Color-tunable phosphor of Sr3YNa(PO4)3F:Tb3+via interionic cross-relaxation energy transfer

A series of color-tunable Sr3YNa(PO4)(3)F:Tb3+ phosphors with a fluorapatite structure were synthesized by a traditional high-temperature solid state reaction. The emitting color tuning from blue to green can be observed by gradually increasing Tb3+ concentrations, which is attributed to the enhanced cross-relaxation (CR) between Tb3+ ions, as described by (D-5(3), F-7(6))-(D-5(4), F-7(0)). The CR process is analyzed based on the Dexter and Inokuti-Hirayama model, which is assigned to the electric dipole-dipole interaction. The energy transfer critical distance between Tb3+ ions is evaluated to be 18.1 angstrom. In addition, the thermal quenching mechanism of Sr3YNa(PO4)(3)F:Tb3+ is also investigated. At the general working temperature of an LED (423 K), the luminescence intensity still maintains 81% and 92% with the Tb3+ concentration of 10 and 30 mol%, respectively, indicating an excellent thermal quenching performance of Tb3+. Due to the good optical and thermal properties, the Sr3YNa(PO4)(3)F:Tb3+ phosphor can be used as a promising green emitting phosphor candidate in the field of white light applications.