stable Blue Phosphor, Ba2Y5B5O17:Ce3+

The crystal structure of a novel barium yttrium borate, Ba2Y5B5O17, was determined using a combination of ab initio global optimization algorithms and density functional theory calculations along with Rietveld refinement of high resolution synchrotron X-ray powder diffraction data. Synthesized using a high-temperature solid-state route, the structure consists of edge- and corner-sharing Y- and Ba-centered polyhedra along with BO3 trigonal planes. Ba and Y occupy four crystallographically independent sites with two fully occupied by Y and two having a statistical mixture of Y and Ba. Substituting Ce3+ into the structure for Y3+ yields blue photoluminescence (lambda(em) = 443 nm) upon excitation with UV (lambda(em) = 365 nm) light. The emission of this new compound is efficient with an external quantum yield of 70% and is stable as a function of temperature with a quenching temperature of approximate to 400 K