Photoluminescence, thermal stability and structural properties of red-emitting phosphors Na5YSi4O12:Eu3+

A series of Na5YSi4O12:xEu(3+) (x = 0-100 mol%) red-emitting phosphors were prepared by the solid-state method. The powder X-Ray diffraction (XRD) measurement was introduced and the crystal structure of the phosphors was crystallized in the trigonal system with the space group of R-3c (167). The concentration dependent photoluminescent excitation spectra (PLE), emission spectra (PL) as well as luminescence decay curves were recorded and the optimum doping concentration of Eu3+ ions was evaluated. The synthesized phosphors can be efficiently excited by ultraviolet (UV) to blue light and emit bright red-emitting. Under the excitation of 266 nm wavelength, several emission bands can be observed, ascribing to the transitions from excited state of D-5(0) to the ground states of F-7(0-4). It is somewhat unexpected that the PL emission from the D-5(0) -> F-7(0) transition is remarkable, which is principally believed to be forbidden. The intensity and decay lifetime of the emission were measured to vary strongly with temperature, indicating that the as-synthesized silicates with excellent photoluminescence properties could be promised for multifunctional applications. In addition, the luminescence mechanism was briefly discussed.