Energy transfer and multicolor tunable emission in single-phase Tb3+, Eu3+ co-doped Sr3La(PO4)3 phosphors

A series of green-to-red color-tunable Sr3La(PO4)3:Tb3+, Eu3+ phosphors were prepared by high temperature solid-state method. The crystal structures, photoluminescence properties, fluorescence lifetimes, and energy transfer of Sr3La(PO4)3:Tb3+, Eu3+ were systematically investigated in detail. The obtained phosphors show both a green emission from Tb3+ and a red emission from Eu3+ with considerable intensity under ultraviolet (UV) excitation (~377 nm). The emission colors of the phosphors can be tuned from green (0.304, 0.589) through yellow (0.401, 0.505) and eventually to red (0.557, 0.392) due to efficient Tb3+-Eu3+ energy transfer (ET). The Tb3+→Eu3+ energy transfer process was demonstrated to be quadrupole-quadrupole mechanism by Inokuti-Hirayama model, with maximum ET efficiency of 86.3%. The results indicate that the Sr3La(PO4)3:Tb3+, Eu3+ phosphors might find potential applications in the field of lighting and displays.