Rare-earth-free white emitting BaTiPO phosphor: revealing its crystal structure and photoluminescence properties

A high intensity bluish-white emitting Ba 2 TiP 2 O 9 phosphor was synthesized by a conventional solid-state reaction method and the precise crystal structure was investigated for the first time by Rietveld refinement analysis. Ba 2 TiP 2 O 9 has a monoclinic crystal structure with a space group C 2/ c (no. 15), which is built out of PO 4 tetrahedra and TiO 5 pyramidal polyhedra connected to form a chain structure along the c -axis. The emission of Ba 2 TiP 2 O 9 is due to a charge transfer transition between Ti 4+ -O 2− in the pyramidal TiO 5 . The obtained Ba 2 TiP 2 O 9 was excited efficiently by UV and VUV and displayed a bright bluish-white luminescence. Crystal structure of a Ba 2 TiP 2 O 9 phosphor has been revealed by Rietveld refinement, it has monoclinic structure which consists of PO 4 tetrahedra and TiO 5 pyramidal polyhedra connected to form a chain structure along the c -axis.