A self-activated silicate phosphor of Na5YZrSi6O18

A new self-activated silicate phosphor of Na5YZrSi6O18 was prepared by a solid-state reaction method. The phase formation was confirmed by X-ray powder diffraction measurement. The photoluminescence excitation and emission spectra, X-ray-excited luminescence, decay curves, quantum efficiencies and the color coordinates were investigated. It can be efficiently excited by UV light and X-ray and presents unusual green emission (centered at 475 nm) from Zr4+ to O2− charge transfer transition. Meanwhile, the phosphor shows long-lasting phosphorescence with duration time above 3 h after the removal of excitation. The afterglow curves and thermo-luminescence were measured for pure and rare earth ions (RE = Yb, Er, Ho, Dy, Tb, Sm, Nd) doped Na5YZrSi6O18. The possible defects and the mechanism of long-lasting phosphorescence were suggested on the base of the strong disorder of the multiply cation sites in the lattices.