Rare-earth-free white emitting Ba2TiP2O9 phosphor: revealing its crystal structure and photoluminescence properties

Abstract

A high intensity bluish-white emitting Ba₂TiP₂O₉ 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. Ba₂TiP₂O₉ has a monoclinic crystal structure with a space group C2/c (no. 15), which is built out of PO₄ tetrahedra and TiO₅ pyramidal polyhedra connected to form a chain structure along the c-axis. The emission of Ba₂TiP₂O₉ is due to a charge transfer transition between Ti⁴⁺–O²⁻ in the pyramidal TiO₅. The obtained Ba₂TiP₂O₉ was excited efficiently by UV and VUV and displayed a bright bluish-white luminescence.