Novel bluish white -emitting $CdBaP_2O_7: Eu^{2+} $phosphors for near-UV white-emitting diodes

A new bluish white-emitting phosphor based on a phosphate host matrix, CdBaP$_2$O$_7$:Eu$^{2+}$, was prepared by a conventional solid-state reaction method. The photoluminescence properties were investigated in both ultraviolet (UV) and vacuum ultraviolet (VUV) regions. The band-gaps of Eu-doped CdBaP$_2$O$_7$ powders can be tuned in the ranges of 2.26–2 eV. The Eu$^{2+}$-doped CdBaP$_2$O$_7$ phosphor was efficiently excited at wavelengths of 250–400 nm, which is suitable for the blue emission band for near-UV light-emitting-diode (LED) chips (360–400 nm) and red emission peaks up to 700 nm. CdBaP$_2$O$_7$:Eu$^{2+}$ displays two different luminescence centers, which were suggested to Ba$^{2+}$ and Cd$^{2+}$ sites in the host. The dependence of luminescence intensity on temperatures was measured. The chromaticity coordinates and activation energy for thermal quenching were reported. The phosphor shows a good thermal stability on temperature quenching